骺板软骨中UDP-N-乙酰半乳糖胺的酶促形成。

Enzymatic formation of UDP-N-acetylgalactosamine in epiphysial-plate cartilage.

作者信息

De Luca G, Rindi S, Castellani A A

出版信息

Connect Tissue Res. 1978;6(2):83-8. doi: 10.3109/03008207809152615.

DOI:10.3109/03008207809152615

Abstract

The activity of UDP-N-acetylglucosamine 4'-epimerase (EC 5.1.3.7) from newborn pig epiphysial-plate cartilage was investigated. The formation of radioactive UDP-N-acetylgalactosamine from UDP-N-acetyl[U-14C]-glucosamine was demonstrated by radioautography, after hydrolysis of UDP-derivatives and separation of the hexosamines by paper chromatography. The pH optimum and the Km values for UDP-N-acetylglucosamine and NAD were determined. At equilibrium, the ratio UDP-N-acetylglucosamine/UDP-N-acetylgalactosamine reaches a value of about 2.3. The effect of UDP-xylose and UDP-glucuronic acid on the enzyme activity was investigated. NADH inhibits UDP-N-acetylglucosamine 4'-epimerase activity. The inhibitory effect of NADH seems to be strikingly correlated with the value of NAD/NADH ratio and pH.

摘要

对新生猪骺板软骨中的UDP-N-乙酰葡糖胺4'-表异构酶（EC 5.1.3.7）的活性进行了研究。在UDP衍生物水解并通过纸色谱法分离己糖胺后，通过放射自显影证明了由UDP-N-乙酰基[U-14C] -葡糖胺形成放射性UDP-N-乙酰半乳糖胺。测定了UDP-N-乙酰葡糖胺和NAD的最适pH值和Km值。在平衡时，UDP-N-乙酰葡糖胺/UDP-N-乙酰半乳糖胺的比值达到约2.3。研究了UDP-木糖和UDP-葡糖醛酸对酶活性的影响。NADH抑制UDP-N-乙酰葡糖胺4'-表异构酶的活性。NADH的抑制作用似乎与NAD/NADH比值和pH值显著相关。