Studies on kynurenine trans aminase ec 184.108.40.206 of carausius morosus and its significance in the morphological color change
Journal of Comparative Physiology B Metabolic and Transport Functions 111(1): 25-32
Kynurenine-transaminase (EC 220.127.116.11) was studied in the stick insect C. morosus. Enzyme activity was detected in Malphighian tubules and in fat body. The enzyme did not require supplementation by pyridoxal phosphate for activity. The Km for kynurenine was 0.5 .cntdot. 10-3 M. The enzyme was more active with oxaloacetic acid than with pyruvic or .alpha.-ketoglutaric acids. The optimum pH with oxaloacetic acid was 9.4-9.5. The enzyme extract converted 3-hydroxy-kynurenine to xanthurenic acid. Animals adapted at 18.degree. C had higher enzyme activity than animals adapted at 28.degree. C. Experimental increase of kynurenine level did not result in an increase of enzyme activity. Under in vitro conditions, the enzyme activity of whole animals produced .apprx. 200 times as much kynurenic acid as was excreted in the same time.