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Delineation of the intimate details of the backbone conformation of pyridine nucleotide coenzymes in aqueous solution

Bose KS, Sarma RH

Biochem Biophys Res Commun, 1975 Oct 27;66(4):1173-9.
PMID: 2
Matched MeSH terms: Models, Molecular
Fulltext Pathogenic nsSNPs that increase the risks of cancers among the Orang Asli and Malays

Khoruddin NA, Noorizhab MN, Teh LK, Mohd Yusof FZ, Salleh MZ

Sci Rep, 2021 Aug 09;11(1):16158.
PMID: 34373545 DOI: 10.1038/s41598-021-95618-y

Single-nucleotide polymorphisms (SNPs) are the most common genetic variations for various complex human diseases, including cancers. Genome-wide association studies (GWAS) have identified numerous SNPs that increase cancer risks, such as breast cancer, colorectal cancer, and leukemia. These SNPs were cataloged for scientific use. However, GWAS are often conducted on certain populations in which the Orang Asli and Malays were not included. Therefore, we have developed a bioinformatic pipeline to mine the whole-genome sequence databases of the Orang Asli and Malays to determine the presence of pathogenic SNPs that might increase the risks of cancers among them. Five different in silico tools, SIFT, PROVEAN, Poly-Phen-2, Condel, and PANTHER, were used to predict and assess the functional impacts of the SNPs. Out of the 80 cancer-related nsSNPs from the GWAS dataset, 52 nsSNPs were found among the Orang Asli and Malays. They were further analyzed using the bioinformatic pipeline to identify the pathogenic variants. Three nsSNPs; rs1126809 (TYR), rs10936600 (LRRC34), and rs757978 (FARP2), were found as the most damaging cancer pathogenic variants. These mutations alter the protein interface and change the allosteric sites of the respective proteins. As TYR, LRRC34, and FARP2 genes play important roles in numerous cellular processes such as cell proliferation, differentiation, growth, and cell survival; therefore, any impairment on the protein function could be involved in the development of cancer. rs1126809, rs10936600, and rs757978 are the important pathogenic variants that increase the risks of cancers among the Orang Asli and Malays. The roles and impacts of these variants in cancers will require further investigations using in vitro cancer models.

Matched MeSH terms: Models, Molecular
Unscrambling the effect of C-terminal tail deletion on the stability of a cold-adapted, organic solvent stable lipase from Staphylococcus epidermidis AT2

Kamarudin NH, Rahman RN, Ali MS, Leow TC, Basri M, Salleh AB

Mol Biotechnol, 2014 Aug;56(8):747-57.
PMID: 24771007 DOI: 10.1007/s12033-014-9753-1

Terminal moieties of most proteins are long known to be disordered and flexible. To unravel the functional role of these regions on the structural stability and biochemical properties of AT2 lipase, four C-terminal end residues, (Ile-Thr-Arg-Lys) which formed a flexible, short tail-like random-coil segment were targeted for mutation. Swapping of the tail-like region had resulted in an improved crystallizability and anti-aggregation property along with a slight shift of the thermostability profile. The lipolytic activity of mutant (M386) retained by 43 % compared to its wild-type with 18 % of the remaining activity at 45 °C. In silico analysis conducted at 25 and 45 °C was found to be in accordance to the experimental findings in which the RMSD values of M386 were more stable throughout the total trajectory in comparison to its wild-type. Terminal moieties were also observed to exhibit large movement and flexibility as denoted by high RMSF values at both dynamics. Variation in organic solvent stability property was detected in M386 where the lipolytic activity was stimulated in the presence of 25 % (v/v) of DMSO, isopropanol, and diethyl ether. This may be worth due to changes in the surface charge residues at the mutation point which probably involve in protein-solvent interaction.

Matched MeSH terms: Models, Molecular
Reductive alkylation of lipase: experimental and molecular modeling approaches

Rahman RN, Tejo BA, Basri M, Rahman MB, Khan F, Zain SM, et al.

Appl Biochem Biotechnol, 2004 8 12;118(1-3):11-20.
PMID: 15304735

Candida rugosa lipase was modified via reductive alkylation to increase its hydrophobicity to work better in organic solvents. The free amino group of lysines was alkylated using propionaldehyde with different degrees of modification obtained (49 and 86%). Far-ultraviolet circular dichroism (CD) spectroscopy of the lipase in aqueous solvent showed that such chemical modifications at the enzyme surface caused a loss in secondary and tertiary structure that is attributed to the enzyme unfolding. Using molecular modeling, we propose that in an aqueous environment the loss in protein structure of the modified lipase is owing to disruption of stabilizing salt bridges, particularly of surface lysines. Indeed, molecular modeling and simulation of a salt bridge formed by Lys-75 to Asp-79, in a nonpolar environment, suggests the adoption of a more flexible alkylated lysine that may explain higher lipase activity in organic solvents on alkylation.

Matched MeSH terms: Models, Molecular
Fulltext A new graph-based molecular descriptor using the canonical representation of the molecule

Hentabli H, Saeed F, Abdo A, Salim N

ScientificWorldJournal, 2014;2014:286974.
PMID: 25140330 DOI: 10.1155/2014/286974

Molecular similarity is a pervasive concept in drug design. The basic idea underlying molecular similarity is the similar property principle, which states that structurally similar molecules will exhibit similar physicochemical and biological properties. In this paper, a new graph-based molecular descriptor (GBMD) is introduced. The GBMD is a new method of obtaining a rough description of 2D molecular structure in textual form based on the canonical representations of the molecule outline shape and it allows rigorous structure specification using small and natural grammars. Simulated virtual screening experiments with the MDDR database show clearly the superiority of the graph-based descriptor compared to many standard descriptors (ALOGP, MACCS, EPFP4, CDKFP, PCFP, and SMILE) using the Tanimoto coefficient (TAN) and the basic local alignment search tool (BLAST) when searches were carried.

Matched MeSH terms: Models, Molecular*
Biochemical and structural characterization of meningococcal methylenetetrahydrofolate reductase

Pantong W, Pederick JL, Maenpuen S, Tinikul R, Jayapalan JJ, Jovcevski B, et al.

Protein Sci, 2023 Jun;32(6):e4654.
PMID: 37165541 DOI: 10.1002/pro.4654

Methylenetetrahydrofolate reductase (MTHFR) is a key metabolic enzyme in colonization and virulence of Neisseria meningitidis, a causative agent of meningococcal diseases. Here, the biochemical and structural properties of MTHFR from a virulent strain of N. meningitidis serogroup B (NmMTHFR) were characterized. Unlike other orthologs, NmMTHFR functions as a unique homohexamer, composed of three homo-dimerization partners, as shown in our 2.7 Å resolution crystal structure. Six active sites were formed solely within monomers and located away from the oligomerization interfaces. Flavin adenine dinucleotide cofactor formed hydrogen bonds with conserved sidechains, positioning its isoalloxazine ring adjacent to the overlapping binding sites of nicotinamide adenine dinucleotide (NADH) coenzyme and CH2 -H4 folate substrate. NmMTHFR utilized NADH (Km = 44 μM) as an electron donor in the NAD(P)H-CH2 -H4 folate oxidoreductase assay, but not nicotinamide adenine dinucleotide phosphate (NADPH) which is the donor required in human MTHFR. In silico analysis and mutagenesis studies highlighted the significant difference in orientation of helix α7A (Phe215-Thr225) with that in the human enzyme. The extended sidechain of Met221 on helix α7A plays a role in stabilizing the folded structure of NADH in the hydrophobic box. This supports the NADH specificity by restricting the phosphate group of NADPH that causes steric clashes with Glu26. The movement of Met221 sidechain allows the CH2 -H4 folate substrate to bind. The unique topology of its NADH and CH2 -H4 folate binding pockets makes NmMTHFR a promising drug target for the development of new antimicrobial agents that may possess reduced off-target side effects.

Matched MeSH terms: Models, Molecular
Quantum probability ranking principle for ligand-based virtual screening

Al-Dabbagh MM, Salim N, Himmat M, Ahmed A, Saeed F

J Comput Aided Mol Des, 2017 Apr;31(4):365-378.
PMID: 28220440 DOI: 10.1007/s10822-016-0003-4

Chemical libraries contain thousands of compounds that need screening, which increases the need for computational methods that can rank or prioritize compounds. The tools of virtual screening are widely exploited to enhance the cost effectiveness of lead drug discovery programs by ranking chemical compounds databases in decreasing probability of biological activity based upon probability ranking principle (PRP). In this paper, we developed a novel ranking approach for molecular compounds inspired by quantum mechanics, called quantum probability ranking principle (QPRP). The QPRP ranking criteria would make an attempt to draw an analogy between the physical experiment and molecular structure ranking process for 2D fingerprints in ligand based virtual screening (LBVS). The development of QPRP criteria in LBVS has employed the concepts of quantum at three different levels, firstly at representation level, this model makes an effort to develop a new framework of molecular representation by connecting the molecular compounds with mathematical quantum space. Secondly, estimate the similarity between chemical libraries and references based on quantum-based similarity searching method. Finally, rank the molecules using QPRP approach. Simulated virtual screening experiments with MDL drug data report (MDDR) data sets showed that QPRP outperformed the classical ranking principle (PRP) for molecular chemical compounds.

Matched MeSH terms: Models, Molecular
Fulltext Angiotensin Converting Enzyme (ACE)-Peptide Interactions: Inhibition Kinetics, In Silico Molecular Docking and Stability Study of Three Novel Peptides Generated from Palm Kernel Cake Proteins

Zarei M, Abidin NBZ, Auwal SM, Chay SY, Haiyee ZA, Sikin AM, et al.

Biomolecules, 2019 10 04;9(10).
PMID: 31590308 DOI: 10.3390/biom9100569

Three novel peptide sequences identified from palm kernel cake (PKC) generated protein hydrolysate including YLLLK, WAFS and GVQEGAGHYALL were used for stability study against angiotensin-converting enzyme (ACE), ACE-inhibition kinetics and molecular docking studies. Results showed that the peptides were degraded at different cleavage degrees of 94%, 67% and 97% for YLLLK, WAFS and GVQEGAGHYALL, respectively, after 3 h of incubation with ACE. YLLLK was found to be the least stable (decreased ACE-inhibitory activity) compared to WAFS and GVQEGAGHYALL (increased ACE-inhibitory activity). YLLLK showed the lowest Ki (1.51 mM) in inhibition kinetics study when compared to WAFS and GVQEGAGHYALL with Ki of 2 mM and 3.18 mM, respectively. In addition, ACE revealed the lowest Kmapp and Vmaxapp and higher catalytic efficiency (CE) in the presence of YLLLK at different concentrations, implying that the enzyme catalysis decreased and hence the inhibition mode increased. Furthermore, YLLLK showed the lowest docking score of -8.224 and seven interactions with tACE, while peptide GVQEGAGHYALL showed the higher docking score of -7.006 and five interactions with tACE.

Matched MeSH terms: Models, Molecular
An efficient ionic liquid mediated synthesis, cholinesterase inhibitory activity and molecular modeling study of novel piperidone embedded α,β-unsaturated ketones

Kia Y, Osman H, Kumar RS, Murugaiyah V, Basiri A, Khaw KY, et al.

Med Chem, 2014;10(5):512-20.
PMID: 24138113

A series of hitherto unreported piperidone embedded α,β-unsaturated ketones were synthesized efficiently in ionic solvent and evaluated for cholinesterase inhibitory activities against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes. Most of the synthesized compounds displayed good enzyme inhibition; therein compounds 7i and 7f displayed significant activity against AChE with IC50 values of 1.47 and 1.74 µM, respectively. Compound 6g showed the highest BChE inhibitory potency with IC50 value of 3.41 µM, being 5 times more potent than galanthamine. Molecular modeling simulation was performed using AChE and BChE receptors extracted from crystal structure of human AChE and human BChE to determine the amino acid residues involved in the binding interaction of synthesized compounds and their relevant receptors.

Matched MeSH terms: Models, Molecular*
Fulltext Synthesis, spectral characterization and crystals structure of some arsane derivatives of gold (I) complexes: a comparative density functional theory study

Shawkataly OB, Goh CP, Tariq A, Khan IA, Fun HK, Rosli MM

PLoS One, 2015;10(3):e0119620.
PMID: 25798915 DOI: 10.1371/journal.pone.0119620

A series of complexes of the type LAuCl where L = tris(p-tolylarsane), tris(m-tolylarsane), bis(diphenylarsano)ethane, and tris(naphthyl)arsane have been synthesized. All of the new complexes, 1-4, have been fully characterized by means of ¹H NMR and ¹³C NMR spectroscopy and single crystal X-ray crystallography. The structures of complexes 1-4 have been determined from X-ray diffraction data. The linear molecules have an average bond distance between gold-arsenic and gold-chlorine of 2.3390Å and 2.2846Å, respectively. Aurophilic interaction was prominent in complex 1 and 3, whereas complex 2 and 4 do not show any such interaction. The intermolecular gold interaction bond length was affected by the electronegativity of the molecule. The computed values calculated at DFT level using B3LYP function are in good agreement with the experimental results.

Matched MeSH terms: Models, Molecular
Fulltext Molecular phylogeny and predicted 3D structure of plant beta-D-N-acetylhexosaminidase

Hossain MA, Roslan HA

ScientificWorldJournal, 2014;2014:186029.
PMID: 25165734 DOI: 10.1155/2014/186029

beta-D-N-Acetylhexosaminidase, a family 20 glycosyl hydrolase, catalyzes the removal of β-1,4-linked N-acetylhexosamine residues from oligosaccharides and their conjugates. We constructed phylogenetic tree of β-hexosaminidases to analyze the evolutionary history and predicted functions of plant hexosaminidases. Phylogenetic analysis reveals the complex history of evolution of plant β-hexosaminidase that can be described by gene duplication events. The 3D structure of tomato β-hexosaminidase (β-Hex-Sl) was predicted by homology modeling using 1now as a template. Structural conformity studies of the best fit model showed that more than 98% of the residues lie inside the favoured and allowed regions where only 0.9% lie in the unfavourable region. Predicted 3D structure contains 531 amino acids residues with glycosyl hydrolase20b domain-I and glycosyl hydrolase20 superfamily domain-II including the (β/α)8 barrel in the central part. The α and β contents of the modeled structure were found to be 33.3% and 12.2%, respectively. Eleven amino acids were found to be involved in ligand-binding site; Asp(330) and Glu(331) could play important roles in enzyme-catalyzed reactions. The predicted model provides a structural framework that can act as a guide to develop a hypothesis for β-Hex-Sl mutagenesis experiments for exploring the functions of this class of enzymes in plant kingdom.

Matched MeSH terms: Models, Molecular*
Multitarget drug design strategy in Alzheimer's disease: focus on cholinergic transmission and amyloid-β aggregation

Simoni E, Bartolini M, Abu IF, Blockley A, Gotti C, Bottegoni G, et al.

Future Med Chem, 2017 06;9(10):953-963.
PMID: 28632446 DOI: 10.4155/fmc-2017-0039

AIM: Alzheimer pathogenesis has been associated with a network of processes working simultaneously and synergistically. Over time, much interest has been focused on cholinergic transmission and its mutual interconnections with other active players of the disease. Besides the cholinesterase mainstay, the multifaceted interplay between nicotinic receptors and amyloid is actually considered to have a central role in neuroprotection. Thus, the multitarget drug-design strategy has emerged as a chance to face the disease network.
METHODS: By exploiting the multitarget approach, hybrid compounds have been synthesized and studied in vitro and in silico toward selected targets of the cholinergic and amyloidogenic pathways.
RESULTS: The new molecules were able to target the cholinergic system, by joining direct nicotinic receptor stimulation to acetylcholinesterase inhibition, and to inhibit amyloid-β aggregation.
CONCLUSION: The compounds emerged as a suitable starting point for a further optimization process.

Matched MeSH terms: Models, Molecular
A combination of evolutionary trace method, molecular surface accessibility and hydrophobicity analysis to design a high hydrophobicity laccase

Mohamad SB, Ong AL, Khairuddin RF, Ripen AM

In Silico Biol. (Gedrukt), 2010;10(3):145-53.
PMID: 22430288 DOI: 10.3233/ISB-2010-0423

Laccases are industrially attractive enzymes and their applications have expanded to the field of bioremediation. The challenge of today's biotechnology in enzymatic studies is to design enzymes that not only have a higher activity but are also more stable and could fit well with the condition requirements. Laccases are known to oxidize non-natural substrates like polycyclic aromatic hydrocarbons (PAHs). We suppose by increasing the hydrophobicity of laccase, it would increase the chance of the enzyme to meet the hydrophobic substrates in a contamination site, therefore increasing the bioremediation efficacy of PAHs from environment. In this attempt, the applications of evolutionary trace (ET), molecular surface accessibility and hydrophobicity analysis on laccase sequences and laccase's crystal structure (1KYA) are described for optimal design of an enzyme with higher hydrophobicity. Our analysis revealed that Q23A, Q45I, N141A, Q237V, N262L, N301V, N331A, Q360L and Q482A could be promising exchanges to be tested in mutagenesis experiments.

Matched MeSH terms: Models, Molecular
Fulltext The structure of a major surface antigen SAG19 from Eimeria tenella unifies the Eimeria SAG family

Ramly NZ, Dix SR, Ruzheinikov SN, Sedelnikova SE, Baker PJ, Chow YP, et al.

Commun Biol, 2021 03 19;4(1):376.
PMID: 33742128 DOI: 10.1038/s42003-021-01904-w

In infections by apicomplexan parasites including Plasmodium, Toxoplasma gondii, and Eimeria, host interactions are mediated by proteins including families of membrane-anchored cysteine-rich surface antigens (SAGs) and SAG-related sequences (SRS). Eimeria tenella causes caecal coccidiosis in chickens and has a SAG family with over 80 members making up 1% of the proteome. We have solved the structure of a representative E. tenella SAG, EtSAG19, revealing that, despite a low level of sequence similarity, the entire Eimeria SAG family is unified by its three-layer αβα fold which is related to that of the CAP superfamily. Furthermore, sequence comparisons show that the Eimeria SAG fold is conserved in surface antigens of the human coccidial parasite Cyclospora cayetanensis but this fold is unrelated to that of the SAGs/SRS proteins expressed in other apicomplexans including Plasmodium species and the cyst-forming coccidia Toxoplasma gondii, Neospora caninum and Besnoitia besnoiti. However, despite having very different structures, Consurf analysis showed that Eimeria SAG and Toxoplasma SRS families each exhibit marked hotspots of sequence hypervariability that map to their surfaces distal to the membrane anchor. This suggests that the primary and convergent purpose of the different structures is to provide a platform onto which sequence variability can be imposed.

Matched MeSH terms: Models, Molecular
Synthesis, crystal structures and characterization of late first row transition metal complexes derived from benzothiazole core: anti-tuberculosis activity and special emphasis on DNA binding and cleavage property

Netalkar PP, Netalkar SP, Budagumpi S, Revankar VK

Eur J Med Chem, 2014 May 22;79:47-56.
PMID: 24721314 DOI: 10.1016/j.ejmech.2014.03.083

Air and moisture stable coordination compounds of late first row transition metals, viz. Co(II), Ni(II), Cu(II) and Zn(II), with a newly designed ligand, 2-(2-benzo[d]thiazol-2-yl)hydrazono)propan-1-ol (LH), were prepared and successfully characterized using various spectro-analytical techniques. The molecular structures of the ligand and nickel complex were unambiguously determined by single-crystal X-ray diffraction method. The [Ni(LH)2]Cl2.3H2O complex is stabilized by intermolecular CH⋯π stacking interactions between the methyl hydrogen and the C18 atom of the phenyl ring (C11-H11B⋯C18) forming 1D zig-zag chain structure. Both, the ligand and its copper complex, were electrochemically active in the working potential range, showing quasi-reversible redox system. The interactions of all the compounds with calf thymus DNA have been comprehensively investigated using electronic absorption spectroscopy, viscosity, electrochemistry and thermal denaturation studies. The cleavage reaction on pBR322 DNA has been monitored by agarose gel electrophoresis. The results showed that the ligand can bind to CT-DNA through partial intercalation, whereas the complexes bind electrostatically. Further, [Ni(LH)2]Cl2.3H2O and [CuLCl(H2O)2] complexes in the series have high binding and cleavage affinity towards pBR322 DNA. Additionally, all the compounds were screened for anti-tuberculosis activity. All the complexes revealed an MIC value of 0.8 μg/mL, which is almost 8 times active than standard used (Streptomycin, 6.25 μg/mL).

Matched MeSH terms: Models, Molecular
A facile chemo-, regio- and stereoselective synthesis and cholinesterase inhibitory activity of spirooxindole-pyrrolizine-piperidine hybrids

Kia Y, Osman H, Kumar RS, Murugaiyah V, Basiri A, Perumal S, et al.

Bioorg Med Chem Lett, 2013 May 15;23(10):2979-83.
PMID: 23570788 DOI: 10.1016/j.bmcl.2013.03.027

A series of novel hybrid spiro heterocycles comprising pyrrolizine, spiroxindole and piperidine moieties was synthesized chemo-, regio- and stereoselectively in good yields from 1,3-dipolar cycloaddition reaction of a series of 1-acryloyl-3,5-bisarylmethylidenepiperidin-4-ones with azomethine ylides generated in situ from 5-choloroisatin and l-proline in methanol. These cycloadducts displayed significant cholinesterase inhibitory activity. Among the compounds screened, 8g and 8e, showed maximum inhibitory activity against acetylcholinesterase (AChE) and butyrylcholinestrase (BChE) with IC50 values of 3.33 and 3.13μM, respectively.

Matched MeSH terms: Models, Molecular
Selective binding of imidazolium cations in building multi-component layers

Ling I, Alias Y, Sobolev AN, Byrne LT, Raston CL

Chemistry, 2010 Jun 18;16(23):6973-82.
PMID: 20455217 DOI: 10.1002/chem.200903320

Addition of 1-alkyl-3-methylimidazolium (C(n)-mim) cations 3-5 to a mixture of bis-phosphonium cation 2 and sodium p-sulfonatocalix[4]arene (1) in the presence of lanthanide ions results in the selective binding of an imidazolium cation into the cavity of the calixarene. The result is a multi-layered solid material with an inherently flexible interplay of the components. Incorporating ethyl-, n-butyl- or n-hexyl-mim cations into the multi-layers results in significant perturbation of the structure, the most striking effect is the tilting of the plane of the bowl-shaped calixarene relative to the plane of the multi-layer, with tilt angles of 7.2, 28.9 and 65.5 degrees , respectively. The lanthanide ions facilitate complexation, but are not incorporated into the structures and, in all cases, the calixarene takes on a 5- charge, with one of the lower-rim phenolic groups deprotonated. ROESY NMR experiments and other (1)H NMR spectroscopy studies establish the formation of 1:1 supermolecules of C(n)-mim and calixarene, regardless of the ratio of the two components, and indicate that the supermolecules undergo rapid exchange on the NMR spectroscopy timescale.

Matched MeSH terms: Models, Molecular
Crystal structures of Nipah and Hendra virus fusion core proteins

Lou Z, Xu Y, Xiang K, Su N, Qin L, Li X, et al.

FEBS J, 2006 Oct;273(19):4538-47.
PMID: 16972940

The Nipah and Hendra viruses are highly pathogenic paramyxoviruses that recently emerged from flying foxes to cause serious disease outbreaks in humans and livestock in Australia, Malaysia, Singapore and Bangladesh. Their unique genetic constitution, high virulence and wide host range set them apart from other paramyxoviruses. These characteristics have led to their classification into the new genus Henpavirus within the family Paramyxoviridae and to their designation as Biosafety Level 4 pathogens. The fusion protein, an enveloped glycoprotein essential for viral entry, belongs to the family of class I fusion proteins and is characterized by the presence of two heptad repeat (HR) regions, HR1 and HR2. These two regions associate to form a fusion-active hairpin conformation that juxtaposes the viral and cellular membranes to facilitate membrane fusion and enable subsequent viral entry. The Hendra and Nipah virus fusion core proteins were crystallized and their structures determined to 2.2 A resolution. The Nipah and Hendra fusion core structures are six-helix bundles with three HR2 helices packed against the hydrophobic grooves on the surface of a central coiled coil formed by three parallel HR1 helices in an oblique antiparallel manner. Because of the high level of conservation in core regions, it is proposed that the Nipah and Hendra virus fusion cores can provide a model for membrane fusion in all paramyxoviruses. The relatively deep grooves on the surface of the central coiled coil represent a good target site for drug discovery strategies aimed at inhibiting viral entry by blocking hairpin formation.

Matched MeSH terms: Models, Molecular
Fulltext Rheological studies of PMMA-PVC based polymer blend electrolytes with LiTFSI as doping salt

Liew CW, Durairaj R, Ramesh S

PLoS One, 2014;9(7):e102815.
PMID: 25051241 DOI: 10.1371/journal.pone.0102815

In this research, two systems are studied. In the first system, the ratio of poly (methyl methacrylate) (PMMA) and poly (vinyl chloride) (PVC) is varied, whereas in the second system, the composition of PMMA-PVC polymer blends is varied with dopant salt, lithium bis (trifluoromethanesulfonyl) imide (LiTFSI) with a fixed ratio of 70 wt% of PMMA to 30 wt% of PVC. Oscillation tests such as amplitude sweep and frequency sweep are discussed in order to study the viscoelastic properties of samples. Elastic properties are much higher than viscous properties within the range in the amplitude sweep and oscillatory shear sweep studies. The crossover of G' and G'' is absent. Linear viscoelastic (LVE) range was further determined in order to perform the frequency sweep. However, the absence of viscous behavior in the frequency sweep indicates the solid-like characteristic within the frequency regime. The viscosity of all samples is found to decrease as shear rate increases.

Matched MeSH terms: Models, Molecular
Fulltext Synthesis, Biological Evaluation and Molecular Docking Studies of 6-Aryl-2-Styrylquinazolin-4(3H)-Ones

Agbo EN, Makhafola TJ, Choong YS, Mphahlele MJ, Ramasami P

Molecules, 2015 Dec 25;21(1):E28.
PMID: 26712730 DOI: 10.3390/molecules21010028

Suzuki-Miyaura cross-coupling of 6-bromo-2-styrylquinazolin-4(3H)-ones with arylboronic acids afforded a series of novel 6-aryl-2-styrylquinazolin-4(3H)-ones. These compounds were evaluated for potential anticancer properties against the human renal (TK-10), melanoma (UACC-62) and breast cancer (MCF-7) cell lines. Their antimicrobial properties were also evaluated against six Gram-positive and four Gram-negative bacteria, as well as two strains of fungi. Molecular docking studies (in silico) were conducted on compounds 5a, b, d and 6a, b, d-f to recognize the hypothetical binding motif of the title compounds within the active site of the dihydrofolate reductase and thymidylate synthase enzymes.

Matched MeSH terms: Models, Molecular

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