The Cleavage of Adenylosuccinate and 5-Amino-4-imidazole-N-succino-carboxamide Ribonucleotide by an Adenylosuccinate Lyase from Ehrlich Ascites Tumor Cells

Abstract

Adenylosuccinate lyase (EC 4.3.2.2), which catalyzes the conversion of either adenylosuccinate (AMPS) or 5-amino-4-imidazole-N-succino-carboxamide ribonucleotide (SAICAR) to fumarate and either AMP or 5-amino-4-imidazole carboxamide ribonucleotide (AICAR), was purified in excess of 80-fold by a one-step procedure involving column chromatography on phosphocellulose. The AMPS and SAICAR were prepared enzymatically from either AMP or AICAR. The Michaelis constants were 8.4 μM and 10.5 μM for AMPS and SAICAR, respectively. Product inhibition experiments were consistent with an ordered Uni Bi kinetic model with fumarate being the first product released.