Departments of Botany and Biochemistry, University of Glasgow, G12 8QQ, Glasgow, UK.
Planta. 1992 Sep;188(2):225-31. doi: 10.1007/BF00216817.
The pyruvate dehydrogenase complex (PDC) in pea (Pisum sativum L., cv. Little Marvel) was studied immunologically using antibodies to specific subunits of mammalian PDC. Pea mitochondria and chloroplasts were both found to contain PDC, but distinct differences were noted in the subunit relative molecular mass (Mr) values of the individual enzymes in the mitochondrial and chloroplast PDC complexes. In particular, the mitochondrial E3 enzyme (dihydrolipoamide dehydrogenase; EC 1.8.1.4) has a high subunit Mr value of 67 000, while the chloroplast E3 enzyme has a subunit Mr value of 52 000, similar in size to the prokaryotic, yeast ad mammalian E3 enzymes. In addition, component X (not previously noted in plant PDC) was also found to be present in two distinct forms in pea mitochondrial and chloroplast complexes. As in the case of E3, mitochondrial component X has a higher subunit Mr value (67 000) than component X from chloroplasts (48 000), which is similar in size to its mammalian counterpart. The subunit Mr value of E2 (dihydrolipoamide acetyltransferase; EC 2.3.1.12) in both mitochondria and chloroplasts (50 000) is lower than that of mammalian E2 (74 000) but similar to that of yeast E2 (58 000), and is consistent with the presence of only a single lipoyl domain. Neither mitochondria nor chloroplasts showed any appreciable cross-reactivity with antiserum to mammalian E1 (pyruvate dehydrogenase; EC 1.2.4.1). However, mitochondria cross-reacted strongly with antiserum to yeast E1, giving a single band (Mr 41 000) which is thought to be E1a. Chloroplasts showed no cross-reactivity with yeast E1, indicating that the mitochondrial E1a subunit and its chloroplast equivalent are antigenically distinct polypeptides.
豌豆（Pisum sativum L.，cv. Little Marvel）的丙酮酸脱氢酶复合物（PDC）通过针对哺乳动物 PDC 特定亚基的抗体进行免疫学研究。发现豌豆线粒体和叶绿体都含有 PDC，但线粒体和叶绿体 PDC 复合物中各酶的亚基相对分子质量（Mr）值存在明显差异。特别是，线粒体 E3 酶（二氢硫辛酸脱氢酶；EC 1.8.1.4）的亚基 Mr 值很高，为 67000，而叶绿体 E3 酶的亚基 Mr 值为 52000，与原核生物、酵母和哺乳动物 E3 酶的大小相似。此外，还发现 X 组分（以前在植物 PDC 中未注意到）也存在于豌豆线粒体和叶绿体复合物的两种不同形式中。与 E3 情况一样，线粒体 X 组分的亚基 Mr 值（67000）高于叶绿体 X 组分（48000），与哺乳动物 X 组分相似。线粒体和叶绿体中 E2（二氢硫辛酸乙酰基转移酶；EC 2.3.1.12）的亚基 Mr 值（50000）低于哺乳动物 E2（74000），但与酵母 E2（58000）相似，这与仅存在单个脂酰基结构域一致。线粒体和叶绿体均与抗哺乳动物 E1（丙酮酸脱氢酶；EC 1.2.4.1）的血清无明显交叉反应。然而，线粒体与酵母 E1 强烈交叉反应，产生一个单一的条带（Mr 41000），被认为是 E1a。叶绿体与酵母 E1 无交叉反应，表明线粒体 E1a 亚基及其叶绿体对应物是抗原上不同的多肽。
