Abdul Hai

A Structured-based Model for the Decreased Activity of Ala222Val and Glu429Ala Methylenetetrahydrofolate Reductase (MTHFR) Mutants

The structure of human Methylenetetrahydrofolate Reductase (MTHFR) is not known either by NMR or by X-ray methods. Phosphorylation seems to play an important role in the functioning of this flavoprotein. MTHFR catalyzes an irreversible reaction in homocysteine metabolism. Phosphorylation decreases the activity of MTHFR by enhancing the sensitivity of the enzyme to SAdenosylmethione. Two common polymorphisms in MTHFR, Ala222Val and Glu429Ala, can result in a number of vascular diseases. Effects of the Glu429Ala polymorphism on the structure of human MTHFR remain undetermined due to limited structural information. Hence, structural models of the MTHFR mutants were constructed using I-TASSER and assessed by PROCHECK, DFIRE and Verify3D tools. A mechanism is further suggested for the decreased activity of the Ala222Val and Glu429Ala mutants due to a decrease in number of serine phosphorylation sites using information gleaned from the molecular models. This provides insights for the understanding of structure-function relationship for MTHFR.

Differences in structural elements of Bcr-Abl oncoprotein isoforms in Chronic Myelogenous Leukemia

in silico modeling, using Psipred and ExPASy servers was employed to determine the structural elements of Bcr-Abl oncoprotein (p210BCR-ABL) isoforms, b2a2 and b3a2, expressed in Chronic Myelogenous Leukemia (CML). Both these proteins are tyrosine kinases having masses of 210-kDa and differing only by 25 amino acids coded by the b3 exonand an amino acidsubstitution (Glu903Asp). The secondary structure elements of the two proteins show differences in five α-helices and nine β-strands which relates to differences in the SH3, SH2, SH1 and DNA-binding domains. These differences can result in different roles played by the two isoforms in mediating signal transduction during the course of CML.

α2-µ-Globulin fragment (a2-f) from kidneys of male rats

The structure of α2-µ-Globulin fragment (A2-f) is not known.α2-µ-Globulin fragment (A2-f) is a 15.5 kDa protein that binds equimolar amount of fatty acids in male rat kidneys. The expression of this protein has been shown to change in response to druginduced and genetic hypertension which suggests that it plays an important role in renal fatty acid metabolism under pathological conditions as well as normal conditions. A2-f has sequence homology with amino acid 28-178 of α2-µ-Globulin (A2U) that is synthesized pre-dominantly in the male rat liver and is present in the urine. It is believed that unusual structural features permit A2-f to be targeted to the proximal tubule cell; to escape lysosomal degradation in liver and to enter the cytosol of proximal tubule cells of the kidneys. Homology modeling has been employed to determine the structural elements of this protein and they have been compared with the published structure of A2U. Results suggest differences between the structure of A2-f and its precursor protein A2U.

Porphyrin derivatives as inhibitors for acetylcholinesterase from Drosophila melanogaster

The cure for Alzheimers disease (AD) is still unknown. According to Cholinergic hypothesis, Alzheimers disease is caused by the reduced synthesis of the neurotransmitter, Acetylcholine. Regional cerebral blood flow can be increased in patients with Alzheimers disease by Acetylcholinesterase (AChE) inhibitors. In this regard, Tetraphenylporphinesulfonate (TPPS), 5,10,15,20- Tetrakis (4-sulfonatophenyl) porphyrinato Iron(III) Chloride (FeTPPS) and 5,10,15,20-Tetrakis (4-sulfonatophenyl) porphyrinatoIron(III) nitrosyl Chloride (FeNOTPPS) were investigated as candidate compounds for inhibition of Acteylcholinesterase of Drosophila melanogaster (DmAChE) by use of Molecular Docking. The results show that FeNOTPPS forms the most stable complex with DmAChE.

Increase in activity of Na+, K+-ATPase by Porphyrin compounds as treatment for Dysnatremias caused by Diabetes Mellitus

Objective: The aim of this study was to test the action of Porphyrin compounds, Tetraphenylporphine sulfonate (TPPS), 5,10,15,20-Tetrakis (4-sulfonatophenyl) porphyrinato Iron(III) Chloride (FeTPPS) and 5,10,15,20-Tetrakis (4-sulfonatophenyl) porphyrinato Iron(III) nitrosyl Chloride (FeNOTPPS), on Na+, K+ -ATPase of cell membrane of erythrocytes. Methods: Enzymatic assays, measuring the amount of inorganic phosphate produced, were used to estimate the activity of Na+, K+-ATPase. Results: The results show that Porphyrin compounds exert an insulin-like effect on Na+, K+-ATPase. They act by increasing the activity of the membrane-bound enzyme. Conclusion: All the three Porphyrin compounds increased the activity of erythrocyte Na+, K+-ATPase. The exact mechanism of action of these compounds is not clear.

Indirect Evidence for Self Association of Muscle Fatty Acid Binding Protein from Locusta migratoria

Fatty acid binding proteins are involved in the storage and transport of long chain fatty acids. This study about the muscle fatty acid binding protein of Locusta migratoria (LM-FABP) was pursued by the use of far-UV Circular Dichroism (CD) spectroscopy. It provides indirect evidence that the protein self-associates in solution. A hydrophobic patch on the surface of LM-FABP, reported earlier, can mediate self-association between the protein monomers. The property of self-association can also affect the activity of membrane-bound enzymes in locusts such as Adenine Nucleotide Translocase (also known as the ADP/ATP translocator) which is fatty acid or acyl coenzymeA dependent. proteins. The self-association or aggregation of proteins results in the development of such diseases as Downs syndrome, Alzheimers disease (7), cataracts (8), (9) and many others. The formation of inclusion bodies is a major problem in the overexpression of recombinant proteins (10)-(13), while the production and in vivo delivery of protein drugs is often complicated by association (14). Adenine Nucleotide Translocase (ANT) is an integral protein of the inner mitochondrial membrane that plays an important role in cellular bioenergetics (15), apoptosis (16) and cell signaling (17). ANT catalyzes the exchange of ADP for ATP across the inner mitochondrial membrane thereby coupling oxidative phosphorylation to cell metabolism. The property of self-association of muscle FABP of Locusta migratoria was investigated by Circular Dichroism (CD) spectroscopy. Self-association of LM-FABP can produce an effect on the activity of membrane-bound enzymes in insects such as Adenine Nucleotide Translocase (also known as the ADP/ATP translocator) which is fatty acid or acyl coenzymeA dependent.

Novel Chimeric Protein as Therapeutic Vaccine against Hepatitis B Virus

A significant percentage of the human population does not respond well to commercially available recombinant Hepatitis B Virus (HBV) surface vaccine. So it must be replaced by modified vaccines. A chimeric protein comprising both the core and surface portions of the viral envelope was designed on the premise that if the HBV surface protein is fused with the core protein of the viral envelope, it can produce B-cell as well as T-cell immune response. A 23 kDa molecular weight protein, comprising 216 amino acids and consisting of the core and surface regions of the viral envelope protein, was designed. NNPREDICT and PSIPRED programs have provided the secondary structure elements of the protein. The tertiary structure of the protein was predicted by the use of 3D-JIGSAW program. In the predicted tertiary structure, α-helices form a helical bundle domain and the β-strands form another separate domain.

Model of β-Sheet of Muscle Fatty Acid Binding Protein of Locusta migratoria Displays Characteristic Topology.

The β-sheet of muscle fatty acid binding protein of Locusta migratoria (Lm-FABP) was modeled by employing 2-D NMR data and the Rigid Body Assembly method. The model shows the β-sheet to comprise ten β-strands arranged anti-parallel to each other. There is a β-bulge between Ser 13 and Gln 14 which is a difference from the published structure of β-sheet of bovine heart Fatty Acid Binding Protein. Also, a hydrophobic patch consisting of Ile 45, Phe 51, Phe 64 and Phe 66 is present on the surface which is characteristic of most Fatty Acid Binding Proteins. A “gap” is present between βD and βE that provides evidence for the presence of a portal or opening between the polypeptide chains which allows ligand fatty acids to enter the protein cavity and bind to the protein.

Binding interactions of porphyrin derivatives with Ca 2+ ATPase of sarcoplasmic reticulum (SERCA1a)

The use of Porphyrin derivatives as photosensitizers in Photodynamic Therapy (PDT) was investigated by means of a molecular docking study. These molecules can bind to intracellular targets such as P-type CaCa2+ ATPase of sarcoplasmic reticulum (SERCA1a). CAChe software was successfully employed for conducting the docking of Tetraphenylporphinesulfonate(TPPS), 5,10,15,20- Tetrakis (4-sulfonatophenyl) porphyrinato Iron(III) Chloride (FeTPPS) and 5,10,15,20-Tetrakis (4-sulfonatophenyl) porphyrinato Iron(III) nitrosyl Chloride (FeNOTPPS) with CaCa2+ ATPase from sarcoplasmic reticulum of rabbit. The results show that FeNOTPPS forms the most stable complex with CaCa2+ ATPase.

Insight from γC1 protein model for implication in cotton leaf curl disease

DNA γ is approximately half of the size of Begomovirus DNA. It encodes a γC1 gene that is conserved in position and size. This gene has the capacity to encode a 13 to 14 kDa protein comprising 118 amino acid residues. It has been shown earlier that γC1 protein is necessary for inducing symptoms of cotton leaf curl disease. The structure for γC1 (CLCuDγ01-Pakistan) is still unknown. Therefore, a model of γC1 (CLCuDγ01-Pakistan) was developed using DoBo and I-TASSER servers followed by validation by PROCHECK and VERIFY 3D servers. The developed model provides an insight in a role for this multifunctional protein in causing Cotton Leaf Curl Disease (CLCuD). A possible function of this protein might be the suppression of RNAsilencing in cotton plants.