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Carbamoylation of Cu,Zn‐superoxide dismutase by cyanate
Author(s) -
Cocco Dina,
Rossi Luisa,
Barra Donatella,
Bossa Francesco,
Rotilio Giuseppe
Publication year - 1982
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(82)80756-4
Subject(s) - superoxide dismutase , chemistry , electron paramagnetic resonance , ionic strength , enzyme , cyanate , covalent bond , ionic bonding , active site , superoxide , enzyme assay , biochemistry , ion , polymer chemistry , organic chemistry , nuclear magnetic resonance , physics , aqueous solution
Reaction with cyanate leads to a reversible change of the EPR spectrum of Cu,Zn‐superoxide dismutase and to time‐dependent carbamoylation of the lysine residues of the enzyme, producing a stable covalent derivative with more negative charge. The carbamoylated enzyme is less active than the native enzyme in spite of unaltered EPR spectra. The extent of this inactivation is much less when the enzyme activity is measured at low ionic strength. These results show that integrity of the active site is not the sole factor playing a role in the enzyme mechanism and that the ionic strength effect is related to electrostatic interactions between O − 2 and surface charges of the protein.