A computational study of structural analysis of Class I human glucose-6-phosphate dehydrogenase (G6PD) variants: Elaborating the correlation to chronic non-spherocytic hemolytic anemia (CNSHA).

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common human enzyme defect that affects more than 500 million people worldwide. Individuals affected with G6PD deficiency may occasionally suffer mild-to-severe chronic hemolytic anemia. Chronic non-spherocytic hemolytic anemia (CNSHA) is a potential result of the Class I G6PD variants. This comparative computational study attempted to correct the defect in variants structure by docking the AG1 molecule to selected Class I G6PD variants [G6PDNashville (Arg393His), G6PDAlhambra (Val394Leu), and G6PDDurham (Lys238Arg)] at the dimer interface and structural NADP+ binding site. It was followed by an analysis of the enzyme conformations before and after binding to the AG1 molecule using the molecular dynamics simulation (MDS) approach, while the severity of CNSHA was determined via root-mean-square deviation (RMSD), root-mean-square fluctuation (RMSF), hydrogen bonds, salt bridges, radius of gyration (Rg), solvent accessible surface area analysis (SASA), and principal component analysis (PCA). The results revealed that G6PDNashville (Arg393His) and G6PDDurham (Lys238Arg) had lost the direct contact with structural NADP+ and salt bridges at Glu419 - Arg427 and Glu206 - Lys407 were disrupted in all selected variants. Furthermore, the AG1 molecule re-stabilized the enzyme structure by restoring the missing interactions. Bioinformatics approaches were also used to conduct a detailed structural analysis of the G6PD enzyme at a molecular level to understand the implications of these variants toward enzyme function. Our findings suggest that despite the lack of treatment for G6PDD to date, AG1 remains a novel molecule that promotes activation in a variety of G6PD variants.

The first mitochondrial genome data of an old world fruit bat, Cynopterus sphinx from Malaysia.

We assembled the complete mitogenome of Cynopterus sphinx (Vahl, 1797) of the family Pteropodidae originating from Malaysia. The total mitogenome size was 16,710bp which consists of 37 genes (13 protein-coding genes, 22 transfer RNA genes, two ribosomal RNA genes and one control region). A phylogenetic and BLASTn result showed the mitogenome sequence in this study varies by nearly 7% (93.48% similarity) from the same species in Cambodia. The next closest match of BLASTn was at 92% similarity to the C. brachyotis. This suggests the species-complex in Cynopterus sp. has given rise to the genetic variability.

Molecular Modeling and Simulation of Transketolase from Orthosiphon stamineus.

BACKGROUND: Orthosiphon stamineus is a traditional medicinal plant in Southeast Asia countries with various well-known pharmacological activities such as antidiabetic, diuretics and antitumor activities. Transketolase is one of the proteins identified in the leaves of the plant and transketolase is believed able to lower blood sugar level in human through non-pancreatic mechanism. In order to understand the protein behavioral properties, 3D model of transketolase and analysis of protein structure are of obvious interest. METHODS: In the present study, 3D model of transketolase was constructed and its atomic characteristics revealed. Besides, molecular dynamic simulation of the protein at 310 K and 368 K deciphered transketolase may be a thermophilic protein as the structure does not distort even at elevated temperature. This study also used the protein at 310 K and 368 K resimulated back at 310 K environment. RESULTS: The results revealed that the protein is stable at all condition which suggest that it has high capacity to adapt at different environment not only at high temperature but also from high temperature condition to low temperature where the structure remains unchanged while retaining protein function. CONCLUSION: The thermostability properties of transketolase is beneficial for pharmaceutical industries as most of the drug making processes are at high temperature condition.

An S188V mutation alters substrate specificity of non-stereospecific α-haloalkanoic acid dehalogenase E (DehE).

The non-stereospecific α-haloalkanoic acid dehalogenase E (DehE) degrades many halogenated compounds but is ineffective against ß-halogenated compounds such as 3-chloropropionic acid (3CP). Using molecular dynamics (MD) simulations and site-directed mutagenesis we show here that introducing the mutation S188V into DehE improves substrate specificity towards 3CP. MD simulations showed that residues W34, F37, and S188 of DehE were crucial for substrate binding. DehE showed strong binding ability for D-2-chloropropionic acid (D-2CP) and L-2-chloropropionic acid (L-2CP) but less affinity for 3CP. This reduced affinity was attributed to weak hydrogen bonding between 3CP and residue S188, as the carboxylate of 3CP forms rapidly interconverting hydrogen bonds with the backbone amide and side chain hydroxyl group of S188. By replacing S188 with a valine residue, we reduced the inter-molecular distance and stabilised bonding of the carboxylate of 3CP to hydrogens of the substrate-binding residues. Therefore, the S188V can act on 3CP, although its affinity is less strong than for D-2CP and L-2CP as assessed by Km. This successful alteration of DehE substrate specificity may promote the application of protein engineering strategies to other dehalogenases, thereby generating valuable tools for future bioremediation technologies.