Keynan S, Hooper N M, Turner A J
Department of Biochemistry and Molecular Biology, University of Leeds, UK.
FEBS Lett. 1994 Jul 25;349(1):50-4. doi: 10.1016/0014-5793(94)00637-7.
Pig renal membrane dipeptidase cDNA has been expressed in COS-1 cells. Directed mutagenesis was used to investigate the roles of some conserved histidyl and aspartyl residues. Mutation of His219 to Arg, Lys or Leu results in complete abolition of enzyme activity, although the mutants are expressed at the cell-surface. Residues in a proposed motif (DHXDH; residues 269-273) for zinc binding have been mutated individually. Each retained activity comparable to that of the wild-type, excluding an essential role for components of this motif. The zinc-binding ligands in membrane dipeptidase therefore represent a novel domain for a metallopeptidase with His219 being one candidate.
猪肾膜二肽酶cDNA已在COS-1细胞中表达。采用定点诱变来研究一些保守的组氨酸和天冬氨酸残基的作用。将His219突变为Arg、Lys或Leu会导致酶活性完全丧失，尽管这些突变体在细胞表面表达。对于一个假定的锌结合基序（DHXDH；第269 - 273位残基）中的残基进行了单独突变。每个突变体保留的活性与野生型相当，排除了该基序成分的关键作用。因此，膜二肽酶中的锌结合配体代表了金属肽酶的一个新结构域，His219是其中一个候选者。
