Kloosterman D A, Scahill T A, Hillman R M, Cleary D L, Kubiak T M
Physical and Analytical Chemistry Research, Upjohn Company, Kalamazoo, MI 49001.
Pept Res. 1991 Mar-Apr;4(2):72-8.
Relative growth hormone-releasing potencies of bovine growth hormone-releasing factor (bGRF) analogs bGRF(1-44)NH2 (I), Leu27-bGRF(1-29)NH2 (II) and D-Ala2, Leu27-bGRF(1-29)NH2 (III) in in vitro bovine anterior pituitary cell cultures were determined to be 100%, 48% and 77%, respectively. The potencies of II and III, although numerically different, were not statistically different. Leu27-bGRF(3-29)NH2 (IV) was approximately 10,000 times less potent than 1. 1H NMR studies of peptides II, III and IV in 35% d3-2,2,2-trifluorethanol (TFE)/65% phosphate buffer at pH 4 revealed very similar, highly helical secondary structures in the 8-29 region, with only subtle differences at the N-termini. This lack of correlation between secondary structure in solution and in vitro bioactivity suggests that either 1) the biological conformations induced at the GRF receptor for II and III vs. IV are different from those generated in TFE/buffer, 2) similar secondary structures may be necessary but not sufficient for the observed bioactivity or 3) residues 1 and 2 of analogs II and III are important contact residues crucial for effective GRF-receptor interaction.
在体外牛垂体前叶细胞培养中，测定了牛生长激素释放因子（bGRF）类似物bGRF(1 - 44)NH₂（I）、Leu²⁷ - bGRF(1 - 29)NH₂（II）和D - Ala², Leu²⁷ - bGRF(1 - 29)NH₂（III）的相对生长激素释放效力，分别为100%、48%和77%。II和III的效力虽然在数值上不同，但在统计学上没有差异。Leu²⁷ - bGRF(3 - 29)NH₂（IV）的效力比I低约10000倍。在pH 4的35% d₃ - 2,2,2 - 三氟乙醇（TFE）/65%磷酸盐缓冲液中对肽II、III和IV进行的¹H NMR研究表明，在8 - 29区域具有非常相似的高度螺旋二级结构，仅在N端有细微差异。溶液中的二级结构与体外生物活性之间缺乏相关性表明，要么1）II和III与IV在生长激素释放因子（GRF）受体上诱导的生物学构象与在TFE/缓冲液中产生的不同，2）相似的二级结构对于观察到的生物活性可能是必要的，但不是充分的，要么3）类似物II和III的第1和第2位残基是有效GRF - 受体相互作用的重要接触残基。
