Yd. Ivanov et al., Optical biosensor studies on the productive complex formation between the components of cytochrome p450scc dependent monooxygenase system, BIOC MOL B, 47(2), 1999, pp. 327-336
The formation of individual complexes between the components of cholesterol
side chain cleavage system - cytochrome P450scc, adrenodoxin (Ad) and adre
nodoxin reductase (AdR) was kinetically characterized and their association
and dissociation rate constants were measured by optical biosensor. The do
minant role of interprotein electrostatic interactions in productive comple
x formation was demonstrated. Despite of the fact that P450scc and AdR comp
ete for the binding with the same or closely placed negatively charged grou
ps on the surface of immobilized Ad, the formation of the AdR/P450scc/Ad te
rnary complex upon AdR immobilization on dextran was registered. It is show
n, that Ad does not bind to AdR immobilized via amino groups AdR(im) but it
is possible only after the preliminary binding of P450scc to AdR(im). The
life time of such ternary complex, about 15 s, is sufficient for the realiz
ation of 5-8 catalytic cycles.