L. Banci et al., SYNTHESIS AND CHARACTERIZATION OF A MONOMERIC MUTANT CU ZN SUPEROXIDE-DISMUTASE WITH PARTIALLY RECONSTITUTED ENZYMATIC-ACTIVITY/, European journal of biochemistry, 234(3), 1995, pp. 855-860
A monomeric analog of human Cu/Zn superoxide dismutase (F50E/G51E SOD)
, previously characterized and found to have reduced enzymic activity,
was here further modified by replacing Glu133 with Gin. This substitu
tion does not dramatically affect the coordination geometry at the act
ive site, but enhances enzymic activity, and also increases the affini
ty for anions at the active site. This behavior parallels earlier publ
ished results in which this point mutation was made in the dimeric wil
d-type enzyme. The analog described here has afforded for the first ti
me a monomeric superoxide dismutase with substantial activity. This po
int mutation does not significantly influence the protein structure bu
t interactions with anions, including superoxide, are altered with res
pect to the monomeric form. The present monomeric Glu133Gln mutant has
partially restored enzymic activity. The diminished activity of the m
onomeric analogs is discussed in the light of possible minor structura
l changes and some of their characteristics are compared with those of
naturally occurring mutants associated with various neurological dise
ases.