人脑颞叶类固醇5α-还原酶活性的酶放射分析

Detection of steroid 5α reductase in human temporal lobe with radiometric method of enzyme assay

目的：对类固醇５α还原酶在人脑颞叶组织中的活性分布进行研究。方法：采用３Ｈ标记和未标记睾酮的混合液为酶作用底物，建立类固醇５α还原酶的酶放射分析法。结果：在人脑颞叶组织中５α还原酶以两种同工酶形式存在，其最适反应ｐＨ值分别为７．０（５α还原酶１）和５．５（５α还原酶２）；酶活性分别为４２．０±１１．２ｐｍｏｌ·ｈ－１·ｍｇ－１蛋白（ｎ＝９）和２６．２±７．１ｐｍｏｌ·ｈ－１·ｍｇ－１蛋白（ｎ＝９）。Ｍｇ２＋对颞叶组织中两种同工酶活性均有影响作用，能够提高酶的反应活性。在酶促反应过程中，随着反应时间和样品中蛋白质浓度的增加，两种同工酶活性升高。结论：在人脑组织中分布有５α还原酶且以两种同工酶形式存在。此结果将为进一步研究人脑组织中５α还原酶活性分布、生化特性及生理作用提供可靠的方法学和理论依据。

Objective:To study the distribution of 5α reductase in human temporal lobe.Methods:A mixture of 3H labelled and unlabelled testosterone were used as substrate for detection of steroid 5α reductase with radiometric method of enzyme assay.Results:Two isoenzymes of 5α reductase were found to be present in human temporal lobe with different pH optima(pH 7.0 for 5α reductase 1 and pH 5.5 for 5α reductase 2).MgCl 2 increased the activity of both two isoenzymes.The levels of two isoenzymes increased gradually with the increase in incubation time and increase in concentration of tissue protein.Conclusions:Results may serve as a reference in further studying the mechanism and method in examination of 5α reductase in human brain.