No metal cofactor in orotidine 5 '-monophosphate decarboxylase

Orotidine 5'-monophosphate decarboxylase (OMP decarboxylase, ODCase) is an important enzyme that catalyzes the final step of de novo pyrimidine nucleo tide biosynthesis. The mechanism of this unique enzyme and whether metal io ns play any role in catalysis have been topics of intense research interest . In this report, the role of Zn in ODCase was reexamined. Atomic absorptio n (AA) and X-ray absorption (XAS) spectroscopic studies did not detect zinc in active enzyme samples at high concentration. The XAS results also indic ated the absence of other transition metal ions in ODCase. (C) 1999 Academi c Press.