Bagossi P, Cheng Y S, Oroszlan S, Tözsér J
Department of Biochemistry, University Medical School of Debrecen, Hungary.
Protein Eng. 1996 Nov;9(11):997-1003. doi: 10.1093/protein/9.11.997.
Mutations were introduced into the active site triplet (Asp-Thr-Gly) of one or both subunits of a linked dimer of human immunodeficiency virus type 1 proteinase. Mutation of Thr to Ser in one or both subunits did not alter the activity of the enzyme substantially, whereas its mutation to Asn in one subunit caused a dramatic decrease in catalytic efficiency. Mutation of Gly to Val in one subunit also yielded an enzyme with very low activity. The enzymes containing Thr-->Asn and Gly-->Val mutations in both subunits resulted in inactive enzymes, based on their inability to self-process and on assay with an oligopeptide substrate. The dramatic decrease in enzyme efficiency of the mutants was interpreted using molecular models of the enzymes.
在人免疫缺陷病毒1型蛋白酶连接二聚体的一个或两个亚基的活性位点三联体（天冬氨酸-苏氨酸-甘氨酸）中引入突变。一个或两个亚基中的苏氨酸突变为丝氨酸基本不会改变酶的活性，而一个亚基中的苏氨酸突变为天冬酰胺会导致催化效率大幅下降。一个亚基中的甘氨酸突变为缬氨酸也会产生活性非常低的酶。基于其无法自我加工以及对寡肽底物的检测，两个亚基都含有苏氨酸→天冬酰胺和甘氨酸→缬氨酸突变的酶没有活性。利用这些酶的分子模型解释了突变体酶效率的大幅下降。
