Purification and Characterization of Carbon–Phosphorus Bond-Cleavage Enzyme From Glyphosate Degrading Pseudomonas putida T5.

An inducible, carbon-phosphorus bond-cleavage enzyme was purified from cells of Pseudomonas
putida T5 grown on N-phosphonomethyl glycine. The native enzyme had a molecular mass
of approximately 70 kD and upon sodium dodecyl sulfate polyacrylamide gel electrophoresis
(SDS-PAGE), yielded a homogeneous protein band with an apparent molecular mass of
about 70 kD. Activity of purified enzyme was increased by 627-fold compared to the crude
extract and showed pH and temperature optima of approximately 7 and 30�C, respectively.
The purified enzyme had an apparent Km and Vmax of 3.7mM and 6.8mM=min, respectively,
for its sole substrate N-phosphonomethyl glycine. The enzyme was inhibited by phenylmethylsulfonyl
fluoride (PMSF), indicating the presence of serine at the active site. The enzyme was
not inhibited by SDS, suggesting the absence of disulfide linkage in the enzyme. The enzyme
was found to be inhibited by most of the metals studied except Mg2þ. Detergents studied also
inhibited glyphosate acting as a carbon–phosphorus bond-cleavage enzyme. Thus initial
characterization of the purified enzyme suggested that it could be used as a potential candidate
for glyphosate bioremediation.