Peptide Chemistry Laboratory, Institute of Biochemistry and Biophysics, University of Tehran , 16 Azar Street, 14176-14335 Tehran, Iran.
Centre for Microbial Diseases and Immunity Research, University of British Columbia , 2259 Lower Mall Research Station, Vancouver, BC V6T 1Z4, Canada.
J Med Chem. 2016 Apr 14;59(7):3079-86. doi: 10.1021/acs.jmedchem.5b01740. Epub 2016 Mar 18.
Synthetic bactenecins 1 (HHC-10) and 10 (HHC-36), with excellent activities against bacterial superbugs, display low tryptic stability. To investigate factors influencing this stability, a series of 1/10 derived peptides bearing arginine and lysine analogues with varied methylene chains as well as all-d-isomers were synthesized. Whereas incorporation of d-/l-nonproteinogenic amino acids into the turn-forming peptides did not dramatically affect the antimicrobial activities, the degree of peptide cleavage decreased significantly in peptides with the shortest length of cationic side chain and was influenced by the relative conformational stabilities of the turn structure and the stereoselectivity of tryptic digestion. The site of enzymatic cleavage was located at the less conformationally hindered position distant from the turn motif. Isothermal titration calorimetry showed strong and weak constant increments in the generated heat of enzymatic reaction of unstable and slowly degradable peptides with trypsin, respectively, and suggested a one-site binding model for the enthalpy-driven all-d-peptide-trypsin interactions.
合成抗菌肽 1（HHC-10）和 10（HHC-36）对超级细菌具有优异的活性，但对胰蛋白酶的稳定性较低。为了研究影响稳定性的因素，我们合成了一系列带有精氨酸和赖氨酸类似物的 1/10 衍生肽，其侧链具有不同的亚甲基链和全 d-异构体。虽然将 d-/l-非蛋白氨基酸引入到转角形成肽中并没有显著影响抗菌活性，但在具有最短阳离子侧链长度的肽中，肽的切割程度显著降低，这受到转角结构的相对构象稳定性和胰蛋白酶消化的立体选择性的影响。酶切位点位于远离转角结构的构象受限较小的位置。等温滴定量热法显示，不稳定和缓慢降解的肽与胰蛋白酶的酶反应产生的热量具有强和弱的恒定增量，这分别表明全 d-肽-胰蛋白酶相互作用的焓驱动为一价结合模型。
