Joy K W, Ellis R J
Biochim Biophys Acta. 1975 Jan 6;378(1):143-51. doi: 10.1016/0005-2787(75)90145-8.
Envelope membranes were isolated from washed chloroplasts of pea seedlings. As judged by the protein-to-chlorophyll ratio, average preparations contain less than 8 percent contamination with internal lamellar membranes. Electrophoresis on sodium dodecylsulphate polyacrylamide gels shows that the envelope membranes contain at least 25 polypeptides. The molecular weight distribution of the envelope polypeptides is different from that of the lamellar polypeptides, there being more polypeptides of molecular weights above 50 000 in the envelopes. Two envelope polypeptides become labelled when isolated intact chloroplasts are incubated in the light with (35S) methionine. One of these is similar in molecular weight to the main polypeptide labelled in lamellae, but the other is unique to the envelope fraction. Incorporation of label into both polypeptides is totally light-dependent and is inhibited by chloramphenicol. When (35S) methionine is fed to detached pea shoots with and without cycloheximide, the labelling of other envelope polypeptides is inhibited. We conclude that two polypeptides of the chloroplast envelop are synthesised by chloroplast ribosomes.
从豌豆幼苗洗净的叶绿体中分离出包膜。根据蛋白质与叶绿素的比例判断，平均制剂中内部片层膜的污染少于8%。在十二烷基硫酸钠聚丙烯酰胺凝胶上进行电泳显示，包膜含有至少25种多肽。包膜多肽的分子量分布与片层多肽不同，包膜中分子量高于50000的多肽更多。当完整的叶绿体在光下与（35S）甲硫氨酸一起孵育时，两种包膜多肽会被标记。其中一种在分子量上与片层中标记的主要多肽相似，但另一种是包膜部分特有的。两种多肽的标记掺入完全依赖于光，并受到氯霉素的抑制。当向有和没有环己酰亚胺的离体豌豆芽饲喂（35S）甲硫氨酸时，其他包膜多肽的标记受到抑制。我们得出结论，叶绿体包膜的两种多肽是由叶绿体核糖体合成的。
