Steinkühler C, Biasiol G, Brunetti M, Urbani A, Koch U, Cortese R, Pessi A, De Francesco R
Istituto di Ricerche di Biologia Molecolare P. Angeletti (IRBM), Rome, Italy.
Biochemistry. 1998 Jun 23;37(25):8899-905. doi: 10.1021/bi980313v.
The nonstructural protein NS3 of the hepatitis C virus (HCV) harbors a serine protease domain that is responsible for most of the processing events of the nonstructural region of the polyprotein. Its inhibition is presently regarded as a promising strategy for coping with the disease caused by HCV. In this work, we show that the NS3 protease undergoes inhibition by the N-terminal cleavage products of substrate peptides corresponding to the NS4A-NS4B, NS4B-NS5A, and NS5A-NS5B cleavage sites, whereas no inhibition is observed with a cleavage product of the intramolecular NS3-NS4A junction. The Ki values of the hexamer inhibitory products [Ki(NS4A) = 0.6 microM, Ki(NS5A) = 1.4 microM, and Ki(NS4B) = 180 microM] are lower than the Km values of the respective substrate peptides [Km(NS4A-NS4B) = 10 microM, Km(NS5A-NS5B) = 3.8 microM, and Km(NS4B-NS5A) > 1000 microM]. Mutagenesis experiments have identified Lys136 as an important determinant for product binding. The phenomenon of product inhibition can be exploited to optimize peptide inhibitors of NS3 protease activity that may be useful in drug development.
丙型肝炎病毒（HCV）的非结构蛋白NS3含有一个丝氨酸蛋白酶结构域，该结构域负责多聚蛋白非结构区域的大部分加工过程。目前，抑制该蛋白酶被认为是应对HCV所致疾病的一种有前景的策略。在本研究中，我们发现NS3蛋白酶会受到对应于NS4A-NS4B、NS4B-NS5A和NS5A-NS5B切割位点的底物肽N端切割产物的抑制，而分子内NS3-NS4A连接点的切割产物未观察到抑制作用。六聚体抑制产物的Ki值[Ki(NS4A) = 0.6 microM，Ki(NS5A) = 1.4 microM，Ki(NS4B) = 180 microM]低于各自底物肽的Km值[Km(NS4A-NS4B) = 10 microM，Km(NS5A-NS5B) = 3.8 microM，Km(NS4B-NS5A) > 1000 microM]。诱变实验已确定Lys136是产物结合的重要决定因素。产物抑制现象可用于优化NS3蛋白酶活性的肽抑制剂，这可能对药物开发有用。
