This chapter focuses on Imidazolonepropionic acid (Rat Liver). Imidazolonepropionic acid has an ultraviolet absorption peak at 260 mμ; this peak is not shown by the product of imidazolone propionic acid hydrolase activity, formiminoglutamic acid. Enzyme activity is assayed by following the decrease in absorption at 260 mμ. As imidazolonepropionic acid is very unstable at neutral pH under aerobic conditions, incubations must be performed anaerobically. The enzymatic degradation of imidazolonepropionic acid, as assayed by the disappearance of ultraviolet absorption at 260 mμ, is accompanied by the stoichiometric formation of formimino- glutamic acid as assayed by the method of Tabor and Wyngarden. When formiminoglutamic acid is incubated with the purified enzyme for extended periods under a variety of conditions, including anaerobiasis, no increase in ultraviolet absorbance at 260 mμ can be detected, indicating no formation of imidazolonepropionic acid. Imidazolonepropionic acid hydrolase has also been purified from Pseudomonas fluorescens.
ASJC Scopus subject areas
- Molecular Biology