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Profil pengekspresan gen mengekod delta 6 dan delta 12-asid lemak Desaturase Cunninghamella Bainieri semasa Biosintesis asid Gamma-Linolenik

Noor Adila Abdul Karim, Zamri Zainal, Aidil Abdul Hamid, Farah Diba Abu Bakar, Abdul Munir Abdul Murad

Sains Malaysiana, 2016;45:1443-1451.

Delta 6-asid lemak desaturase dan delta 12-asid lemak desaturase merupakan enzim yang diperlukan bagi langkah desaturasi semasa proses biosintesis asid gamma-linolenik (GLA) oleh kulat oleaginus. Objektif kajian ini ialah untuk menganalisis profil pengekspresan gen mengekod enzim delta 6-asid lemak desaturase (des6) dan delta 12-asid lemak desaturase (des12) kulat oleaginus Cunninghamella bainieri semasa penghasilan GLA. Jujukan gen separa bersaiz 1372 pb bagi des6 dan 1008 pb bagi des12 telah dipencil daripada C. bainieri. Analisis pengekspresan gen menggunakan kaedah tindak balas berantai polimerase kuantitatif masa sebenar (RT-qPCR) menunjukkan perubahan kadar pengekspresan des6 adalah lebih tinggi berbanding kadar pengekspresan des12 semasa penghasilan GLA. Pengekspresan des6 adalah tertinggi selepas 24 jam dikultur dalam medium penghasilan GLA. Namun, kadar pengekspresannya menurun hingga jam ke-96 pertumbuhan tetapi meningkat semula pada jam ke-120. Bagi des12, kadar pengekspresannya adalah lebih sekata dengan pengekspresan tertinggi dikesan pada jam ke-120. Analisis penghasilan GLA menunjukkan jumlah GLA dalam sel berkolerasi dengan kadar pengekspresan des6. Hasil kajian mencadangkan bahawa aras pengekspresan des6 adalah penting dalam menentukan aras GLA dalam C. bainieri.

Matched MeSH terms: Dipeptides
Fulltext A novel sequence-based predictor for identifying and characterizing thermophilic proteins using estimated propensity scores of dipeptides

Charoenkwan P, Chotpatiwetchkul W, Lee VS, Nantasenamat C, Shoombuatong W

Sci Rep, 2021 Dec 10;11(1):23782.
PMID: 34893688 DOI: 10.1038/s41598-021-03293-w

Owing to their ability to maintain a thermodynamically stable fold at extremely high temperatures, thermophilic proteins (TTPs) play a critical role in basic research and a variety of applications in the food industry. As a result, the development of computation models for rapidly and accurately identifying novel TTPs from a large number of uncharacterized protein sequences is desirable. In spite of existing computational models that have already been developed for characterizing thermophilic proteins, their performance and interpretability remain unsatisfactory. We present a novel sequence-based thermophilic protein predictor, termed SCMTPP, for improving model predictability and interpretability. First, an up-to-date and high-quality dataset consisting of 1853 TPPs and 3233 non-TPPs was compiled from published literature. Second, the SCMTPP predictor was created by combining the scoring card method (SCM) with estimated propensity scores of g-gap dipeptides. Benchmarking experiments revealed that SCMTPP had a cross-validation accuracy of 0.883, which was comparable to that of a support vector machine-based predictor (0.906-0.910) and 2-17% higher than that of commonly used machine learning models. Furthermore, SCMTPP outperformed the state-of-the-art approach (ThermoPred) on the independent test dataset, with accuracy and MCC of 0.865 and 0.731, respectively. Finally, the SCMTPP-derived propensity scores were used to elucidate the critical physicochemical properties for protein thermostability enhancement. In terms of interpretability and generalizability, comparative results showed that SCMTPP was effective for identifying and characterizing TPPs. We had implemented the proposed predictor as a user-friendly online web server at http://pmlabstack.pythonanywhere.com/SCMTPP in order to allow easy access to the model. SCMTPP is expected to be a powerful tool for facilitating community-wide efforts to identify TPPs on a large scale and guiding experimental characterization of TPPs.

Matched MeSH terms: Dipeptides/metabolism; Dipeptides/chemistry*
Synthesis of dipeptide benzoylalanylglycine methyl ester and corrosion inhibitor evaluation by tafel equation

Abdurrahman J, Wahyuningrum D, Achmad S, Bundjali B

Sains Malaysiana, 2011;40.

Corrosion is one of the major problems in petroleum mining and processing industry. The pipelines used to transport crude oil from reservoir to the processing installation were made from carbon steel that is susceptible towards corrosion. One of the best methods to prevent corrosion that occurred at the inner parts of carbon steel pipelines is to use organic corrosion inhibitor. One of the potent organic corrosion inhibitors is amino acids derivatives. In this study, dipeptide compound namely benzoylalanylglycine methyl ester and benzoylalanylglycine have been synthesized. The structure elucidation of the products was performed by IR, MS and NMR spectroscopy. The determination of corrosion inhibition activity utilized the Tafel method. The corrosion inhibition efficiency of glycine methyl ester, benzoylalanine, dipeptide benzoylalanylglycine methyl ester and dipeptide benzoylalanylglycine were 63.34%, 35.86%, 68.40% and 27.72%, respectively. These results showed that the formation of dipeptide benzoylalanylglycine methyl ester, derived from carboxylic protected glycine and amine protected alanine, increased the corrosion inhibition activity due to the loss of acidity center in the structure of glicine and L-alanine that would induce the corrosive environment towards carbon steel.

Matched MeSH terms: Dipeptides
Fulltext Suppression of Human T Cell Proliferation Mediated by the Cathepsin B Inhibitor, z-FA-FMK Is Due to Oxidative Stress

Rajah T, Chow SC

PLoS One, 2015;10(4):e0123711.
PMID: 25915766 DOI: 10.1371/journal.pone.0123711

The cathepsin B inhibitor, benzyloxycarbonyl-phenylalanine-alanine-fluoromethyl ketone (z-FA-FMK) readily inhibits anti-CD3-induced human T cell proliferation, whereas the analogue benzyloxycarbonyl-phenylalanine-alanine-diazomethyl ketone (z-FA-DMK) had no effect. In contrast, benzyloxycarbonyl-phenylalanine-alanine-chloromethyl ketone (z-FA-CMK) was toxic. The inhibition of T cell proliferation mediated by z-FA-FMK requires not only the FMK moiety, but also the benzyloxycarbonyl group at the N-terminal, suggesting some degree of specificity in z-FA-FMK-induced inhibition of primary T cell proliferation. We showed that z-FA-FMK treatment leads to a decrease in intracellular glutathione (GSH) with a concomitant increase in reactive oxygen species (ROS) levels in activated T cells. The inhibition of anti-CD3-induced T cell proliferation mediated by z-FA-FMK was abolished by the presence of low molecular weight thiols such as GSH, N-acetylcysteine (NAC) and L-cysteine, whereas D-cysteine which cannot be metabolised to GSH has no effect. The inhibition of anti-CD3-induced up-regulation of CD25 and CD69 expression mediated by z-FA-FMK was also attenuated in the presence of exogenous GSH. Similar to cell proliferation, GSH, NAC and L-cysteine but not D-cysteine, completely restored the processing of caspase-8 and caspase-3 to their respective subunits in z-FA-FMK-treated activated T cells. Our collective results demonstrated that the inhibition of T cell activation and proliferation mediated by z-FA-FMK is due to oxidative stress via the depletion of GSH.

Matched MeSH terms: Dipeptides/pharmacology*
Synthesis of potent urease inhibitors based on disulfide scaffold and their molecular docking studies

Taha M, Ismail NH, Imran S, Wadood A, Rahim F, Riaz M

Bioorg Med Chem, 2015 Nov 15;23(22):7211-8.
PMID: 26507431 DOI: 10.1016/j.bmc.2015.10.017

Disulfide analogs (1-20) have been synthesized, characterized by HR-MS, (1)H NMR and (13)C NMR and screened for urease inhibitory potential. All compounds were found to have varied degree of urease inhibitory potential ranging in between 0.4 ± 0.01 and 18.60 ± 1.24 μM when compared with standard inhibitor thiourea with IC50 19.46 ± 1.20 μM. Structure activity relationship has been established. The binding interactions of compounds with enzyme were confirmed through molecular docking. All the synthesized compounds 1-20 are new. Our compounds are cheaply synthesizable with high yield and can further be studied to discovery lead compounds. We further, tested for carbonic anhydrase, PDE1 and butyrylcholinesterase but they show no activity. On the other hand we evaluated all compounds for cytotoxicity they showed no toxicity.

Matched MeSH terms: Dipeptides
Fulltext Periscope: quantitative prediction of soluble protein expression in the periplasm of Escherichia coli

Chang CC, Li C, Webb GI, Tey B, Song J, Ramanan RN

Sci Rep, 2016;6:21844.
PMID: 26931649 DOI: 10.1038/srep21844

Periplasmic expression of soluble proteins in Escherichia coli not only offers a much-simplified downstream purification process, but also enhances the probability of obtaining correctly folded and biologically active proteins. Different combinations of signal peptides and target proteins lead to different soluble protein expression levels, ranging from negligible to several grams per litre. Accurate algorithms for rational selection of promising candidates can serve as a powerful tool to complement with current trial-and-error approaches. Accordingly, proteomics studies can be conducted with greater efficiency and cost-effectiveness. Here, we developed a predictor with a two-stage architecture, to predict the real-valued expression level of target protein in the periplasm. The output of the first-stage support vector machine (SVM) classifier determines which second-stage support vector regression (SVR) classifier to be used. When tested on an independent test dataset, the predictor achieved an overall prediction accuracy of 78% and a Pearson's correlation coefficient (PCC) of 0.77. We further illustrate the relative importance of various features with respect to different models. The results indicate that the occurrence of dipeptide glutamine and aspartic acid is the most important feature for the classification model. Finally, we provide access to the implemented predictor through the Periscope webserver, freely accessible at http://lightning.med.monash.edu/periscope/.

Matched MeSH terms: Dipeptides
Fulltext Kombiglyze (metformin and saxagliptin)-induced hepatotoxicity in a patient with non-alcoholic fatty liver disease

Thalha AM, Mahadeva S, Boon Tan AT, Mun KS

JGH Open, 2018 Oct;2(5):242-245.
PMID: 30483596 DOI: 10.1002/jgh3.12083

A 33-year-old man was referred with hyperosmotic symptoms of 4 weeks. Clinical examination showed palpable hepatomegaly and no stigmata of liver disease. Findings were random glucose 16.6 mmol/L, HbA1c 12.4%, triglyceride 6.2 mmol/L, normal LFTs and ultrasound liver: increased echogenicity. Management consisted of dietician referral and commencement of metformin 500 mg bd, diamicron MR 60 mg od, and fenofibrate 145 mg od. He was non-compliant, complaining of "heaviness of head" after consuming oral diabetic agents, without symptoms of hypoglycemia. Treatment was switched to Kombiglyze XR (saxaglipitin 5 mg + metformin 1000 mg) and empagliflozin 25 mg od. He presented 1 week later with generalised pruritus with ALT 307 IU/L and serum GGT 808 IU/L. Following this, a percutaneous liver biopsy was performed, revealing steatohepatitis and marked intra-hepatic cholestasis. Kombiglyze XR was withheld, with resolution of LFTs to baseline. Phenotypes of liver injury are categorised according to R value, defined as ratio ALT/ULN:ALP/ULN. R value of ≥5:hepatocellular injury, ≤2:cholestatic injury, 2-5:mixed-type injury. Here, R value points toward mixed type (R = 3.203). Hepatotoxicity in patients with NASH is difficult to diagnose, based on laboratory parameters. Liver histology was useful in indicating additional changes apart from NASH, causing liver derangement. The Rousal Uclaf Causality Assessment Method is a scoring method to determine the probability of drug induced liver injury. RUCAM score for this case was 6 (probable adverse drug reaction). Hepatotoxicity from saxagliptin not been reported prior. Clinicians need to be more vigilant, particularly in patients with NASH.

Matched MeSH terms: Dipeptides
Fulltext Cellular Metabolic Profiling of CrFK Cells Infected with Feline Infectious Peritonitis Virus Using Phenotype Microarrays

Ng SW, Selvarajah GT, Cheah YK, Mustaffa Kamal F, Omar AR

Pathogens, 2020 May 25;9(5).
PMID: 32466289 DOI: 10.3390/pathogens9050412

Feline infectious peritonitis (FIP) is a fatal feline immune-mediated disease caused by feline infectious peritonitis virus (FIPV). Little is known about the biological pathways associated in FIP pathogenesis. This is the first study aiming to determine the phenotypic characteristics on the cellular level in relation to specific metabolic pathways of importance to FIP pathogenesis.
METHODS: The internalization of type II FIPV WSU 79-1146 in Crandell-Rees Feline Kidney (CrFK) cells was visualized using a fluorescence microscope, and optimization prior to phenotype microarray (PM) study was performed. Then, four types of Biolog Phenotype MicroArray™ plates (PM-M1 to PM-M4) precoated with different carbon and nitrogen sources were used to determine the metabolic profiles in FIPV-infected cells.
RESULTS: The utilization of palatinose was significantly low in FIPV-infected cells; however, there were significant increases in utilizing melibionic acid, L-glutamine, L-glutamic acid and alanyl-glutamine (Ala-Gln) compared to non-infected cells.
CONCLUSION: This study has provided the first insights into the metabolic profiling of a feline coronavirus infection in vitro using PMs and deduced that glutamine metabolism is one of the essential metabolic pathways for FIPV infection and replication. Further studies are necessary to develop strategies to target the glutamine metabolic pathway in FIPV infection.

Matched MeSH terms: Dipeptides
Fulltext Antibody-dependent cellular phagocytosis of tropomyosin receptor kinase C (TrkC) expressing cancer cells for targeted immunotherapy

Lai PS, Usama SM, Kiew LV, Lee HB, Chung LY, Burgess K, et al.

Cancer Immunol Immunother, 2022 Sep;71(9):2099-2108.
PMID: 35032175 DOI: 10.1007/s00262-022-03147-y

Conventional cancer therapies such as chemotherapy are non-selective and induce immune system anergy, which lead to serious side effects and tumor relapse. It is a challenge to prime the body's immune system in the cancer-bearing subject to produce cancer antigen-targeting antibodies, as most tumor-associated antigens are expressed abundantly in cancer cells and some of normal cells. This study illustrates how hapten-based pre-immunization (for anti-hapten antibodies production) combined with cancer receptor labeling with hapten antigen constructs can elicit antibody-dependent cellular phagocytosis (ADCP). Thus, the hapten antigen 2,4-dinitrophenol (DNP) was covalently combined with a cancer receptor-binding dipeptide (IYIY) to form a dipeptide-hapten construct (IYIY-DNP, MW = 1322.33) that targets the tropomyosin receptor kinase C (TrkC)-expressed on the surface of metastatic cancer cells. IYIY-DNP facilitated selective association of RAW264.7 macrophages to the TrkC expressing 4T1 cancer cells in vitro, forming cell aggregates in the presence of anti-DNP antibodies, suggesting initiation of anti-DNP antibody-dependent cancer cell recognition of macrophages by the IYIY-DNP. In in vivo, IYIY-DNP at 10 mg/kg suppressed growth of 4T1 tumors in DNP-immunized BALB/c mice by 45% (p

Matched MeSH terms: Dipeptides
TP53 Gene 72 Arg/Pro (rs1042522) Single Nucleotide Polymorphism Contribute to Increase the Risk of B-Chronic Lymphocytic Leukemia in the Sudanese Population

Mohammed Basabaeen AA, Abdelgader EA, Babekir EA, Abdelrahim SO, Eltayeb NH, Altayeb OA, et al.

Asian Pac J Cancer Prev, 2019 May 25;20(5):1579-1585.
PMID: 31128065

Objective: This study aimed at exploring the association of TP53 72Arg/Pro polymorphism and Risk of Chronic
Lymphocytic Leukemia and to assess the correlation between TP53 72Arg/Pro polymorphism and clinical parameter,
hematological profile and some biological prognostic markers among Sudanese patients with chronic lymphocytic
leukemia. Methods: A case-control study was conducted in Khartoum state, Sudan, during the period from April 2017 to
April 2018, involved 110 B-CLL patients and 80 healthy volunteers as a control group. Physical examination, Complete
Blood Count and Immunophenotype were performed in all patients to confirm the diagnosis. Clinical staging such as
Rai and Binet were studied. CD38 and ZAP70 were performed by Flow Cytometry. Blood samples were collected from
all participants; DNA was extracted by using ANALYTIKJENA Blood DNA Extraction Kit (Germany) and analyzed
TP53 codon 72Arg/Pro Polymorphism by using AS-PCR. The statistical analysis was performed using SPSS version
23.0 software (Chicago, IL, USA). Results: the Arg/Pro was the most frequent genotype in B-CLL patients(50%),
followed by Arg/Arg (25.5%) and Pro/Pro (24.5%), whereas in healthy control group Arg/Pro was the most frequent
(47.5%), followed by Arg/Arg (45%) and Pro/Pro (7.5%). Our data indicate a higher frequency of homozygous Pro/
Pro in the B-CLL patients as compared to controls with an OR of 4.01 for the Pro/Pro genotype and lower frequency
of Arg/Arg genotype in CLL patients as compared to controls with an OR of .42 for the Arg/Arg genotype. Also, the
Pro allele showed higher risk than Arg allele (P value=0.000, OR 2.23, 95% CI=1.45-3.41). No significant association
between gender, clinical staging systems (Rai, Binet), biological prognostic markers (CD38 expression or ZAP70
expression), and TP53 codon 72Arg/Pro polymorphisms, except Arg/Arg genotype tended to be associated with younger
age (P =0.04). Conclusion: Our data suggested that Pro/Pro genotype contribute to increased susceptibility to B-Chronic
Lymphocytic Leukemia risk in our population tenfold higher than those had Arg/Arg genotype.

Matched MeSH terms: Dipeptides/genetics*
Neurometabolites Alteration in the Acute Phase of Mild Traumatic Brain Injury (mTBI): An In Vivo Proton Magnetic Resonance Spectroscopy (1H-MRS) Study

Veeramuthu V, Seow P, Narayanan V, Wong JHD, Tan LK, Hernowo AT, et al.

Acad Radiol, 2018 09;25(9):1167-1177.
PMID: 29449141 DOI: 10.1016/j.acra.2018.01.005

RATIONALE AND OBJECTIVES: Magnetic resonance spectroscopy is a noninvasive imaging technique that allows for reliable assessment of microscopic changes in brain cytoarchitecture, neuronal injuries, and neurochemical changes resultant from traumatic insults. We aimed to evaluate the acute alteration of neurometabolites in complicated and uncomplicated mild traumatic brain injury (mTBI) patients in comparison to control subjects using proton magnetic resonance spectroscopy (1H magnetic resonance spectroscopy).
MATERIAL AND METHODS: Forty-eight subjects (23 complicated mTBI [cmTBI] patients, 12 uncomplicated mTBI [umTBI] patients, and 13 controls) underwent magnetic resonance imaging scan with additional single voxel spectroscopy sequence. Magnetic resonance imaging scans for patients were done at an average of 10 hours (standard deviation 4.26) post injury. The single voxel spectroscopy adjacent to side of injury and noninjury regions were analysed to obtain absolute concentrations and ratio relative to creatine of the neurometabolites. One-way analysis of variance was performed to compare neurometabolite concentrations of the three groups, and a correlation study was done between the neurometabolite concentration and Glasgow Coma Scale.
RESULTS: Significant difference was found in ratio of N-acetylaspartate to creatine (NAA/Cr + PCr) (χ2(2) = 0.22, P

Matched MeSH terms: Dipeptides/metabolism*
Arginine glutamate improves healing of radiation-induced skin ulcers in guinea pigs

Khalin I, Kocherga G

Int J Radiat Biol, 2013 Dec;89(12):1108-15.
PMID: 23786463 DOI: 10.3109/09553002.2013.817698

The increase in the incidence of the radiation-induced skin injury cases and the absence of standard treatments escalate the interest in finding new and effective drugs for these lesions. We studied the effect of a 40% solution of arginine glutamate on the healing of radiation-induced skin ulcers in guinea pigs.

Matched MeSH terms: Dipeptides/therapeutic use*
In-vitro digestibility and amino acid composition of soy protein isolate cross-linked with microbial transglutaminase followed by heating with ribose

Gan CY, Cheng LH, Azahari B, Easa AM

Int J Food Sci Nutr, 2009;60 Suppl 7:99-108.
PMID: 19194813 DOI: 10.1080/09637480802635090

Cross-linked soy protein isolate (SPI) gels were produced via single-treatment of SPI with microbial transglutaminase (MTG) for 5 h or 24 h, or with ribose for 2 h, or via combined-treatments of SPI with MTG followed by heating with ribose. Assessment of gel strength and solubility concluded that measures which increased protein cross-links resulted in improved gel strength; however, in most cases the digestibility and amino acid content of the gels were reduced. The combined treated gel of SPI/MTG for 24 h/ribose was more easily digested by digestive enzymes and retained higher amounts of amino acids compared with the control Maillard gels of SPI with ribose. MTG consumed lysine and glutamine and reduced the availability of amino acids for the Maillard reaction with ribose. MTG was able to preserve the nutritional value of SPI against the destructive effect of the Maillard reaction and cross-links.

Matched MeSH terms: Dipeptides/metabolism
Fulltext Efficacy of metabolites of a Streptomyces strain (AS1) to control growth and mycotoxin production by Penicillium verrucosum, Fusarium verticillioides and Aspergillus fumigatus in culture

Danial AM, Medina A, Sulyok M, Magan N

Mycotoxin Res, 2020 May;36(2):225-234.
PMID: 31960351 DOI: 10.1007/s12550-020-00388-7

The objectives of this study were to determine the efficacy of metabolites of a Streptomyces strain AS1 on (a) spore germination, (b) mycelial growth, (c) control of mycotoxins produced by Penicillium verrucosum (ochratoxin A, OTA), Fusarium verticillioides (fumonisins, FUMs) and Aspergillus fumigatus (gliotoxin) and (d) identify the predominant metabolites involved in control. Initial screening showed that the Streptomyces AS1 strain was able to inhibit the mycelial growth of the three species at a distance, due to the release of secondary metabolites. A macroscopic screening system showed that the overall Index of Dominance against all three toxigenic fungi was inhibition at a distance. Subsequent studies showed that the metabolite mixture from the Streptomyces AS1 strain was very effective at inhibiting conidial germination of P. verrucosum, but less so against conidia of A. fumigatus and F. verticillioides. The efficacy was confirmed in studies on a conducive semi-solid YES medium in BioScreen C assays. Using the BioScreen C and the criteria of Time to Detection (TTD) at an OD = 0.1 showed good efficacy against P. verrucosum when treated with the Streptomyces AS1 extract at 0.95 and 0.99 water activity (aw) when compared to the other two species tested, indicating good efficacy. The effective dose for 50% control of growth (ED50) at 0.95 and 0.99 aw were approx. 0.005 ng/ml and 0.15 μg/ml, respectively, with the minimum inhibitory concentration (MIC) at both aw levels requiring > 40 μg/ml. In addition, OTA production was completely inhibited by 2.5 μg/ml AS1 extract at both aw levels in the in vitro assays. Ten metabolites were identified with four of these being predominant in concentrations > 2 μg/g dry weight biomass. These were identified as valinomycin, cyclo(L-Pro-L-Tyr), cyclo(L-Pro-L-Val) and brevianamide F.

Matched MeSH terms: Dipeptides/pharmacology
Fulltext Streptomyces sp. MUM212 as a Source of Antioxidants with Radical Scavenging and Metal Chelating Properties

Tan LT, Chan KG, Khan TM, Bukhari SI, Saokaew S, Duangjai A, et al.

Front Pharmacol, 2017;8:276.
PMID: 28567016 DOI: 10.3389/fphar.2017.00276

Reactive oxygen species and other radicals potentially cause oxidative damage to proteins, lipids, and DNA which may ultimately lead to various complications including mutations, carcinogenesis, neurodegeneration, cardiovascular disease, aging, and inflammatory disease. Recent reports demonstrate that Streptomyces bacteria produce metabolites with potent antioxidant activity that may be developed into therapeutic drugs to combat oxidative stress. This study shows that Streptomyces sp. MUM212 which was isolated from mangrove soil in Kuala Selangor, Malaysia, could be a potential source of antioxidants. Strain MUM212 was characterized and determined as belonging to the genus Streptomyces using 16S rRNA gene phylogenetic analysis. The MUM212 extract demonstrated significant antioxidant activity through DPPH, ABTS and superoxide radical scavenging assays and also metal-chelating activity of 22.03 ± 3.01%, 61.52 ± 3.13%, 37.47 ± 1.79%, and 41.98 ± 0.73% at 4 mg/mL, respectively. Moreover, MUM212 extract was demonstrated to inhibit lipid peroxidation up to 16.72 ± 2.64% at 4 mg/mL and restore survival of Vero cells from H2O2-induced oxidative damages. The antioxidant activities from the MUM212 extract correlated well with its total phenolic contents; and this in turn was in keeping with the gas chromatography-mass spectrometry analysis which revealed the presence of phenolic compounds that could be responsible for the antioxidant properties of the extract. Other chemical constituents detected included hydrocarbons, alcohols and cyclic dipeptides which may have contributed to the overall antioxidant capacity of MUM212 extract. As a whole, strain MUM212 seems to have potential as a promising source of novel molecules for future development of antioxidative therapeutic agents against oxidative stress-related diseases.

Matched MeSH terms: Dipeptides
Fulltext Thermodynamics of semi-specific ligand recognition: the binding of dipeptides to the E.coli dipeptide binding protein DppA

Zainol MKM, Linforth RJC, Winzor DJ, Scott DJ

Eur Biophys J, 2021 Dec;50(8):1103-1110.
PMID: 34611772 DOI: 10.1007/s00249-021-01572-y

This investigation of the temperature dependence of DppA interactions with a subset of three dipeptides (AA. AF and FA) by isothermal titration calorimetry has revealed the negative heat capacity ([Formula: see text]) that is a characteristic of hydrophobic interactions. The observation of enthalpy-entropy compensation is interpreted in terms of the increased structuring of water molecules trapped in a hydrophobic environment, the enthalpic energy gain from which is automatically countered by the entropy decrease associated with consequent loss of water structure flexibility. Specificity for dipeptides stems from appropriate spacing of designated DppA aspartate and arginine residues for electrostatic interaction with the terminal amino and carboxyl groups of a dipeptide, after which the binding pocket closes to become completely isolated from the aqueous environment. Any differences in chemical reactivity of the dipeptide sidechains are thereby modulated by their occurrence in a hydrophobic environment where changes in the structural state of entrapped water molecules give rise to the phenomenon of enthalpy-entropy compensation. The consequent minimization of differences in the value of ΔG0 for all DppA-dipeptide interactions thus provides thermodynamic insight into the biological role of DppA as a transporter of all dipeptides across the periplasmic membrane.

Matched MeSH terms: Dipeptides

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