468
VERNON H. CHELDELIN, CHIH H. WANG, AND TSOO E. KING
molecular oxygen is involved, the standard free energy change for Reaction it must be about —30 kcal.; for the over-all oxidation from
glucose to gluconic acid and hydrogen peroxide it would be —33.6 kcal.
It is truly an exergonic reaction. However, it is not certain whether
the reaction even in vivo can be coupled with other reactions so that
the energy given can be functionally conserved into ATP.
In general both the oxidase and the dehydrogenase catalyze the
oxidation of nonphosphorylated sugars. Although they occur widely in
microbial phyla, they do not appear to play as important a role in
metabolism as enzymes in other well-known cycles. It would be fair to
say, however, that the apparent lack of importance may be due to the
deficiency in understanding these systems.
Müller (223-225) as early as 1928 described a glucose oxidase in
Aspergillus niger and Penicillium glaucum. Later an apparently similar
enzyme was found in other species of Aspergillus (226) and in Fusarium
lint (227). However, Müller (228) as well as Ogura (229) has claimed
that two different enzymes exist in mold. One reacts with oxygen and
the other does not. Müller's preparations catalyze the oxidation of
glucose by molecular oxygen, and are cyanide insensitive. Their specific
activities are actually very low. Franke and co-workers (230, 231) have
been able to purify the enzyme further. They have found hydrogen
peroxide as a product and a flavin as the coenzyme. Using the preparation with Q 02 value of 8000 at 30°, Franke (232) has challenged the
claim made by Müller and by Ogura as far as A. oryzae, A. niger, and
P. glaucum are concerned.
In the early 1940's an English group energetically worked on an
antibiotic, notatin (226, 233). They prepared samples of about 90%
purity as measured by electrophoresis and ultracentrifugation. Using
this sample Keilin and Hartree (234) have conclusively resolved the
dispute between Müller and Franke. Samples with Q Ö2 values as high
as 30,000 react also effectively with 2,6-dichlorophenol indophenol. At
the same time the identity of the glucose oxidase of Müller and Franke,
notatin of Raistrick et al., and penicillin B of van Bruggen et al. (235)
has been definitely proved.
The absorption maxima of notatin, according to Keilin and Hartree,
are at 377 and 455 m/A whereas those of penicillin B are at 375 and
452 τημ. The difference is evidently due to the difference in operation.
From the flavin content the molecular weight of the enzyme is calculated at 83,000 (234), but that derived from physical determinations
is 152,000 (236). It is suggested that each enzyme contains two prosthetic groups. The flavin can replace the coenzyme of D-amino acid
oxidase, and thus it is flavin adenine dinucleotide. It is interesting to
VERNON H. CHELDELIN, CHIH H. WANG, AND TSOO E. KING
molecular oxygen is involved, the standard free energy change for Reaction it must be about —30 kcal.; for the over-all oxidation from
glucose to gluconic acid and hydrogen peroxide it would be —33.6 kcal.
It is truly an exergonic reaction. However, it is not certain whether
the reaction even in vivo can be coupled with other reactions so that
the energy given can be functionally conserved into ATP.
In general both the oxidase and the dehydrogenase catalyze the
oxidation of nonphosphorylated sugars. Although they occur widely in
microbial phyla, they do not appear to play as important a role in
metabolism as enzymes in other well-known cycles. It would be fair to
say, however, that the apparent lack of importance may be due to the
deficiency in understanding these systems.
Müller (223-225) as early as 1928 described a glucose oxidase in
Aspergillus niger and Penicillium glaucum. Later an apparently similar
enzyme was found in other species of Aspergillus (226) and in Fusarium
lint (227). However, Müller (228) as well as Ogura (229) has claimed
that two different enzymes exist in mold. One reacts with oxygen and
the other does not. Müller's preparations catalyze the oxidation of
glucose by molecular oxygen, and are cyanide insensitive. Their specific
activities are actually very low. Franke and co-workers (230, 231) have
been able to purify the enzyme further. They have found hydrogen
peroxide as a product and a flavin as the coenzyme. Using the preparation with Q 02 value of 8000 at 30°, Franke (232) has challenged the
claim made by Müller and by Ogura as far as A. oryzae, A. niger, and
P. glaucum are concerned.
In the early 1940's an English group energetically worked on an
antibiotic, notatin (226, 233). They prepared samples of about 90%
purity as measured by electrophoresis and ultracentrifugation. Using
this sample Keilin and Hartree (234) have conclusively resolved the
dispute between Müller and Franke. Samples with Q Ö2 values as high
as 30,000 react also effectively with 2,6-dichlorophenol indophenol. At
the same time the identity of the glucose oxidase of Müller and Franke,
notatin of Raistrick et al., and penicillin B of van Bruggen et al. (235)
has been definitely proved.
The absorption maxima of notatin, according to Keilin and Hartree,
are at 377 and 455 m/A whereas those of penicillin B are at 375 and
452 τημ. The difference is evidently due to the difference in operation.
From the flavin content the molecular weight of the enzyme is calculated at 83,000 (234), but that derived from physical determinations
is 152,000 (236). It is suggested that each enzyme contains two prosthetic groups. The flavin can replace the coenzyme of D-amino acid
oxidase, and thus it is flavin adenine dinucleotide. It is interesting to