Characterization of ascorbate oxidase from Acremonium sp. HI-25.
The ascorbate oxidase obtained from a microorganism, Acremonium sp. HI-25 (molecular weight, 80 kDa; monomeric protein), was studied with respect to atomic absorption, EPR, absorption spectra, circular dichroism (CD) spectra, and steady-state kinetics. The enzyme was found to be a multicopper protein, containing four copper atoms of three kinds, types 1, 2, and 3 copper, in the ratio of 1:1:2. The EPR parameters of the type 1 and 2 copper atoms in the ascorbate oxidase are very similar to those in the case of the ascorbate oxidase obtained from cucumber, which is a dimeric protein. The apparent Km and kcat values for ascorbic acid of the ascorbate oxidase from Acremonium sp. HI-25 are almost the same as those of the monomeric unit of the ascorbate oxidase from cucumber.
Hirose
J
J
Department of Food Science and Technology, Faculty of Engineering, Fukuyama University, Hiroshima.
Sakurai
T
T
Imamura
K
K
Watanabe
H
H
Iwamoto
H
H
Hiromi
K
K
Itoh
H
H
Shin
T
T
Murao
S
S
D000164:Acremonium / Q000201:enzymology*; D001204:Ascorbate Oxidase / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D018553:Cucumis sativus / Q000201:enzymology
D003300:Copper; D001204:Ascorbate Oxidase