Vance J E, LeBlanc D A, Wingfield P, London R E
Laboratory of Structural Biology, NIEHS, Research Triangle Park, North Carolina 27709, USA.
J Biol Chem. 1997 Jun 20;272(25):15603-6. doi: 10.1074/jbc.272.25.15603.
Kinetic measurements on a fluorescent peptide analog of the p17/p24 cleavage site of the Gag polyprotein demonstrate the conformational selectivity of human immunodeficiency virus, type 1 protease for the trans conformation of the Tyr-Pro bond. A mean cis/trans ratio of 0. 3, and a cis --> trans isomerization rate constant of 0.022 s-1 are determined at T = 22 degrees C. This rate is in excellent agreement with that predicted by 19F NMR studies of structurally analogous peptides containing a fluorine/hydroxyl substitution on the tyrosyl residue. Addition of recombinant human cyclophilin resulted in a significant enhancement of this rate, and it is proposed that this enzyme, which has been shown to be associated with the Gag protein, functions as an auxiliary enzyme for the protease during cleavage in the virion.
对Gag多蛋白p17/p24裂解位点的荧光肽类似物进行动力学测量，结果表明1型人类免疫缺陷病毒蛋白酶对Tyr-Pro键的反式构象具有构象选择性。在T = 22℃时，测得顺式/反式平均比率为0.3，顺式→反式异构化速率常数为0.022 s-1。该速率与通过对在酪氨酸残基上含有氟/羟基取代的结构类似肽进行19F NMR研究所预测的速率非常吻合。添加重组人亲环蛋白导致该速率显著提高，并且有人提出，这种已被证明与Gag蛋白相关的酶，在病毒粒子裂解过程中作为蛋白酶的辅助酶发挥作用。
