TABLE 4.
2-Keto acid contents of S. typhimurium and E. coli K-12 strains
| Strain | Mediuma | Intracellular concn (μM) ofb:
|
KIV/KB ratio | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Pyr + PEP (HPLC) | Pyr (LDH) | KB | KIV | KIC | KMV | Glyoxylate | |||
| LT2 | Glc | 1,670 ± 170 | 1,370 ± 130 | 17 ± 4 | 66 ± 16 | 7 ± 1 | 27 ± 4 | 11 ± 1 | 4.0 |
| TV105 | Glc | 1,190 ± 90 | 930 ± 1 | 9 ± 2 | 20 ± 3 | 7 ± 2 | 19 ± 2 | 11 | 2.2 |
| TV105 | Glc + Ile, Val | 1,720 | NM | 22 | 150 | 10 | 113 | NC | 6.8 |
| TV506 | Glc | 1,780 ± 30 | 1,570 ± 130 | 36 ± 9 | 10 ± 4 | 6 ± 1 | 180 ± 60 | NC | 0.3 |
| TV496 | Glc + Pan | 1,215 ± 90 | 890 ± 40 | 62 ± 6 | 17 ± 1 | 1.7 ± 1 | ND | NC | 0.28 |
| TV496 | Glc + Ile | 1,550 ± 300 | 1,040 ± 30 | 17 ± 2 | 8 ± 2 | 2 ± 1 | 93 ± 11 | NC | 1.1 |
| TV497 | Glc + Pan | 1,250 ± 120 | 990 ± 70 | 140 ± 7 | 23 ± 2 | ND | 64 ± 17 | NC | 0.17 |
| TV108 | Glc | 1,095 | 952 | 132 | 64 | 10 | 45 | NC | 0.48 |
| TV108 | Glc + Ile | 2,150 | NM | 6 | 290 | 82 | 340 | NC | 48 |
| MM294 | Glc | 1,370 ± 140 | 820 ± 70 | 28 ± 2 | 58 ± 3 | 8 ± 2 | 8 ± 1 | NC | 2.1 |
| LT2 | Acetate | 1,200 ± 80 | 660 ± 10 | 17 ± 2 | 10 ± 1 | 7 ± 1 | 29 ± 4 | 120 ± 20 | 0.6 |
| TV105 | Acetate | 730 | 720 | 3 | 1.7 | ND | 1.8 | 47 | 0.5 |
| TV496 | Acetate | 880 ± 70 | 770 ± 20 | 23 ± 2 | 6 ± 1 | ND | 11 ± 2 | 100 ± 10 | 0.26 |
| MM294 | Acetate | 650 | 400 | 16 | 7 | ND | 18 | NC | 0.44 |
Bacterial cultures were grown in glucose (Glc) or acetate. Additions to the media were as follows: Pan, 0.34 mM pantothenate; Ile, 0.38 mM isoleucine; and Val, 0.76 mM valine. Extracts were prepared as described in Materials and Methods.
Except for pyruvate (Pyr), all keto acids were determined by high-pressure liquid chromatography (HPLC) with precolumn derivatization with 1,2-diamino-4,5-methylenedioxybenzene as described in Materials and Methods. Pyr was determined by a spectrophotometric method with lactate dehydrogenase (LDH) as described previously (25). Concentrations were calculated assuming the intracellular volume as described in the text. PEP, phosphoenolpyruvate; KB, 2-ketobutyrate; KIV, 2-ketoisovalerate; KIC, 2-keto-4-methylvalerate (ketoisocaproate); KMV, 2-keto-3-methylvalerate. NM, not measured (the enzyme-coupled assay was not performed); ND, not detected (≤1 μM); NC, not calculated (the determination of glyoxylate required collection and analysis of early data from the HPLC run, which was not always carried out).