Partial Purification and Characterization of the Gibberellin A(20) 3beta-Hydroxylase from Seeds of Phaseolus vulgaris.

The GA(20) 3beta-hydroxylase present in immature seeds of Phaseolus vulgaris has been partially purified and characterized. The physical characteristics of the enzyme are similar to those of the GA 2beta-hydroxylases present in mature and immature seeds of Pisum sativum. It is acid-labile, hydrophobic, and of M(r) 45,000. The enzyme catalyzes the synthesis of GA(1), GA(5), and GA(29) from GA(20). Activity is dependent upon the presence of Fe(2+), ascorbate, 2-oxoglutarate, and oxygen. 2-Oxoglutarate does not function as a cosubstrate; in the presence of the enzyme, succinate is not a reaction product.