Creatinine iminohydrolase free from urease activity, methods of preparation and use, and assay compositions and analytical elements containing same.

摘要

A urease-free creatinine iminohydrolase enzyme composition is obtained from an aerobic soil microorganism. The enzyme preferably has a molecular weight of from 250,000 to 300,000; a maximum activity at a pH between 7 and 8 as measured at 37°C; a Km of 3 to 5 mM for creatinine as measured at 37°C, pH 7.5; and a specific activity for creatinine of at least 1.0 unit per milligram of protein in the composition as measured at 37°C, pH 7.5. The preferred enzyme composition is derived from the aerobic soil microorganism ATCC 31,546. Assay methods, compositions, and elements containing the urease-free creatinine iminohydrolase for the determination of creatinine in an aqueous liquid are also disclosed.