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Table 2 Activities of the new mutants obtained by single or multiple combinations of aminoacid substitutions

From: New active site oriented glyoxyl-agarose derivatives of Escherichia colipenicillin G acylase

N. of Lys introduced Mutants Expression of the 95 kDa pre-pro-enzyme Enzyme processinga U(NIPAB)/mlb U(NIPAB)/mg
0 Wt + + 25.0 5.0
1 αE194K + + 23.2 5.3
  βD494K + + 27.0 5.4
  βD403K + + 13.9 4.6
  βR495K + - n.d.c n.d.c
  βD216K + - n.d.c n.d.c
2 αE194K, βD494K + + 20.0 4.0
  βD216K, βG219K + - n.d.c n.d.c
  αN202K, αN205K - - n.d.c n.d.c
3 βD13K, βE272K, βR276K (3K) + + 19.0 4.3
4 (3K)+ βD494K + - n.d.c n.dc.
  (3K)+ βR495K + - n.d.c n.d.c
5 3K+ βD216K+βG219K + - n.d.c n.d.c
  1. aEnzyme processing means presence of the two 65 and 24 kDa subunits in the SDS-PAGE analysis of periplasmic extract.
  2. bU, units are μmol of NIPAB hydrolyzed min-1 ml-1 of periplasmic extract.
  3. cn.d., means not detectable enzyme activity.