passages.id: split_5_test_3429_passage
passages.type: progene_text
passages.text: We determined the putative zinc binding residues ( His324 , His328 , and Glu347 ) and the essential Glu325 residue for the enzyme using site - directed mutagenesis ( Fukasawa , K. M. , et al. ( 1999 ) Biochem. J. 339 , 497 - 502 ) .