Abstract

Quinolinate phosphoribosyltransferase was examined for susceptibility to different chemical modification reagents. Loss of enzyme activity with trinitrobenzenesulfonate (TNBS) occurred when 1.1 lysines per subunit were modified. Tryptic digestion of the modified enzyme followed by HPLC-MS analysis of the peptides showed Lys70 reacts with TNBS. Based on x-ray studies, this amino acid participates in A conformational change distant from the active site.

Keywords: Quinolinate phosphoribosyltransferase,, trinitrobenzene sulfonic acid modification, enzyme mechanism