Properties of methemoglobin reductase and kinetic study of methemoglobin reduction.

F Kuma - Journal of Biological Chemistry, 1981 - ASBMB
A soluble erythrocyte cytochrome b5 was purified as the substrate of methemoglobin
reductase and an electron carrier to methemoglobin. The isoelectric point of this protein was
at pH 4.3, and E0'was-0.010 at pH 7.0.. The Km value of the enzyme for this protein was 1 x
10 (-4) M, and the turnover number (k5) was 3.4 x 10 (4) min-1, with NADH as an electron
donor at pH 7.0. The optimum pH of the enzyme was pH 4.6 for ferricyanide and pH 5.5 for
cytochrome b5, with a shoulder of activity at pH 7 to 9 for both substrates. The rate equation …