Mutation of Lys-120 and Lys-134 drastically reduces the catalytic rate of Cu,Zn superoxide dismutase.
Lys-120 and Lys-134, located at the edge of the active site channel in most Cu,Zn superoxide dismutases, have been suggested to play a major role in steering the anionic substrate towards the catalytic copper ion. In this study, mutants of Xenopus laevis Cu,Zn superoxide dismutase have been engineered, with Lys-120 and Lys-134 changed into leucine and threonine, respectively, and their catalytic properties have been investigated by pulse radiolysis. Results obtained demonstrate that both residues decrease the catalytic rate by about 40%, in partial disagreement with previous brownian dynamics calculations, carried out on bovine Cu,Zn superoxide dismutase.
Polticelli
F
F
MRC, Radiobiology Unit, Chilton, Didcot, Oxon, UK.
Battistoni
A
A
Bottaro
G
G
Carrì
M T
MT
O'Neill
P
P
Desideri
A
A
Rotilio
G
G
D000818:Animals; D001665:Binding Sites; D002384:Catalysis; D003300:Copper; D007700:Kinetics; D008239:Lysine / Q000737:chemistry*; D009154:Mutation / Q000502:physiology*; D009994:Osmolar Concentration; D011675:Pulse Radiolysis; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D013482:Superoxide Dismutase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis
D011993:Recombinant Fusion Proteins; D003300:Copper; D013482:Superoxide Dismutase; D008239:Lysine