Abraham A K, Kolseth S, Pihl A
Eur J Biochem. 1982 May 17;124(2):383-8. doi: 10.1111/j.1432-1033.1982.tb06604.x.
Affinity chromatography of wheat germ extracts on a chitin column increased the rate and extent of protein synthesis, programmed by rabbit globin mRNA. Addition of purified wheat germ agglutinin to the chitin-treated extract reduced the rate of protein synthesis to about the levels seen in the untreated extracts. Experiments where the ratio of messenger to extract and the ratio of supernatant to ribosomes were varied, indicated that addition of wheat germ agglutinin reduced the amount of available ribosomes. Reduced and carboxymethylated wheat germ agglutinin failed to inhibit protein synthesis and was unable to bind to the ribosomes. However, labelled intact agglutinin was found to be bound to ribosomes. The bound agglutinin was not released by acid treatment. The inhibiting effect of wheat germ, agglutinin on protein synthesis could not be counteracted by addition of N-acetyl-D-glucosamine or sialic acid, whereas thiols partially diminished the inhibition. The data indicate that wheat germ agglutinin binds reversibly to ribosomes, probably through mixed disulfide formation, and that chitin treatment increases the ability of wheat germ extracts to support protein synthesis, at least in part, by removing the wheat germ agglutinin. The possibility that chitin treatment also removed other inhibitors of protein synthesis cannot be excluded.
用几丁质柱对小麦胚芽提取物进行亲和层析，提高了由兔珠蛋白信使核糖核酸编程的蛋白质合成的速率和程度。向经几丁质处理的提取物中添加纯化的麦胚凝集素，可使蛋白质合成速率降低至未处理提取物中的水平。改变信使与提取物的比例以及上清液与核糖体的比例的实验表明，添加麦胚凝集素会减少可用核糖体的数量。还原和羧甲基化的麦胚凝集素不能抑制蛋白质合成，也不能与核糖体结合。然而，发现标记的完整凝集素与核糖体结合。结合的凝集素不会因酸处理而释放。添加N-乙酰-D-葡萄糖胺或唾液酸不能抵消麦胚凝集素对蛋白质合成的抑制作用，而硫醇可部分减轻这种抑制作用。数据表明，麦胚凝集素可能通过形成混合二硫键与核糖体可逆结合，几丁质处理提高小麦胚芽提取物支持蛋白质合成的能力，至少部分是通过去除麦胚凝集素实现的。不能排除几丁质处理也去除了其他蛋白质合成抑制剂的可能性。
