Yan T R, Ho S C, Hou C L
Department of Bioengineering, Tatung Institute of Technology, Taipei, Taiwan, R.O.C.
Biosci Biotechnol Biochem. 1992 May;56(5):704-7. doi: 10.1271/bbb.56.704.
An X-prolyl dipeptidyl aminopeptidase (X-PDAP; EC 3.4.14.5) was identified to be loosely bound on the inner cell membrane fraction of Lactococcus lactis subsp. cremoris nTR. The biosynthesis of X-PDAP was continuously increased before the late-log growth phase of the bacteria. Both Gly-Pro-pNA and Ala-Ala-pNA were hydrolyzed by X-PDAP; the kcat/Km value of the former was about 10-fold that of the latter. The Ki of X-Pro and Pro-X were more specific to X-PDAP than those of X-Ala. The enzyme splitting a dipeptide sequentially from beta-casomorphin as a model catalytic pattern was identified and some properties of the enzyme were further characterized.
一种X-脯氨酰二肽基氨基肽酶（X-PDAP；EC 3.4.14.5）被鉴定为松散地结合在乳酸乳球菌亚种cremoris nTR的内膜组分上。在细菌对数生长后期之前，X-PDAP的生物合成持续增加。Gly-Pro-pNA和Ala-Ala-pNA均可被X-PDAP水解；前者的kcat/Km值约为后者的10倍。X-脯氨酸和脯氨酸-X的Ki对X-PDAP的特异性高于X-丙氨酸。鉴定了以β-酪蛋白吗啡作为模型催化模式依次切割二肽的酶，并进一步表征了该酶的一些特性。
