title: Identification of a critical lysine residue at the active site in glyceraldehyde-3-phosphate dehydrogenase of Ehrlich ascites carcinoma cell. Comparison with the rabbit muscle enzyme.
abstract: The involvement of the lysine residue present at the active site of Ehrlich ascites carcinoma (EAC) cell glyceraldehyde-3-phosphate dehydrogenase (Gra3PDH) was investigated by using the lysine specific reagents trinitrobenzenesulfonic acid (TNBS) and pyridoxal phosphate (PP). Both TNBS and PP inactivated EAC cell Gra3PDH with pseudo-first-order kinetics with the rate dependent on modifier concentration. Kinetic analysis, including a Tsou plot, indicated that both TNBS and PP apparently react with one lysine residue per enzyme molecule. Two of the substrates, d-glyceraldehyde-3-phosphate and NAD, and also NADH, the product and competitive inhibitor, almost completely protected the enzyme from inactivation by TNBS. A comparative study of Gra3PDH of EAC cell and rabbit muscle indicates that the nature of active site of the enzyme is significantly different in these two cells. A double inhibition study using 5,5'-dithiobis(2-nitrobenzoic acid) and TNBS and subsequent reactivation of only the rabbit muscle enzyme by dithiothreitol suggested that a cysteine residue of this enzyme possibly reacts with TNBS. These studies on the other hand, confirm that an essential lysine residue is involved in the catalytic activity of the EAC cell enzyme. This difference in the nature of the active site of EAC cell Gra3PDH that may be related to the high glycolysis of malignant cells has been discussed.
authors.affiliation: Department of Biological Chemistry, Indian Association for the Cultivation of Science, Calcutta, India.
authors.forename: S
authors.initials: S
authors.lastname: Ghosh
authors.forename: K
authors.initials: K
authors.lastname: Mukherjee
authors.forename: M
authors.initials: M
authors.lastname: Ray
authors.forename: S
authors.initials: S
authors.lastname: Ray
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002286:Carcinoma, Ehrlich Tumor / Q000201:enzymology; D020134:Catalytic Domain; D004228:Dithionitrobenzoic Acid / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D024581:Glyceraldehyde-3-Phosphate Dehydrogenase (Phosphorylating) / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000235:genetics; D066298:In Vitro Techniques; D007700:Kinetics; D008239:Lysine / Q000737:chemistry; D051379:Mice; D008969:Molecular Sequence Data; D009132:Muscles / Q000201:enzymology; D021122:Protein Subunits; D011732:Pyridoxal Phosphate / Q000494:pharmacology; D011817:Rabbits; D014302:Trinitrobenzenesulfonic Acid / Q000494:pharmacology
chemical_list: D004791:Enzyme Inhibitors; D021122:Protein Subunits; D011732:Pyridoxal Phosphate; D014302:Trinitrobenzenesulfonic Acid; D004228:Dithionitrobenzoic Acid; D024581:Glyceraldehyde-3-Phosphate Dehydrogenase (Phosphorylating); D008239:Lysine