Mutational analysis of cysteine 328 and cysteine 368 at the interface of Plasmodium falciparum adenylosuccinate synthetase

► P. falciparum (Pf) adenylosuccinate synthetase (AdSS) is a homodimeric enzyme. ► Dimer interface of PfAdSS is distinct from E. coli and mouse AdSS. ► Enzyme has a preponderance of positively charged residues at dimer interface. ► Crystal structure shows additional electron density around interface cysteines. ► Stability studies on interface cysteine mutants suggest role for thiolate anion.