3、羧肽酶A(carboxypeptidase A,CpA) 307AA;单体酶，结合有Zn2+。 生物功能是催化肽链C末端肽键的水解。 Carboxypeptidase A +H20 ++H,N-C- CH2 OH OH
3、羧肽酶A（carboxypeptidase A，CpA） 307AA；单体酶,结合有Zn2+ 。 生物功能是催化肽链C末端肽键的水解
Zn2+ 60 307 140 120 Figure Three-dimensional structure of carboxypeptidase A.Only the a-carbon atoms and the zinc ion (shaded circle near the center)are shown.[From W.N.Lipscomb.Proc.Robert A. Welch Found.Conf.Chem.Res.15(1971):134.]
Zn2+
His 196 His 69 Figure A zinc ion is coordinated to two histi- dine side chains and a glutamate side chain at the active site of carboxypep- tidase A.A water molecule coordi- nated to the zinc is not shown here. [After D.M.Blow and T.A.Steitz. X-ray diffraction studies of enzymes, Ann.Rev.Biochem.39:78.Copyright C 1970 by Annual Reviews,Inc.All rights reserved.]
Nonpolar pocket +H2N NH Arg 145 Tyr 248 Glu 270 Figure Schematic representation of the bind- ing of glycyltyrosine to the active site of carboxypeptidase A.The pro- posed catalytically active complex is shown here
1 Tyr 248 Glu 270 ○His196 Arg 145 Glu 72 His 69 Three-dimensional structure of glycyltyrosine at the active site of carboxypeptidase A.Glycyltyrosine,the substrate,is shown in red. [After D.M.Blow and T.A.Steitz.X-ray diffraction studies of enzymes,Ann.Rev.Biochem.39:79.Copyright C 1970 by Annual Reviews,Inc.All rights reserved.]