Partial purification and some properties of β-phosphoglucomutase from Lactobacillus brevis
A phosphoglucomutase (β-phosphoglucomutase) specific for β-glucose 1-phosphate, which catalyzes the β-glucose 1-phosphate:glucose 6-phosphate interconversion, was 560-fold purified from Lactobacillus brevis strain L 6. The isoelectric point of β-phosphoglucomutase was 3.8 and it had an apparent mole...
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Published in | Archives of biochemistry and biophysics Vol. 228; no. 2; pp. 592 - 599 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
United States
Elsevier Inc
01.02.1984
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Subjects | |
Online Access | Get full text |
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Summary: | A phosphoglucomutase (β-phosphoglucomutase) specific for β-glucose 1-phosphate, which catalyzes the β-glucose 1-phosphate:glucose 6-phosphate interconversion, was 560-fold purified from
Lactobacillus brevis strain L
6. The isoelectric point of β-phosphoglucomutase was 3.8 and it had an apparent molecular weight of 29,000 estimated by gel chromatography. The enzyme required a divalent cation (Mn
2+ > Mg
2+ > Ni
2+ > Co
2+) and β-glucose 1,6-bisphosphate for activity. The equilibrium constant
K
e
for the reaction β-
d-glucose 1-phosphate γ
d-glucose 6-phosphate at 30 °C and pH 6.7 is 18.5. β-phosphoglucomutase had a pH optimum between 6.3 and 6.8 and appeared to be quite specific: α-glucose 1-phosphate, α- or β-galactose 1-phosphate and α- or β-
N-acetylglucosamine 1-phosphate did not substitute for β-glucose 1-phosphate. Double reciprocal plots of the data from initial velocity studies at five β-glucose 1-phosphate concentrations (10 to 100 μ
m) and four β-glucose 1,6-bisphosphate concentrations (0.125 to 1.0 μ
m) showed that the apparent Michaelis constants for β-glucose 1-phosphate and β-glucose 1,6-bisphosphate were related to the concentrations of β-glucose 1,6-bisphosphate and β-glucose 1-phosphate, respectively, in such a way as to suggest a pingpong mechanism. The same conclusion was obtained when substrate-velocity relationships were investigated at fixed ratio of both substrates: the Lineweaver-Burk plots showed linear lines and no parabolic ones. The “true”
K
m
for β-glucose 1-phosphate and β-glucose 1,6-bisphosphate were found to be about 12 and 0.8 μ
m, respectively. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0003-9861 1096-0384 |
DOI: | 10.1016/0003-9861(84)90027-4 |