TY  - JOUR
PY  - 1990//
TI  - A kinetic study on the suicide inactivation of peroxidase by hydrogen peroxide
JO  - Biochimica et biophysica acta
A1  - Arnao, M. B.
A1  - Acosta, M.
A1  - del Río, J. A.
A1  - Varon, R.
A1  - García-Cánovas, F.
SP  - 43
EP  - 47
VL  - 1041
IS  - 1
N2  - In the absence of reductant substrates, and with excess H2O2, peroxidase (donor: hydrogen-peroxide oxidoreductase, EC 1.11.1.7) shows the kinetic behaviour of a suicide inactivation, H2O2 being the suicide substrate. From the complex (compound I-H2O2), a competition is established between two catalytic pathways (the catalase pathway and the compound III-forming pathway), and the suicide inactivation pathway (formation of inactive enzyme). A kinetic analysis of this system allows us to obtain a value for the inactivation constant, ki = (3.92 +/- 0.06) x 10(-3) x s-1. Two partition ratios (r), defined as the number of turnovers given by one mol of enzyme before its inactivation, can be calculated: (a) one for the catalase pathway, rc = 449 +/- 47; (b) the other for the compound III-forming pathway, rCoIII = 2.00 +/- 0.07. Thus, the catalase activity of the enzyme and, also, the protective role of compound III against an H2O2-dependent peroxidase inactivation are both shown to be important.<p /> <p>Language: en</p>
LA  - en
SN  - 0006-3002
UR  - http://dx.doi.org/10.1016/0167-4838(90)90120-5
ID  - ref1
ER  -