Properties of S-adenosyl-L-methionine-magnesium-protoporphyrin IX methyltransferase from barley
Properties of S-adenosyl-L-methionine-magnesium-protoporphyrin IX methyltransferase from barley
复制标题
大麦 S-腺苷-L-甲硫氨酸-镁-原卟啉 IX 甲基转移酶的特性
DOI：
10.1093/oxfordjournals.pcp.a075671
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发表时间：
1978
影响因子：
4.9
通讯作者：
M. Pšenák
中科院分区：
文献类型：
--
作者：
J. Shieh;G. Miller;M. Pšenák
绿大麦幼苗中存在s -腺苷- l-蛋氨酸-镁-原卟啉IX甲基转移酶（EC 2.1.1.11）。用鱼精蛋白和硫酸铵沉淀法纯化该酶20倍。该酶在较宽的pH范围内具有活性，pH为7.5时活性最高。mg -原卟啉IX和s -腺苷蛋氨酸的km值分别为48 μM和39 μM；s -腺苷基蛋氨酸和s -腺苷基同型半胱氨酸是s -腺苷基蛋氨酸的竞争性抑制剂；血红素对mg -原卟啉IX的抑制是非竞争性的；硫醇类化合物对酶活性有刺激作用。讨论了该酶的性质，并与其他生物的酶进行了比较。
S-Adenosyl-L-methionine-magnesium-protoporphyrin IX methyltransferase (EC 2.1.1.11) is present in greening barley seedlings associated with the particulate fraction. This enzyme was purified 20 fold using protamine and ammonium sulfate precipitation. The enzyme was active over a wide pH range with highest activity at pH 7.5. TheKmvalues for Mg-protoporphyrin IX and S-adenosylmethionine were 48 and 39 μM, respectively; S-adenosylethionine and S-adenosyihomocysteine were competitive inhibitors with respect to S-adenosylmethionine; hemin inhibition was non-competitive with respect to Mg-protoporphyrin IX; thiol compounds exhibited a stimulatory effect on enzyme activity. The properties of the enzyme are discussed and compared with the enzyme from other organisms.