Displaying publications 1 - 20 of 121 in total

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  1. Direct production of polyhydroxybutyrate from waste starch by newly-isolated Bacillus aryabhattai T34-N4
    Bomrungnok W, Arai T, Yoshihashi T, Sudesh K, Hatta T, Kosugi A
    Environ Technol, 2020 Nov;41(25):3318-3328.
    PMID: 30987543 DOI: 10.1080/09593330.2019.1608314
    Polyhydroxybutyrate (PHB) is a natural microbial polyester produced by a variety of bacteria and archaea from renewable resources. PHB resembles some petrochemical plastics but is completely biodegradable. It is desirable to identify suitable microbial strains and develop processes that can directly use starch from agricultural wastes without commercial amylase treatment. Here, PHB production using starch from agricultural waste was developed using a newly isolated strain, Bacillus aryabhattai T34-N4. This strain hydrolyzed cassava pulp and oil palm trunk starch and accumulated up to 17 wt% PHB of the cell dry weight. The α-amylase of this strain, AmyA, showed high activity in the presence of cassava pulp starch (69.72 U) and oil palm trunk starch (70.53 U). High expression of amyA was recorded in the presence of cassava pulp starch, whereas low expression was detected in the presence of glucose. These data suggest that starch saccharification by amyA allows strain T34-N4 to grow and directly produce PHB from waste starch materials such as cassava pulp and oil palm trunk starch, which may be used as low-cost substrates.
    Matched MeSH terms: alpha-Amylases
  2. Microwave-assisted extraction of polysaccharides from Micromelum minutum leaves using citric acid monohydrate-glycerol based deep eutectic solvents and evaluation of biological activities
    Md Yusoff MH, Shafie MH
    Anal Chim Acta, 2024 Dec 01;1331:343351.
    PMID: 39532430 DOI: 10.1016/j.aca.2024.343351
    BACKGROUND: The extraction of polysaccharides using an acidic extraction media has been extensively reported, highlighting its effectiveness in yielding high-quality polysaccharides. A higher concentration of acidic solution could hydrolyze the structure of polysaccharide, while a low concentration reduces the extraction efficiency. Despite this challenges, deep eutectic solvents (DES) were introduced as an alternative extraction medium due to additional interactions such as inter and intra-molecular interactions, Van de Waals, hydrogen bond, and electrostatic interactions, which could improve the polysaccharide extraction efficiency and biological activities. Furthermore, the extraction conditions such as extraction medium and extraction parameters could affect the properties of polysaccharides as well as influence their structure-activity relationship for biological activities.

    RESULTS: The result showed that the microwave-assisted extraction of Micromelum minutum leaf polysaccharide (MMLP) using DES as an extraction media (MMLP-DES) gave a higher yield (improvement of 101.20 %) than citric acid monohydrate (CAM) (MMLP-CAM) and required a lower percentage of microwave power (19.83 % less) and time (0.78 min less). The properties of MMLPs significantly differ based on their pH, molecular weight, viscosity, degree of esterification and monosaccharide molar ratio which influenced the biological activities. Compared to MMLP-CAM, MMLP-DES had a more branched and less linear structure. The bioactivities study revealed that MMLP-DES exhibited higher antioxidant and anti-α-amylase activities (i.e.

    , DPPH: 74.52 %, FRAP: 2.87 mM FeSO4 and α-amylase inhibition: 86.23 %) compared to MMLP-CAM (i.e.

    , DPPH: 49.33 %, FRAP: 1.49 mM FeSO4, and α-amylase inhibition: 81.76 %). The mechanism and structure-activity relationship of MMLPs on bioactivities were also hypothesized.

    SIGNIFICANCE: Based on our previous study, the citric acid monohydrate-glycerol based DES as an extraction medium has enhanced the extraction yield of polysaccharides from M. minutum. This study highlights the DES combined with microwave-assisted extraction to improve the yield of MMLP and evaluate the biological activities compared to CAM as a classical solvent. In conclusion, the DES showed the advantages for extraction of polysaccharides with desired biological activities.

    Matched MeSH terms: alpha-Amylases/antagonists & inhibitors; alpha-Amylases/metabolism
  3. Detection of host-specific immunogenic proteins in the saliva of patients with oral squamous cell carcinoma
    Mu AK, Chan YS, Kang SS, Azman SN, Zain RB, Chai WL, et al.
    J Immunoassay Immunochem, 2014;35(2):183-93.
    PMID: 24295181 DOI: 10.1080/15321819.2013.836535
    The main purpose of this article is to develop a new and reliable saliva-based clinical diagnostic method for the early detection of oral squamous cell carcinoma (OSCC). This study used an immunoproteomic approach which allowed the detection of immunogenic host proteins in patients' samples using pooled human antibodies. In an attempt to investigate potential biomarkers of OSCC, two-dimensional electrophoresis (2-DE) followed by immunoblotting of saliva from patients and controls were compared. The protein spots of interest were analyzed using 2-DE image analyzer and subsequently subjected to MALDI-TOF/TOF and then matched against NCBI database. The result showed that four protein clusters, namely Human Pancreatic Alpha-amylase (HPA), Human Salivary Amylase (sAA), keratin-10 (K-10), and Ga Module Complexed with Human Serum Albumin (GA-HSA), had exhibited immunoreactivity in western blot. The results are suggestive of the potential use of the differentially expressed saliva protein as tumor biomarkers for the detection of OSCC. However, further studies are recommended to validate this finding.
    Matched MeSH terms: Salivary alpha-Amylases/analysis; Salivary alpha-Amylases/immunology; Pancreatic alpha-Amylases/analysis; Pancreatic alpha-Amylases/immunology
  4. Purification and characterization of alpha-amylase from Aspergillus flavus
    Khoo SL, Amirul AA, Kamaruzaman M, Nazalan N, Azizan MN
    Folia Microbiol (Praha), 1994;39(5):392-8.
    PMID: 7729774
    Aspergillus flavus produced approximately 50 U/mL of amylolytic activity when grown in liquid medium with raw low-grade tapioca starch as substrate. Electrophoretic analysis of the culture filtrate showed the presence of only one amylolytic enzyme, identified as an alpha-amylase as evidenced by (i) rapid loss of color in iodine-stained starch and (ii) production of a mixture of glucose, maltose, maltotriose and maltotetraose as starch digestion products. The enzyme was purified by ammonium sulfate precipitation and ion-exchange chromatography and was found to be homogeneous on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The purified enzyme had a molar mass of 52.5 +/- 2.5 kDa with an isoelectric point at pH 3.5. The enzyme was found to have maximum activity at pH 6.0 and was stable in a pH range from 5.0 to 8.5. The optimum temperature for the enzyme was 55 degrees C and it was stable for 1 h up to 50 degrees C. The Km and V for gelatinized tapioca starch were 0.5 g/L and 108.67 mumol reducing sugars per mg protein per min, respectively.
    Matched MeSH terms: alpha-Amylases/isolation & purification*; alpha-Amylases/metabolism; alpha-Amylases/chemistry
  5. Fulltext Functional and Bioactive Properties of Wheat Protein Fractions: Impact of Digestive Enzymes on Antioxidant, α-Amylase, and Angiotensin-Converting Enzyme Inhibition Potential
    Gammoh S, Alu'datt MH, Alhamad MN, Tranchant CC, Rababah T, Al-U'datt D, et al.
    Molecules, 2023 Aug 11;28(16).
    PMID: 37630264 DOI: 10.3390/molecules28166012
    This research aimed to determine the biofunctional properties of wheat flour (WF) protein fractions and modifications to the antioxidant, anti-α-amylase and anti-angiotensin-I converting enzyme (ACE) activities induced by the action of digestive endopeptidases in vitro. A molecular characterization of the most abundant protein fractions, i.e., albumins, glutelins-1, glutelins-2 and prolamins, showed that low- and high-MW polypeptides rich in cysteine, glutamic acid and leucine were present in albumins and glutelins, whereas low-MW subunits with a high proportion of polar amino acids prevailed in prolamins. Prolamins exhibited the second-highest water holding capacity (54%) after WF (84%), while albumins provided superior foam stability (76%). Prolamins, glutenins-1 and globulins demonstrated the highest antioxidant activity (up to 95%, 68% and 59%, respectively) both before and after hydrolysis with pepsin (P-H) or trypsin-chymotrypsin (TC-H). Prolamins, globulins and WF strongly inhibited α-amylase (>90%) before and after TC-H, and before P-H (55-71%). Moreover, P-H significantly increased α-amylase inhibition by albumins from 53 to 74%. The fractions with strong ACE inhibitory activity (70-89%) included prolamins and globulins after TC-H or P-H, as well as globulins before TC-H and WF before P-H. This novel evidence indicates that WF protein fractions and their peptide-enriched P and TC hydrolysates are excellent sources of multifunctional bioactives with antioxidant, antihyperglycemic and antihypertensive potential.
    Matched MeSH terms: alpha-Amylases
  6. Conformational destabilization of Bacillus licheniformis α-amylase induced by lysine modification and calcium depletion
    Tan CY, Rahman RN, Kadir HA, Tayyab S
    Acta Biochim. Pol., 2011;58(3):405-12.
    PMID: 21887412
    Bacillus licheniformis α-amylase (BLA) was chemically modified using 100-fold molar excess of succinic anhydride over protein or 0.66 M potassium cyanate to obtain 42 % succinylated and 81 % carbamylated BLAs. Size and charge homogeneity of modified preparations was established by Sephacryl S-200 HR gel chromatography and polyacrylamide gel electrophoresis. Conformational alteration in these preparations was evident by the larger Stokes radii (3.40 nm for carbamylated and 3.34 nm for succinylated BLAs) compared to 2.43 nm obtained for native BLA. Urea denaturation results using mean residue ellipticity (MRE) as a probe also showed conformational destabilization based on the early start of transition as well as ΔG(D)(H(2)O) values obtained for both modified derivatives and Ca-depleted BLA. Decrease in ΔG(D)(H(2)O) value from 5,930 cal/mol (for native BLA) to 3,957 cal/mol (for succinylated BLA), 3,336 cal/mol (for carbamylated BLA) and 3,430 cal/mol for Ca-depleted BLA suggested reduced conformational stability upon modification of amino groups of BLA or depletion of calcium. Since both succinylation and carbamylation reactions abolish the positive charge on amino groups (both α- and ε- amino), the decrease in conformational stability can be ascribed to the disruption of salt bridges present in the protein which might have released the intrinsic calcium from its binding site.
    Matched MeSH terms: alpha-Amylases/chemistry*
  7. Synthesis, in vitro α-amylase inhibitory, and radicals (DPPH & ABTS) scavenging potentials of new N-sulfonohydrazide substituted indazoles
    Rafique R, Khan KM, Arshia, Chigurupati S, Wadood A, Rehman AU, et al.
    Bioorg Chem, 2020 01;94:103410.
    PMID: 31732193 DOI: 10.1016/j.bioorg.2019.103410
    Over-expression of α-amylase enzyme causes hyperglycemia which lead to many physiological complications including oxidative stress, one of the most commonly associated problem with diabetes mellitus. Marketed α-amylase inhibitors such as acarbose, voglibose, and miglitol used to treat type-II diabetes mellitus, but also linked to several harmful effects. Therefore, it is essential to explore new and nontoxic antidiabetic agents with additional antioxidant properties. In this connection, a series of new N-sulfonohydrazide substituted indazoles 1-19 were synthesized by multistep reaction scheme and assessed for in vitro α-amylase inhibitory and radical (DPPH and ABTS) scavenging properties. All compounds were fully characterized by different spectroscopic techniques including 1H, 13C NMR, EI-MS, HREI-MS, ESI-MS, and HRESI-MS. Compounds showed promising α-amylase inhibitory activities (IC50 = 1.23 ± 0.06-4.5 ± 0.03 µM) as compared to the standard acarbose (IC50 1.20 ± 0.09 µM). In addition to that all derivatives were found good to moderate scavengers of DPPH (IC50 2.01 ± 0.13-5.3 ± 0.11) and ABTS (IC50 = 2.34 ± 0.07-5.5 ± 0.07 µM) radicals, in comparison with standard ascorbic acid having scavenging activities with IC50 = 1.99 ± 0.09 µM, and IC50 2.03 ± 0.11 µM for DPPH and ABTS radicals. In silico molecular docking study was conducted to rationalize the binding interaction of α-amylase enzyme with ligands. Compounds were observed as mixed type inhibitors in enzyme kinetic characterization.
    Matched MeSH terms: alpha-Amylases/antagonists & inhibitors*
  8. Fulltext Immobilization of α-Amylase from Anoxybacillus sp. SK3-4 on ReliZyme and Immobead Supports
    Kahar UM, Sani MH, Chan KG, Goh KM
    Molecules, 2016 Sep 09;21(9).
    PMID: 27618002 DOI: 10.3390/molecules21091196
    α-Amylase from Anoxybacillus sp. SK3-4 (ASKA) is a thermostable enzyme that produces a high level of maltose from starches. A truncated ASKA (TASKA) variant with improved expression and purification efficiency was characterized in an earlier study. In this work, TASKA was purified and immobilized through covalent attachment on three epoxide (ReliZyme EP403/M, Immobead IB-150P, and Immobead IB-150A) and an amino-epoxide (ReliZyme HFA403/M) activated supports. Several parameters affecting immobilization were analyzed, including the pH, temperature, and quantity (mg) of enzyme added per gram of support. The influence of the carrier surface properties, pore sizes, and lengths of spacer arms (functional groups) on biocatalyst performances were studied. Free and immobilized TASKAs were stable at pH 6.0-9.0 and active at pH 8.0. The enzyme showed optimal activity and considerable stability at 60 °C. Immobilized TASKA retained 50% of its initial activity after 5-12 cycles of reuse. Upon degradation of starches and amylose, only immobilized TASKA on ReliZyme HFA403/M has comparable hydrolytic ability with the free enzyme. To the best of our knowledge, this is the first report of an immobilization study of an α-amylase from Anoxybacillus spp. and the first report of α-amylase immobilization using ReliZyme and Immobeads as supports.
    Matched MeSH terms: alpha-Amylases/chemistry*
  9. Purification of exopolysaccharide produced from Lactobacillus spp. using ionic-liquid as adjuvant in alcohol/salt-based aqueous two-phase system for its antidiabetic properties
    Raj ST, Puspanadan S, Gan CY, Tan JS
    Int J Biol Macromol, 2024 May;267(Pt 2):131376.
    PMID: 38608981 DOI: 10.1016/j.ijbiomac.2024.131376
    Diabetes is a chronic, metabolic disease characterized by hyperglycemia resulting from either insufficient insulin production or impaired cellular response to insulin. Exopolysaccharides (EPS) produced by Lactobacillus spp. demonstrated promising therapeutic potential in terms of their anti-diabetic properties. Extraction and purification of EPS produced by Lactobacillus acidophilus and Limosilactobacillus reuteri were performed using ethanol precipitation, followed by alcohol/salt based aqueous two-phase system (ATPS). The purification process involved ethanol precipitation followed by an alcohol/salt-based ATPS. The study systematically investigated various purification parameters in ATPS, including ethanol concentration, type and concentration of ionic liquid, type and concentration of salt and pH of salt. Purified EPS contents from L. acidophilus (63.30 μg/mL) and L. reuteri (146.48 μg/mL) were obtained under optimum conditions of ATPS which consisted of 30 % (w/w) ethanol, 25 % (w/w) dipotassium hydrogen phosphate at pH 10 and 2 % (w/w) 1-butyl-3-methylimidazolium octyl sulfate. The extracted EPS content was determined using phenol sulphuric acid method. In α-amylase inhibition tests, the inhibitory rate was found to be 92.52 % (L. reuteri) and 90.64 % (L. acidophilus), while in α-glucosidase inhibition tests, the inhibitory rate was 73.58 % (L. reuteri) and 68.77 % (L. acidophilus), based on the optimized parameters selected in ATPS. These results suggest that the purified EPS derived from the postbiotics of Lactobacillus spp. hold promise as potential antidiabetic agents.
    Matched MeSH terms: alpha-Amylases/antagonists & inhibitors
  10. Experimental and computational approaches to reveal the potential of Ficus deltoidea leaves extract as α-amylase inhibitor
    Abu Bakar AR, Manaharan T, Merican AF, Mohamad SB
    Nat Prod Res, 2018 Feb;32(4):473-476.
    PMID: 28391727 DOI: 10.1080/14786419.2017.1312393
    Ficus deltoidea leaves extract are known to have good therapeutic properties such as antioxidant, anti-inflammatory and anti-diabetic. We showed that 50% ethanol-water extract of F. deltoidea leaves and its pungent compounds vitexin and isovitexin exhibited significant (p 
    Matched MeSH terms: alpha-Amylases/antagonists & inhibitors*; alpha-Amylases/metabolism; alpha-Amylases/chemistry
  11. Complex Copy Number Variation of AMY1 does not Associate with Obesity in two East Asian Cohorts
    Yong RY, Mustaffa SB, Wasan PS, Sheng L, Marshall CR, Scherer SW, et al.
    Hum Mutat, 2016 Jul;37(7):669-78.
    PMID: 27068483 DOI: 10.1002/humu.22996
    The human amylase gene locus at chromosome 1p21.1 is structurally complex. This region contains two pancreatic amylase genes, AMY2B, AMY2A, and a salivary gene AMY1. The AMY1 gene harbors extensive copy number variation (CNV), and recent studies have implicated this variation in adaptation to starch-rich diets and in association to obesity for European and Asian populations. In this study, we showed that by combining quantitative PCR and digital PCR, coupled with careful experimental design and calibration, we can improve the resolution of genotyping CNV with high copy numbers (CNs). In two East Asian populations of Chinese and Malay ethnicity studied, we observed a unique non-normal distribution of AMY1 diploid CN genotypes with even:odd CNs ratio of 4.5 (3.3-4.7), and an association between the common AMY2A CN = 2 genotype and odd CNs of AMY1, that could be explained by the underlying haplotypic structure. In two further case-control cohorts (n = 932 and 145, for Chinese and Malays, respectively), we did not observe the previously reported association between AMY1 and obesity or body mass index. Improved methods for accurately genotyping multiallelic CNV loci and understanding the haplotype complexity at the AMY1 locus are necessary for population genetics and association studies.
    Matched MeSH terms: Salivary alpha-Amylases/genetics*; Pancreatic alpha-Amylases/genetics
  12. Fulltext Molten globule-like partially folded state of Bacillus licheniformis α-amylase at low pH induced by 1,1,1,3,3,3-hexafluoroisopropanol
    Abd Halim AA, Zaroog MS, Kadir HA, Tayyab S
    ScientificWorldJournal, 2014;2014:824768.
    PMID: 24977228 DOI: 10.1155/2014/824768
    Effect of 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) on acid-denatured Bacillus licheniformis α -amylase (BLA) at pH 2.0 was investigated by far-UV CD, intrinsic fluorescence, and ANS fluorescence measurements. Addition of increasing HFIP concentrations led to an increase in the mean residue ellipticity at 222 nm (MRE 222 nm) up to 1.5 M HFIP concentration beyond which it sloped off. A small increase in the intrinsic fluorescence and a marked increase in the ANS fluorescence were also observed up to 0.4 M HFIP concentration, both of which decreased thereafter. Far- and near-UV CD spectra of the HFIP-induced state observed at 0.4 M HFIP showed significant retention of the secondary structures closer to native BLA but a disordered tertiary structure. Increase in the ANS fluorescence intensity was also observed with the HFIP-induced state, suggesting exposure of the hydrophobic clusters to the solvent. Furthermore, thermal denaturation of HFIP-induced state showed a non-cooperative transition. Taken together, all these results suggested that HFIP-induced state of BLA represented a molten globule-like state at pH 2.0.
    Matched MeSH terms: alpha-Amylases/ultrastructure*; alpha-Amylases/chemistry*
  13. Hydrolysis of native and heat-treated starches at sub-gelatinization temperature using granular starch hydrolyzing enzyme
    Uthumporn U, Shariffa YN, Karim AA
    Appl Biochem Biotechnol, 2012 Mar;166(5):1167-82.
    PMID: 22203397 DOI: 10.1007/s12010-011-9502-x
    The effect of heat treatment below the gelatinization temperature on the susceptibility of corn, mung bean, sago, and potato starches towards granular starch hydrolysis (35°C) was investigated. Starches were hydrolyzed in granular state and after heat treatment (50°C for 30 min) by using granular starch hydrolyzing enzyme for 24 h. Hydrolyzed heat-treated starches showed a significant increase in the percentage of dextrose equivalent compared to native starches, respectively, with corn 53% to 56%, mung bean 36% to 47%, sago 15% to 26%, and potato 12% to 15%. Scanning electron microscopy micrographs showed the presence of more porous granules and surface erosion in heat-treated starch compared to native starch. X-ray analysis showed no changes but with sharper peaks for all the starches, suggested that hydrolysis occurred on the amorphous region. The amylose content and swelling power of heat-treated starches was markedly altered after hydrolysis. Evidently, this enzyme was able to hydrolyze granular starches and heat treatment before hydrolysis significantly increased the degree of hydrolysis.
    Matched MeSH terms: alpha-Amylases/metabolism*; alpha-Amylases/chemistry
  14. Fulltext Expression and Characterization of Geobacillus stearothermophilus SR74 Recombinant α-Amylase in Pichia pastoris
    Gandhi S, Salleh AB, Rahman RN, Chor Leow T, Oslan SN
    Biomed Res Int, 2015;2015:529059.
    PMID: 26090417 DOI: 10.1155/2015/529059
    Geobacillus stearothermophilus SR74 is a locally isolated thermophilic bacteria producing thermostable and thermoactive α-amylase. Increased production and commercialization of thermostable α-amylase strongly warrant the need of a suitable expression system. In this study, the gene encoding the thermostable α-amylase in G. stearothermophilus SR74 was amplified, sequenced, and subcloned into P. pastoris GS115 strain under the control of a methanol inducible promoter, alcohol oxidase (AOX). Methanol induced recombinant expression and secretion of the protein resulted in high levels of extracellular amylase production. YPTM medium supplemented with methanol (1% v/v) was the best medium and once optimized, the maximum recombinant α-amylase SR74 achieved in shake flask was 28.6 U mL(-1) at 120 h after induction. The recombinant 59 kDa α-amylase SR74 was purified 1.9-fold using affinity chromatography with a product yield of 52.6% and a specific activity of 151.8 U mg(-1). The optimum pH of α-amylase SR74 was 7.0 and the enzyme was stable between pH 6.0-8.0. The purified enzyme was thermostable and thermoactive, exhibiting maximum activity at 65°C with a half-life (t₁/₂) of 88 min at 60°C. In conclusion, thermostable α-amylase SR74 from G. stearothermophilus SR74 would be beneficial for industrial applications, especially in liquefying saccrification.
    Matched MeSH terms: alpha-Amylases/biosynthesis; alpha-Amylases/genetics*
  15. Cloning and characterization of two new thermostable and alkalitolerant α-amylases from the Anoxybacillus species that produce high levels of maltose
    Chai YY, Rahman RN, Illias RM, Goh KM
    J Ind Microbiol Biotechnol, 2012 May;39(5):731-41.
    PMID: 22246222 DOI: 10.1007/s10295-011-1074-9
    Two genes that encode α-amylases from two Anoxybacillus species were cloned and expressed in Escherichia coli. The genes are 1,518 bp long and encode 506 amino acids. Both sequences are 98% similar but are distinct from other well-known α-amylases. Both of the recombinant enzymes, ASKA and ADTA, were purified using an α-CD-Sepharose column. They exhibited an optimum activity at 60°C and pH 8. Both amylases were stable at pH 6-10. At 60°C in the absence of Ca²⁺, negligible reduction in activity for up to 48 h was observed. The activity half-life at 65°C was 48 and 3 h for ASKA and ADTA, respectively. In the presence of Ca²⁺ ions, both amylases were highly stable for at least 48 h and had less than a 10% decrease in activity at 70°C. Both enzymes exhibited similar end-product profiles, and the predominant yield was maltose (69%) from starch hydrolysis. To the best of our knowledge, most α-amylases that produce high levels of maltose are active at an acidic to neutral pH. This is the first report of two thermostable, alkalitolerant recombinant α-amylases from Anoxybacillus that produce high levels of maltose and have an atypical protein sequence compared with known α-amylases.
    Matched MeSH terms: alpha-Amylases/genetics; alpha-Amylases/metabolism*
  16. Crystal structure of a compact α-amylase from Geobacillus thermoleovorans
    Mok SC, Teh AH, Saito JA, Najimudin N, Alam M
    Enzyme Microb Technol, 2013 Jun 10;53(1):46-54.
    PMID: 23683704 DOI: 10.1016/j.enzmictec.2013.03.009
    A truncated form of an α-amylase, GTA, from thermophilic Geobacillus thermoleovorans CCB_US3_UF5 was biochemically and structurally characterized. The recombinant GTA, which lacked both the N- and C-terminal transmembrane regions, functioned optimally at 70°C and pH 6.0. While enzyme activity was not enhanced by the addition of CaCl2, GTA's thermostability was significantly improved in the presence of CaCl2. The structure, in complex with an acarbose-derived pseudo-hexasaccharide, consists of the typical three domains and binds one Ca(2+) ion. This Ca(2+) ion was strongly bound and not chelated by EDTA. A predicted second Ca(2+)-binding site, however, was disordered. With limited subsites, two novel substrate-binding residues, Y147 and Y182, may help increase substrate affinity. No distinct starch-binding domain is present, although two regions rich in aromatic residues have been observed. GTA, with a smaller domain B and several shorter loops compared to other α-amylases, has one of the most compact α-amylase folds that may contribute greatly to its tight Ca(2+) binding and thermostability.
    Matched MeSH terms: alpha-Amylases/metabolism*; alpha-Amylases/chemistry*
  17. Synthesis of alpha amylase inhibitors based on privileged indole scaffold
    Noreen T, Taha M, Imran S, Chigurupati S, Rahim F, Selvaraj M, et al.
    Bioorg Chem, 2017 06;72:248-255.
    PMID: 28482265 DOI: 10.1016/j.bioorg.2017.04.010
    Twenty five derivatives of indole carbohydrazide (1-25) had been synthesized. These compounds were characterized using 1H NMR and EI-MS, and further evaluated for their α-amylase inhibitory potential. The analogs (1-25) showed varying degree of α-amylase inhibitory potential. ranging between 9.28 and 599.0µM when compared with standard acarbose having IC50 value 8.78±0.16µM. Six analogs, 25 (IC50=9.28±0.153µM), 22 (IC50=9.79±0.43µM), 4 (IC50=11.08±0.357µM), 1 (IC50=12.65±0.169µM), 8 (IC50=21.37±0.07µM) and 14 (IC50=43.21±0.14µM) showed potent α-amylase inhibition as compared to the standard acarbose (IC50=8.78±0.16µM). All other analogs displayed good to moderate inhibitory potential. Structure-activity relationship was established through the interaction of the active compounds with enzyme active site with the help of docking studies.
    Matched MeSH terms: alpha-Amylases/antagonists & inhibitors*; alpha-Amylases/metabolism
  18. Synthesis and biological evaluation of indole derivatives as α-amylase inhibitor
    Imran S, Taha M, Selvaraj M, Ismail NH, Chigurupati S, Mohammad JI
    Bioorg Chem, 2017 08;73:121-127.
    PMID: 28648924 DOI: 10.1016/j.bioorg.2017.06.007
    A series of twenty indole hydrazone analogs (1-21) were synthesized, characterized by different spectroscopic techniques such as 1H NMR and EI-MS, and screened for α-amylase inhibitory activity. All analogs showed a variable degree of α-amylase inhibition with IC50 values ranging between 1.66 and 2.65μM. Nine compounds that are 1 (2.23±0.01μM), 8 (2.44±0.12μM), 10 (1.92±0.12μM), 12 (2.49±0.17μM), 13 (1.66±0.09μM), 17 (2.25±0.1μM), 18 (1.87±0.25μM), 20 (1.83±0.63μM), and 19 (1.97±0.02μM) showed potent α-amylase inhibition when compared with the standard acarbose (1.05±0.29μM). Other analogs showed good to moderate α-amylase inhibition. The structure activity relationship is mainly focusing on difference of substituents on phenyl part. Molecular docking studies were carried out to understand the binding interaction of the most active compounds.
    Matched MeSH terms: alpha-Amylases/antagonists & inhibitors*; alpha-Amylases/metabolism
  19. 2'-Aryl and 4'-arylidene substituted pyrazolones: As potential α-amylase inhibitors
    Yousuf S, Khan KM, Salar U, Chigurupati S, Muhammad MT, Wadood A, et al.
    Eur J Med Chem, 2018 Nov 05;159:47-58.
    PMID: 30268823 DOI: 10.1016/j.ejmech.2018.09.052
    Acarbose and voglibose are well-known α-amylase inhibitors used for the management of type-II diabetes mellitus. Unfortunately, these well-known and clinically used inhibitors are also associated with several adverse effects. Therefore, there is still need to develop the safer therapy. Despite of a broad spectrum of biological significances of pyrazolone, it is infrequently evaluated for α-amylase inhibition. Current study deals with the synthesis and biological screening of aryl and arylidene substituted pyrazolones 1-18 for their potential α-amylase inhibitory activity. Structures of synthetic derivatives 1-18 were identified by different spectroscopic techniques. All compounds 1-18 (IC50 = 1.61 ± 0.16 μM to 2.38 ± 0.09 μM) exhibited significant to moderate inhibitory potential when compared to standard acarbose (IC50 = 1.46 ± 0.26 μM). A number of derivatives including 8-12 (IC50 = 1.68 ± 0.1 μM to 1.97 ± 0.07 μM) and 14-16 (IC50 = 1.61 ± 0.16 μM to 1.93 ± 0.07 μM) were found to be significantly active. Limited SAR suggested that different substitutions on compounds do not have any significant effect on the inhibitory potential. Compounds were found to be mixed-type inhibitors revealed by kinetic studies. However, in silico study was identified a number of key features participating in the interaction with the binding site of α-amylase enzyme.
    Matched MeSH terms: alpha-Amylases/antagonists & inhibitors*; alpha-Amylases/metabolism
  20. Fulltext Potential Roles of α-amylase in Alzheimer's Disease: Biomarker and Drug Target
    Chen WN, Tang KS, Yeong KY
    Curr Neuropharmacol, 2022;20(8):1554-1563.
    PMID: 34951390 DOI: 10.2174/1570159X20666211223124715
    Alzheimer's disease (AD), the most common form of dementia, is pathologically characterized by the deposition of amyloid-β plaques and the formation of neurofibrillary tangles. In a neurodegenerative brain, glucose metabolism is also impaired and considered as one of the key features in AD patients. The impairment causes a reduction in glucose transporters and the uptake of glucose as well as alterations in the specific activity of glycolytic enzymes. Recently, it has been reported that α-amylase, a polysaccharide-degrading enzyme, is present in the human brain. The enzyme is known to be associated with various diseases such as type 2 diabetes mellitus and hyperamylasaemia. With this information at hand, we hypothesize that α-amylase could have a vital role in the demented brains of AD patients. This review aims to shed insight into the possible link between the expression levels of α-amylase and AD. Lastly, we also cover the diverse role of amylase inhibitors and how they could serve as a therapeutic agent to manage or stop AD progression.
    Matched MeSH terms: alpha-Amylases/metabolism; alpha-Amylases/therapeutic use
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