title: Catalysis by N-acetyl-D-glucosaminylphosphatidylinositol de-N-acetylase (PIG-L) from Entamoeba histolytica: new roles for conserved residues.
abstract: We showed previously that Entamoeba histolytica PIG-L exhibits a novel metal-independent albeit metal-stimulated activity. Using mutational and biochemical analysis, here we identify Asp-46 and His-140 of the enzyme as being important for catalysis. We show that these mutations neither affect the global conformational of the enzyme nor alter its metal binding affinity. The defect in catalysis, due to the mutations, is specifically due to an effect on V(max) and not due to altered substrate affinity (or K(m)). We propose a general acid-base pair mechanism to explain our results.
authors: School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
authors: Mohammad
authors: M
authors: Ashraf
authors: School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
authors: Perinthottathil
authors: P
authors: Sreejith
authors: School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
authors: Usha
authors: U
authors: Yadav
authors: School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India. Electronic address: sskomath@mail.jnu.ac.in.
authors: Sneha Sudha
authors: SS
authors: Komath
mesh_terms: D000581:Amidohydrolases / Q000737:chemistry* / Q000502:physiology; D002384:Catalysis; D002942:Circular Dichroism; D004748:Entamoeba histolytica / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D054794:Glycomics / Q000379:methods; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008670:Metals / Q000737:chemistry; D008954:Models, Biological; D008956:Models, Chemical; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D011487:Protein Conformation; D017434:Protein Structure, Tertiary
chemical_list: D008670:Metals; D000581:Amidohydrolases; C087696:N-acetylglucosaminyl-phosphatidylinositol de-N-acetylase