PURIFICATION AND CHARACTERIZATION OF A NITRILASE FROM BRASSICA-NAPUS

In germinating seedlings of Brassica napus glucosinolate levels decrea se and are potentially degraded to nitriles by a myrosinase. Little is known about the metabolism of glucosinolate aglycone products and the objective of this work was to investigate nitrilase activity and carr y out a purification of the enzyme from seedlings of B. napus. A nitri lase capable of converting phenylpropionitrile to phenylpropionic acid was purified to apparent homogeneity from seedlings of B. napus. The protein has a molecular mass of approximately 420 kDa made up of 38 kD a subunits. The pI of the native protein was found to be 4.6. Under de naturing conditions on an isoelectric focusing (IEF) gel a major and m inor protein was observed with pI in the range of 5.4-5.9, suggesting the presence of isoforms. Apart from the potential role of the nitrila se in indole-3-acetic acid (IAA) synthesis a developmental study with seedlings indicates that the increase in activity observed map be link ed to the in vivo degradation of glucosinolates.