Bhaya D, Castelfranco P A
Department of Botany, University of California at Davis, Davis, California 95616.
Plant Physiol. 1986 Aug;81(4):960-4. doi: 10.1104/pp.81.4.960.
In addition to chlorophyll-protein complexes, other proteins were labeled when isolated developing pea (Pisum sativum L.) chloroplasts were incubated with [(14)C]-5-aminolevulinic acid. The major labeled band (M(r) = 43 kilodaltons by lithium dodecyl sulfate-polyacrylamide gel electrophoresis) was labeled even in the presence of chloramphenicol. Heme-dependent peroxidase activity (as detected by the tetramethyl benzidine-H(2)O(2) stain) was not visibly associated with this band. The radioactive band was stable to heat, 5% HCl in acetone, and was absent if the incubation with [(14)C]-5-aminolevulinic acid was carried out in the presence of N-methyl protoporphyrin IX dimethyl ester (a specific inhibitor of ferrochelatase). Organic solvent extraction procedures for the enrichment of cytochrome f from chloroplast membranes also extracted this unknown labeled product. It was concluded that this labeled product was probably a c-type cytochrome; however, the possibility that it might be a protein containing a covalently linked linear tetrapyrrole was not ruled out.
除了叶绿素 - 蛋白质复合物外，当分离的发育中的豌豆（Pisum sativum L.）叶绿体与[（14）C]-5-氨基乙酰丙酸一起孵育时，其他蛋白质也被标记。即使在氯霉素存在的情况下，主要的标记条带（通过十二烷基硫酸钠 - 聚丙烯酰胺凝胶电泳测定，Mr = 43千道尔顿）也被标记。血红素依赖性过氧化物酶活性（通过四甲基联苯胺 - H2O2染色检测）与该条带没有明显关联。该放射性条带对热、丙酮中的5%HCl稳定，并且如果在N - 甲基原卟啉IX二甲酯（铁螯合酶的特异性抑制剂）存在下与[（14）C]-5-氨基乙酰丙酸进行孵育则不存在。从叶绿体膜中富集细胞色素f的有机溶剂提取程序也提取了这种未知的标记产物。得出的结论是，这种标记产物可能是一种c型细胞色素；然而，它可能是一种含有共价连接的线性四吡咯的蛋白质的可能性并未被排除。
