产朊假丝酵母酶将尿酸转化为尿囊酸的立体特异性。

Stereospecificity of conversion of uric acid into allantoic acid by enzymes of Canadida utilis.

Okumura I, Kondo K, Miyake Y, Itaya K, Yamamoto T

J Biochem. 1976 May;79(5):1013-9. doi: 10.1093/oxfordjournals.jbchem.a131141.

Abstract

Allantoinase [EC 3.5.2.5] was isolated from cells of Candida utilis and unpurified by chromatography on columns of DEAE-cellulose and Sephadex G-200 after treatment with urea to remove urate oxidase [EC 1.7.3.3.]. 2. The purified allantoinase catalyzed the hydrolysis of allantoin into allantoic acid. However, only half of the allantoin produced from uric acid by urate oxidase was converted. The rest of the allantoin was unchanged, and showed a negative optical rotation. 3. On the other hand, the combined action of crude urate oxidase and allantoinase resulted in nearly complete conversion of uric acid into allantoic acid. Furthermore, the unpurified allantoinase preparation hydrolyzed racemic allantoin to allantoic acid completely. 4. These results indicate that the urate oxidase produces racemic allantoin from uric acid and that the allantoinase attacks only allantoin of positive optical rotation. The results also suggest that allantoin racemase is present in the yeast cells.

摘要

尿囊素酶[EC 3.5.2.5]从产朊假丝酵母细胞中分离得到，在用尿素处理以去除尿酸氧化酶[EC 1.7.3.3]后，通过DEAE - 纤维素柱和葡聚糖凝胶G - 200柱色谱进行粗纯化。2. 纯化后的尿囊素酶催化尿囊素水解为尿囊酸。然而，尿酸氧化酶由尿酸产生的尿囊素只有一半被转化。其余的尿囊素未发生变化，且旋光性为负。3. 另一方面，粗尿酸氧化酶和尿囊素酶共同作用可使尿酸几乎完全转化为尿囊酸。此外，未经纯化的尿囊素酶制剂可将外消旋尿囊素完全水解为尿囊酸。4. 这些结果表明，尿酸氧化酶从尿酸产生外消旋尿囊素，且尿囊素酶仅作用于旋光性为正的尿囊素。结果还表明，酵母细胞中存在尿囊素消旋酶。