Kiss András L, Szeltner Zoltán, Fülöp Vilmos, Polgár László
Institute of Enzymology, Biological Research Center, Hungarian Academy of Sciences, P.O. Box 7, H-1518 Budapest 112, Hungary.
FEBS Lett. 2004 Jul 30;571(1-3):17-20. doi: 10.1016/j.febslet.2004.06.054.
Acylaminoacyl peptidase is a member of the prolyl oligopeptidase family. Amino acid sequence alignment suggests that the stabilization of the tetrahedral intermediate should be mediated by His507 rather than by a tyrosine residue found in the other family members of this serine peptidase group. The pH dependence of k(cat)/K(m) did not reveal any effect of His507. Substitution of an alanine for His507 gave the same bell-shaped pH rate profile with the same pK(a) values (7.0 and 8.7). However, the value of the rate constant was 85 times lower with the modified enzyme, which indicated that His507 is an important residue that is probably involved in the formation of the 3-dimensional structure.
酰基氨基酰肽酶是脯氨酰寡肽酶家族的一员。氨基酸序列比对表明，四面体中间体的稳定应由His507介导，而非该丝氨酸肽酶组其他家族成员中发现的酪氨酸残基。k(cat)/K(m)对pH的依赖性未显示出His507有任何影响。用丙氨酸取代His507得到了相同的钟形pH速率曲线以及相同的pK(a)值（7.0和8.7）。然而，修饰后的酶的速率常数降低了85倍，这表明His507是一个重要残基，可能参与三维结构的形成。
