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Site‐directed mutagenesis of Lys 600 in phospho enol pyruvate carboxylase of Flaveria trinervia : its roles in catalytic and regulatory functions
Author(s) -
Gao Y.,
Woo K.C.
Publication year - 1995
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(95)01189-l
Subject(s) - pyruvate carboxylase , chemistry , mutagenesis , enol , biochemistry , site directed mutagenesis , catalysis , mutation , gene , enzyme , mutant
Phospho enol pyruvate carboxylases from various organisms contain two conserved lysine residues. In the C 4 dicot Flaveria trinervia , one of these residues is Lys 600 . Converting this Lys 600 to Arg 600 or Thr 600 mainly increased the K m values and but had minimal effect on the V max . The K m for PEP, Mg 2+ increased by up to 3‐fold in Arg 600 and Thr 600 but the K m (HCO 3 − ) increased 9‐fold in Thr 600 , suggesting that Lys 600 might be associated with bicarbonate‐binding. This lysine was not obligatory for enzyme activity although the wild‐type protein showed higher activity at physiological pH and was less inhibited by malate than the two mutants.