TABLE 3.
Specific activities of 2-oxo acid decarboxylation by cell extractsa
Nitrogen source | Specific decarboxylase activity [nmol · min−1 · (mg protein)−1]
|
||||
---|---|---|---|---|---|
Phenylpyruvate (phenylalanine) | α-Ketoisovalerate (valine) | α-Ketoisocaproate (leucine) | α-Ketomethylvalerate (isoleucine) | 3-Methylthio α-ketobutyrate (methionine) | |
Ammonia | BDb | BD | BD | BD | BD |
Leucine | 13.5 ± 0.7 (100) | 4 ± 0.01 (29) | 6.5 ± 0.7 (48) | 4.5 ± 0.7 (33) | 5.5 ± 0.6 (41) |
Methionine | 22.25 ± 1.8 (100) | 8.5 ± 0.5 (38) | 9.25 ± 0.5 (42) | 5.5 ± 0.9 (25) | 9 ± 0.01 (40) |
Phenylalanine | 67.5 ± 0.7 (100) | 19 ± 0 (28) | 29.5 ± 0.7 (43) | 25.7 ± 3.8 (38) | 22 ± 0 (32) |
Proline | BD | BD | BD | BD | BD |
Asparagine | BD | BD | BD | BD | BD |
Prepared from aerobic, glucose-limited chemostat cultures of S. cerevisiae CEN.PK 113-7D grown with different amino acids as the sole nitrogen source. Data are the average ± mean deviation of assays from two independent chemostat cultures. The relative 2-oxo acid activities, expressed as a percentage of phenylpyruvate activity, are in parentheses. The column headings include in parentheses the amino acid which the 2-oxo acid used as a substrate is derived from.
BD, below detection limit.