Lorand L, Parameswaran K N, Stenberg P, Tong Y S, Velasco P T, Jönsson N A, Mikiver L, Moses P
Biochemistry. 1979 May 1;18(9):1756-65. doi: 10.1021/bi00576a019.
The amine specificity of guinea pig liver transglutaminase, a model enzyme for endo-gamma-glutamine:epsilon-lysin transferases, was explored with the aid of synthetic substrates of high apparent affinities. As exemplified by dansyl- (5-dimethylamino-1-naphthalenesulfonyl), (2,4-dinitrobenzenesulfonyl)-, and (2,4,6-triisopropylbenzenesulfonyl)-cadaverines--each of which showed affinities of approximately 4 x 10(7) M-1--the best amine substrates carried a large hydrophobic substituent attached to an alkylamine side chain of about 7.2 A in length. Altogether, our results point to the importance of a hydrophobic binding region in the enzyme from where the alkyl side chain reaches into a narrow crevice toward the active center and positions the primary amine of the substrate for attacking the carbonyl group of the acyl enzyme intermediate.
豚鼠肝脏转谷氨酰胺酶是一种用于研究内切γ-谷氨酰胺：ε-赖氨酸转移酶的模型酶，借助具有高表观亲和力的合成底物对其胺特异性进行了研究。以丹磺酰基-（5-二甲基氨基-1-萘磺酰基）、（2,4-二硝基苯磺酰基）-和（2,4,6-三异丙基苯磺酰基）-尸胺为例——每一种的亲和力约为4×10⁷ M⁻¹——最佳胺底物带有一个大的疏水取代基，连接在长度约为7.2 Å的烷基胺侧链上。总之，我们的结果表明该酶中疏水结合区域的重要性，烷基侧链从该区域伸向朝向活性中心的狭窄裂缝，并将底物的伯胺定位以攻击酰基酶中间体的羰基。
