Roof R W, Luescher I F, Unanue E R
Department of Pathology, Washington University School of Medicine, Saint Louis, MO 63110.
Proc Natl Acad Sci U S A. 1990 Mar;87(5):1735-9. doi: 10.1073/pnas.87.5.1735.
The binding of a lysozyme and ovalbumin peptide to purified class II major histocompatibility molecules in detergents was increased by the addition of certain lipids. Natural lipids from B lymphoma cells enhanced the binding and so did phosphatidylcholine, phosphatidylserine, phosphatidylinositol, and cardiolipin. Phosphatidylethanolamine, sphingomyelin, and cholesterol had no effect. There was no major difference between the effects of a phospholipid and its lyso derivative. As studied with phosphatidylcholine, the increase in peptide binding was also dependent on the fatty acid composition of the lipid. The binding affinity was increased 10- to 50-fold in the presence of lipid as a result of an increase in the association rate while the off-rate remained essentially unchanged. Our results suggest that lipids, directly or indirectly, induce conformational changes in class II molecules that favor their peptide-binding property.
在去污剂中，某些脂质的添加增加了溶菌酶和卵清蛋白肽与纯化的II类主要组织相容性分子的结合。来自B淋巴瘤细胞的天然脂质增强了这种结合，磷脂酰胆碱、磷脂酰丝氨酸、磷脂酰肌醇和心磷脂也有同样的作用。磷脂酰乙醇胺、鞘磷脂和胆固醇则没有效果。磷脂及其溶血衍生物的作用没有显著差异。以磷脂酰胆碱进行研究时，肽结合的增加也取决于脂质的脂肪酸组成。由于缔合速率增加而解离速率基本不变，脂质存在时结合亲和力提高了10至50倍。我们的结果表明，脂质直接或间接诱导II类分子发生构象变化，从而有利于其肽结合特性。
