Aromatic metabolism inRhizobium trifolii—protocatechuate 3,4-dioxygenase

✍ Scribed by Y. P. Chen; M. J. Dilworth; A. R. Glenn

• Book ID: 104758510
• Publisher: Springer
• Year: 1984
• Tongue: English
• Weight: 390 KB
• Volume: 138
• Category: Article
• ISSN: 0302-8933
• DOI: 10.1007/bf00402117

✦ Synopsis

Protocatechuate 3,

.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 ~4~4 composition. The enzyme is specific for protocatechuate, with a Km of 1.75 x 10 -5 M and maximum activity at pH 9.2. Metal removal and replacement studies indicate that the enzyme contains complexed Fe 3+ which is required for activity. Direct atomic absorption analysis gave 1.3 -1.5 g atoms Fe 3 + per mole of isolated enzyme, but correction for metal-deficient proteins suggests that the value is close to 2.