Goobar-Larsson L, Larsson P T, Debouck C, Towler E M
Microbiology and Tumorbiology Center, MTC, Karolinska Institute, Stockholm, Sweden.
Biochem Biophys Res Commun. 1996 Mar 7;220(1):203-7. doi: 10.1006/bbrc.1996.0381.
HIV-1 reverse transcriptase (RT) can specifically enhance HIV-1 proteinase activity in vitro and in eukaryotic cells (1). To determine if the effect of RT on proteinase activity was due to changes in the equilibrium dimerization constant of the proteinase or the stability of the proteinase dimer, we studied the effect of RT on a genetically engineered covalent dimer (tethered dimer) of the proteinase. RT was found to increase the activity of the tethered dimer independent of pH and ionic strength. The effect of RT on the kinetic constants (Km and kcat) of the wild type HIV-1 proteinase and its tethered dimer were also determined. These results show that RT can increase the enzymatic catalytic efficiency and substrate affinity of the proteinase, by a mechanism independent of promoting dimer formation.
HIV-1逆转录酶（RT）在体外和真核细胞中均可特异性增强HIV-1蛋白酶的活性（1）。为了确定RT对蛋白酶活性的影响是否归因于蛋白酶平衡二聚化常数的变化或蛋白酶二聚体的稳定性，我们研究了RT对蛋白酶的基因工程共价二聚体（拴系二聚体）的影响。发现RT可提高拴系二聚体的活性，且不受pH和离子强度的影响。我们还测定了RT对野生型HIV-1蛋白酶及其拴系二聚体动力学常数（Km和kcat）的影响。这些结果表明，RT可通过一种不依赖于促进二聚体形成的机制来提高蛋白酶的酶催化效率和底物亲和力。
