Izawa S, Good N E
Department of Botany and Plant Pathology, Michigan State University, East Lansing, Michigan.
Plant Physiol. 1966 Mar;41(3):544-52. doi: 10.1104/pp.41.3.544.
Spinach chloroplasts isolated in media containing salts and the rare chloroplasts which are still within their envelopes alike retain grana similar to those seen in chloroplasts in situ.Chloroplasts isolated in low-salt media lose their grana without losing any chlorophyll. These grana-free chloroplasts are considerably swollen and consist almost entirely of continuous sheets of paired-membrane structures. These double structures, the lamellae, are only loosely held together, primarily at the edges, by tenuous material which does not react with permanganate.Addition of salts (methylamine hydrochloride, NaCl, MgCl(2)) to the grana-free low-salt chloroplasts provide strong interlamellar attractions. These attractions result in a stacking of the lamellae which is sometimes almost random but sometimes results in regular structures indistinguishable from the original grana.The phosphorylation-uncoupler atebrin causes further swelling of the chloroplasts in the absence of electron transport by increasing the space between the paired membranes of the lamellae.The rapid electron transport (Hill reaction) made possible by atebrin-uncoupling is associated with a great decrease in chloroplast volume. This decrease results from a collapsing together of the widely separated lamellar membrane pairs. The pairs approach each other so closely that they usually appear as a single membrane when viewed with the electron microscope. The much slower electron transport which occurs in the absence of uncouplers is associated with a similar but smaller decrease in the space between the lamellar membrane pairs.Chloroplasts swell during the rapid electron transport made possible by the phosphorylation-uncoupler methylamine. This swelling is accompanied by a degree of membrane distortion which precludes an interpretation of the mechanism. As with atebrin-faciliated electron transport, obviously paired membranes disappear but it is not yet clear whether this is by association or dissociation of the pairs.
在含有盐的培养基中分离出的菠菜叶绿体，以及仍处于其包膜内的稀有叶绿体，都保留着类似于原位叶绿体中所见的基粒。在低盐培养基中分离出的叶绿体失去了它们的基粒，但没有损失任何叶绿素。这些无基粒的叶绿体显著肿胀，几乎完全由连续的成对膜结构片层组成。这些双层结构，即片层，仅在边缘处由不与高锰酸盐反应的细丝状物质松散地连接在一起。向无基粒的低盐叶绿体中添加盐（盐酸甲胺、氯化钠、氯化镁）会产生强烈的片层间吸引力。这些吸引力导致片层堆叠，有时几乎是随机的，但有时会形成与原始基粒难以区分的规则结构。磷酸化解偶联剂阿的平在没有电子传递的情况下，通过增加片层成对膜之间的空间，导致叶绿体进一步肿胀。阿的平解偶联使快速电子传递（希尔反应）成为可能，这与叶绿体体积的大幅减小有关。这种减小是由于广泛分离的片层膜对相互折叠在一起。这些膜对彼此靠得非常近，以至于在电子显微镜下观察时通常看起来像一层膜。在没有解偶联剂的情况下发生的慢得多的电子传递，与片层膜对之间空间的类似但较小的减小有关。在磷酸化解偶联剂甲胺使快速电子传递成为可能的过程中，叶绿体肿胀。这种肿胀伴随着一定程度的膜变形，这使得对其机制的解释变得困难。与阿的平促进的电子传递一样，显然成对的膜消失了，但尚不清楚这是通过膜对的结合还是解离。
