W. De Jesus-bonilla et al., Formation of compound I and compound II ferryl species in the reaction of hemoglobin I from Lucina pectinata with hydrogen peroxide, ARCH BIOCH, 390(2), 2001, pp. 304-308
The formation of ferryl heme (Fe(IV) = 0) species, i.e., compound I and com
pound II, has been identified as the main intermediates in heme protein per
oxidative reactions. We report stopped-flow kinetic measurements which illu
strate that the reaction of hemoglobin I (HbI) from Lucina pectinata with h
ydrogen peroxide produce ferryl intermediates compound I and compound II. C
ompound I appears relatively stable displaying an absorption at 648 nm, The
rate constant value (k'(2)) for the conversion of compound I to compound I
I is 3.0 x 10(-2) s(-1), more than 100 times smaller than that reported for
myoglobin, The rate constant value for the oxidation of the ferric heme (k
'(12) + k'(13)) is 2.0 x 10(2) M-1 s(-1). These values suggest an alternate
route for the formation of compound II (by k',,) avoiding the step from co
mpound P to compound II (k'(2)), In HbI from L, pectinata the stabilization
of compound I is attribute to the unusual collection of amino acids residu
es (Q64, F29, F43, F68) in the heme pocket active site of the protein. (C)
2001 Academic Press.