@entity23909 (glyoxalase I) isomerizes the hemithioacetal formed between @entity2041 and @entity14625 . Unlike other @entity23909 enzymes, @entity526 @entity23909 exhibits no activity with @entity8862 but maximal activation with @entity3411 . To elucidate further the metal site in @entity526 @entity23909 , several approaches were undertaken. Kinetic studies indicate that the catalytic metal ion affects the k (cat) without significantly affecting the K (m) for the substrate. Inductively coupled plasma analysis and isothermal titration calorimetry confirmed one metal ion bound to the enzyme, including @entity8862 , which produces an inactive enzyme. Isothermal titration calorimetry was utilized to determine the relative binding affinity of @entity23909 for various bivalent metals. Each metal ion examined bound very tightly to @entity23909 with an association constant ( K (a))>10(7) M(-1), with the exception of @entity3281 ( K (a) of the order of 10(6) M(-1)). One of the ligands to the catalytic metal, His(5), was altered to @entity1160 , a side chain found in the @entity8862 -active @entity1 @entity23909 . The affinity of the mutant protein for all bivalent metals was drastically decreased. However, low levels of activity were now observed for @entity8862 -bound @entity23909 . Although this residue has a marked effect on metal binding and activation, it is not the sole factor determining the differential metal activation between the @entity1 and @entity526 @entity23909 enzymes.

Investigation of metal binding and activation of XXXX glyoxalase I: kinetic, thermodynamic and mutagenesis studies.

@entity23909 :: ('2739', 'Gene') :: ['GlxI'] @entity8862 :: ('CHEBI:37256', 'Chemical') :: ['Zn(2+)'] @entity14625 :: ('MESH:D011765', 'Chemical') :: ['methylglyoxal'] @entity1 :: ('9606', 'Species') :: ['Homo sapiens', 'human'] @entity1160 :: ('CHEBI:28300', 'Chemical') :: ['glutamine'] @entity3281 :: ('CHEBI:29035', 'Chemical') :: ['Mn(2+)'] @entity2041 :: ('MESH:D005978', 'Chemical') :: ['glutathione'] @entity3411 :: ('CHEBI:49786', 'Chemical') :: ['Ni(2+)'] @entity526 :: ('562', 'Species') :: ['Escherichia coli', 'E. coli']
@entity526 :: (562,Species) :: ['Escherichia coli']
