PURIFICATION AND COMPARISON OF 2 FORMS OF S-ADENOSYL-L-METHIONINE SYNTHETASE FROM RAT-LIVER
PURIFICATION AND COMPARISON OF 2 FORMS OF S-ADENOSYL-L-METHIONINE SYNTHETASE FROM RAT-LIVER
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DOI：
10.1111/j.1432-1033.1987.tb13699.x
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发表时间：
1987-12-30
期刊：
影响因子：
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通讯作者：
ALEMANY, S
中科院分区：
文献类型：
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作者：
CABRERO, C;PUERTA, J;ALEMANY, S
在大鼠肝脏中仅存在两种S-腺苷-L-甲硫氨酸合成酶形式：高Mr S-腺苷-L-甲硫氨酸合成酶和低Mr S-腺苷-L-甲硫氨酸合成酶，其已被纯化至表观均一性，如十二烷基硫酸钠/聚丙烯酰胺凝胶电泳所判断。高-M4 S-腺苷-L-甲硫氨酸合成酶的表观分子量，通过凝胶过滤测定，为210 kDa，并且是由48.5 kDa亚基构成的四聚体，通过十二烷基硫酸钠/聚丙烯酰胺凝胶电泳估计。低先生S-腺苷-L-甲硫氨酸合成酶的表观分子量，估计通过凝胶过滤，是110 kDa的，是由两个亚基的47 kDa。抗血清对低先生S-腺苷-L-甲硫氨酸合成酶交叉反应的两种形式。反相HPLC运行的胰蛋白酶digestive的高先生和低先生的S-腺苷-L-甲硫氨酸合成酶表明，这两种形式的肽图是非常相似的，如果不是相同的。高分子量S-腺苷-L-甲硫氨酸合成酶活性被S-腺苷-L-甲硫氨酸和焦磷酸抑制。根据使用的剂量，S-腺苷-L-甲硫氨酸激活或抑制低分子量S-腺苷-L-甲硫氨酸合成酶和焦磷酸对这种形式没有影响。这两种合成酶在蛋氨酸的生理浓度下表现出不同的比活性。本报告表明，即使这两种形式是由相同的多肽链构成的，它们也以不同的方式受到甲硫氨酸和反应产物的调节。
Only two S-adenosyl-L-methionine synthetase forms exist in rat liver: high-Mr S-adenosyl-L-methionine synthetase and low-Mr S-adenosyl-L-methionine synthetase, which have been purified to apparent homogeneity as judged by sodium dodecyl sulfate/polyacrylamide gel electrophoresis. High-M4 S-adenosyl-L-methionine synthetase had an apparent molecular mass, determined by gel filtration, of 210 kDa and was a tetramer constituted by 48.5-kDa subunits, estimated by sodium dodecyl sulfate/polyacrylamide gel electrophoresis. The apparent molecular mass of low-Mr S-adenosyl-L-methionine synthetase, as estimated by gel filtration, was 110 kDa and was constituted by two subunits of 47 kDa. An antiserum against low-Mr S-adenosyl-L-methionine synthetase cross-reacted with the two forms. Reverse-phase HPLC runs of tryptic digestions of high-Mr and low-Mr S-adenosyl-L-methionine synthetase showed that the peptide maps of the two forms were very similar, if not identical. High-Mr S-adenosyl-L-methionine synthetase activity was inhibited by S-adenosyl-L-methionine and pyrohosphate. Depending on the dose used, S-adenosyl-L-methionine activated or inhibited low-Mr S-adenosyl-L-methionine synthetase and pyrophosphate had no effect on this form. The two synthetases showed a different specific activity at the physiological concentration of methionine. This report shows that even though the two forms are constructed of the same polypeptide chains, they are regulated in a different manner by methionine and by the products of the reaction.