Shinki T, Suda T
Department of Biochemistry, School of Dentistry, Showa University, Tokyo, Japan.
Eur J Biochem. 1989 Aug 1;183(2):285-90. doi: 10.1111/j.1432-1033.1989.tb14926.x.
We have reported that spermidine N1-acetyltransferase has a larger role than ornithine decarboxylase in putrescine synthesis in chick duodenum induced by 1 alpha,25-dihydroxycholecalciferol (calcitriol) [Shinki, T., Kadofuku, T., Sato, T. and Suda, T. (1986) J. Biol. Chem. 261, 11712-11716]. In the present study, spermidine N1-acetyltransferase was purified from the duodenal cytosol of calcitriol-treated chicks to homogeneity judged by SDS/polyacrylamide gel electrophoresis. The purified enzyme converted spermidine only to N1-acetyl-spermidine. The apparent molecular mass of the purified spermidine N1-acetyltransferase was found to be 36 kDa by gel filtration on Sephacryl S-200 and 18 kDa by SDS/polyacrylamide gel electrophoresis. When duodenal crude 105,000 x g extracts were directly applied to a Sephacryl S-200 column without prior purification, three peaks with spermidine N1-acetyltransferase activity appeared. The first peak was in the void volume, the second peak was in the fraction corresponding to an apparent molecular mass of 70 kDa, and the third peak was in the fraction corresponding to 36 kDa. These results suggest that spermidine N1-acetyltransferase exists as a dimer of the 18 kDa subunits and is stabilized in (a) form(s) bound to other components or proteins in intact cells.
我们已经报道，在1α,25-二羟基胆钙化醇（骨化三醇）诱导的雏鸡十二指肠腐胺合成过程中，亚精胺N1-乙酰基转移酶比鸟氨酸脱羧酶发挥着更大的作用[Shinki, T., Kadofuku, T., Sato, T. 和 Suda, T. (1986) J. Biol. Chem. 261, 11712 - 11716]。在本研究中，通过SDS/聚丙烯酰胺凝胶电泳判断，从经骨化三醇处理的雏鸡十二指肠胞质溶胶中纯化得到了均一的亚精胺N1-乙酰基转移酶。纯化后的酶仅将亚精胺转化为N1-乙酰基-亚精胺。通过Sephacryl S-200凝胶过滤法测得纯化的亚精胺N1-乙酰基转移酶的表观分子量为36 kDa，通过SDS/聚丙烯酰胺凝胶电泳测得为18 kDa。当将十二指肠粗制的105,000×g提取物未经预先纯化直接应用于Sephacryl S-200柱时，出现了三个具有亚精胺N1-乙酰基转移酶活性的峰。第一个峰在空体积部分，第二个峰在表观分子量对应于70 kDa的级分中，第三个峰在对应于36 kDa的级分中。这些结果表明，亚精胺N1-乙酰基转移酶以18 kDa亚基的二聚体形式存在，并在完整细胞中以与其他成分或蛋白质结合的形式稳定存在。
