CATALYTIC ROLES OF LYSINES (K9, K27, K31) IN THE N-TERMINAL DOMAIN INHUMAN ADENYLATE KINASE BY RANDOM SITE-DIRECTED MUTAGENESIS

To elucidate lysine residues in the N-terminal domain of human cytosol ic adenylate kinase (hAK1, EC 2.7.4.3), random site-directed mutagenes is of K9, K27, and K31 residues was performed, and six mutants were an alyzed by steady-state kinetics. K9 residue may play an important role in catalysis by interacting with AMP(2-). K27 and K31 residues appear to play a functional role in catalysis by interacting with MgATP(2-). In human AK, the epsilon-amino group in the side chain of these lysin e residues would be essential for phosphoryl transfer between MgATP(2- ) and AMP(2-) during transition state.