Ostheimer G J, Starkey J R, Lambert C G, Helgerson S L, Dratz E A
Department of Chemistry, Montana State University, Bozeman 59717.
J Biol Chem. 1992 Dec 15;267(35):25120-8.
Peptide 11, CDPGYIGSR-NH2, is a segment of laminin which blocks tumor cell invasion. A high affinity laminin receptor in tumor cells is thought to be blocked by the carboxyl-terminal YIGSR, and conformational energy calculations suggest that the glycine in YIGSR allows an important conformational bend. We replaced the YIGSR glycine residue in peptide 11 with either D-alanine or L-alanine to allow or disfavor the proposed glycine bend. We found the Gly7-->D-Ala7 analog to be equal to peptide 11 in inhibiting tumor cell invasion of basement membrane matrix. The Gly7-->L-Ala7 analog was much less capable of invasion inhibition. Two-dimensional 1H-1H NMR was used to study the solution conformations of the peptide 11 analogs. NOESY experiments revealed close NH-NH contacts in peptide 11 and the D-Ala7 analog, but not in the L-Ala7 analog. Molecular dynamics generated low energy structures with excellent NOE agreement for peptide 11 and its analogs. Both peptide 11 and the D-Ala7 analog, but not the less active L-Ala7 analog, were predicted to have similar bends around Gly7 or D-Ala7. These results suggest that a bend in the YIGSR region of peptide 11 may be important for the binding of laminin to its metastasis-associated receptor.
肽11，CDPGYIGSR-NH2，是层粘连蛋白的一个片段，可阻断肿瘤细胞的侵袭。肿瘤细胞中的一种高亲和力层粘连蛋白受体被认为被羧基末端的YIGSR阻断，构象能量计算表明YIGSR中的甘氨酸允许一个重要的构象弯曲。我们用D-丙氨酸或L-丙氨酸取代了肽11中YIGSR的甘氨酸残基，以允许或不利于所提出的甘氨酸弯曲。我们发现Gly7→D-Ala7类似物在抑制肿瘤细胞侵袭基底膜基质方面与肽11相当。Gly7→L-Ala7类似物抑制侵袭的能力则弱得多。二维1H-1H NMR被用于研究肽11类似物的溶液构象。NOESY实验揭示了肽11和D-Ala7类似物中有紧密的NH-NH接触，但在L-Ala7类似物中没有。分子动力学生成了与肽11及其类似物的NOE吻合度极佳的低能量结构。肽11和D-Ala7类似物，但活性较低的L-Ala7类似物则不然，预计在Gly7或D-Ala7周围有相似的弯曲。这些结果表明，肽11的YIGSR区域中的弯曲可能对层粘连蛋白与其转移相关受体的结合很重要。
