Bao SJ, Xie DL, Zhang JP, Chang WR, Liang DC. Crystal structure of desheptapeptide(B24-B30)insulin at 1.6 A resolution: implications for receptor binding.
Proc Natl Acad Sci U S A 1997;
94:2975-80. [PMID:
9096331 PMCID:
PMC20307 DOI:
10.1073/pnas.94.7.2975]
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Abstract
The crystal structure of desheptapeptide (B24-B30) insulin (DHPI), a virtually inactive analog of insulin, was determined at 1.6 A resolution. In the refined structure model, DHPI retains three alpha-helices (A1-A8, A12-A18, and B9-B19) as its structural framework, while great conformational changes occur in the N and C termini of B-chain. The beta-turn, which lies in B20-B30 in insulin and insulin analogs with high potency, no longer exists in DHPI. Relative motion is observed among the three alpha-helices, each as a rigid functional group. In contrast, a region covering B5-B6 and A6-A11 exhibits a relatively stable conformation. We interpret our results as identifying: (i) the importance of beta-turn in determining the receptor-binding potency of insulin and (ii) a leading role of PheB24 in maintaining the beta-turn structure.
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