ACC deaminase activity was assayed according to a modified
method of [22,23] which measures the amount of α-ketobutyrate
produced upon the hydrolysis of ACC. The number of μmol of
α-ketobutyrate produced by this reaction was determined by
comparing the absorbance at 540 nm of a sample to a standard
curve of α-ketobutyrate ranging between 10 and 200 μmoL. A stock
solution of 100 mmoL L-1 α-ketobutyrate was prepared in
0.1 moL L-1 of Tris–HCl, (pH 8.5) and stored at 4°C. Just prior to use,
the stock solution was diluted with the same buffer to make
10 mmoL L-1 of solution from which a standard concentrations
curve was generated.