Honeyfield D C, Carlson J R
Department of Animal Sciences, Washington State University, Pullman 99164-6320.
Appl Environ Microbiol. 1990 Mar;56(3):724-9. doi: 10.1128/aem.56.3.724-729.1990.
An assay to measure the rate of enzymatic formation of 3-methylindole (3MI) from indoleacetic acid (IAA) in Lactobacillus sp. strain 11201 was developed. The reaction mixture contained 50 micrograms of microbial protein per ml (range, 25 to 100 mg/ml), essential low-molecular-weight reaction ingredients, and radiolabeled IAA as substrate (range, 0 to 2 mM IAA). The reaction was anaerobic for 25 min at 39 degrees C. The apparent Michaelis-Menten constants were: Km, 0.14 mM IAA; and Vmax, 64 nmol 3MI.mg-1.min-1. The inhibitors avidin, aminopterin, and EDTA had no effect on the 3MI-forming enzyme. Dithionite stimulated the 3MI-forming enzyme. The product of the reaction, 3MI, acted as a noncompetitive inhibitor of the enzyme. Enzyme activity was associated with the cell wall fraction after sonication; treatment with the French press; or treatment with detergents, proteolytic enzymes, and EDTA.
开发了一种用于测定乳酸杆菌属菌株11201中吲哚乙酸（IAA）酶促形成3-甲基吲哚（3MI）速率的测定方法。反应混合物每毫升含有50微克微生物蛋白（范围为25至100毫克/毫升）、必需的低分子量反应成分以及作为底物的放射性标记IAA（范围为0至2毫摩尔/升IAA）。反应在39℃下厌氧进行25分钟。表观米氏常数为：Km，0.14毫摩尔/升IAA；Vmax，64纳摩尔3MI·毫克⁻¹·分钟⁻¹。抑制剂抗生物素蛋白、氨基蝶呤和乙二胺四乙酸（EDTA）对形成3MI的酶没有影响。连二亚硫酸盐刺激形成3MI的酶。反应产物3MI作为该酶的非竞争性抑制剂。酶活性与超声处理、法式压榨机处理或用去污剂、蛋白水解酶和EDTA处理后的细胞壁部分相关。
