Chich J F, Chapot-Chartier M P, Ribadeau-Dumas B, Gripon J C
Unité Protéines, Station de Recherches Laitières, INRA 78352, Jouy-en Josas, France.
FEBS Lett. 1992 Dec 14;314(2):139-42. doi: 10.1016/0014-5793(92)80960-o.
The active site serine of the X-prolyl dipeptidyl aminopeptidase from Lactococcus lactis (PepX) was identified. The enzyme was labeled by [3H]DFP, treated by CNBr and the resulting peptides were separated by reverse-phase-HPLC. The main radiolabeled peptide was sequenced. Ser-348, in the following sequence, Gly-Lys-Ser-Tyr-Leu-Gly, was identified as the active site serine. A sequence comparison between the active site of PepX and other serine proteases was made, showing only limited sequence homologies in this area. The consensus sequence surrounding the active site serine in the three known X-prolyl dipeptidyl aminopeptidases (mammalian DPPIV, yeast DPAB and PepX) is G-X-S-Y-X-G, where X is a non-conserved amino acid.
鉴定了乳酸乳球菌X-脯氨酰二肽基氨基肽酶（PepX）的活性位点丝氨酸。该酶用[3H]DFP标记，用溴化氰处理，所得肽通过反相高效液相色谱分离。对主要的放射性标记肽进行了测序。在以下序列Gly-Lys-Ser-Tyr-Leu-Gly中的Ser-348被鉴定为活性位点丝氨酸。对PepX的活性位点与其他丝氨酸蛋白酶进行了序列比较，结果表明该区域仅存在有限的序列同源性。三种已知的X-脯氨酰二肽基氨基肽酶（哺乳动物二肽基肽酶IV、酵母DPAB和PepX）活性位点丝氨酸周围的共有序列为G-X-S-Y-X-G，其中X为非保守氨基酸。
