ISSN:
1432-072X
Keywords:
Rhizobium
;
Aromatic metabolism in protocatechuate 3,4-dioxygenase
;
R. trifolii
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Protocatechuate 3,4-dioxygenase (EC 1.13.11.3) has been purified 42-fold from 4-hydroxybenzoate-grown cells of Rhizobium trifolii TA1, where it constitutes about 2% of the cell protein. The dioxygenase has a molecular weight of 220,000, with two dissimilar sub-units of molecular weights 29,000 and 26,500, corresponding to an α4β4 composition. The enzyme is specific for protocatechuate, with a Km of 1.75×10-5 M and maximum activity at pH 9.2. Metal removal and replacement studies indicate that the enzyme contains complexed Fe3+ which is required for activity. Direct atomic absorption analysis gave 1.3–1.5 g atoms Fe3+ per mole of isolated enzyme, but correction for metal-deficient proteins suggests that the value is close to 2.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00402117
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