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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 steroid 5αreductase activity in temporal lobe of human brain. Methods: 3H-labeled and unlabeled testosterone mixture as substrates for the enzyme, the establishment of steroid 5α-reductase enzyme-catalyzed assay. Results: 5αreductase existed in human brain temporal lobe tissue with two isozymes, and the optimal reaction pH was 7.0 (5αreductase 1) and 5.5 (5αreductase 2 ). The enzyme activities were 42.0 ± 11.2 pmol · h-1 · mg-1 protein (n = 9) and 26.2 ± 7.1 pmol · h-1 · mg-1 protein (n = 9), respectively. Mg2 + has an effect on both isozyme activities in temporal lobe tissue, and can improve enzyme reactivity. During the enzymatic reaction, both isoenzyme activities increase with the reaction time and the protein concentration in the sample. Conclusion: 5αreductase is distributed in human brain and exists in two isozymes. This result will provide a reliable methodological and theoretical basis for further study of 5α-reductase activity distribution, biochemical characteristics and physiological effects in human brain tissue.