Table 1.
IMPDH |
kcat (s−1) |
Km IMP (μM) |
Km NAD+ (μM) |
Kii NAD+ (mM) |
Ki MPA (nM) |
---|---|---|---|---|---|
Human type I | 1.2-1.8a | 14-18a | 42-70a | 2.0b | 11-33c |
Human type II | 0.4-1.4d | 4-9d | 6-32d | 0.59e | 7-14f |
Aerobacter aerogenes t | n.d. | 60 | 800 | n.d. | n.d. |
Borellia burgdorferi g | 2.6 | 30 | 1100 | 2.3 | 8,000 |
Cryptosporidium parvum h | 3.3 | 29 | 150 | 2.9 | 9,300 |
Escherichia coli | 13i | 61i | 2000i | 2.8i | ~20,000j |
Helicobacter pylori k | 3.0 | 18 | 73 | 1.7 | n.d. |
Mycobacterium tuberculosis l | 0.53 | 78 | 1000 | 5.0 | 62,000 |
Streptococcus pyogenes m | 24 | 62 | 1180 | n.d. | >10,000 |
Tritrichomonas foetus n | 1.9g | 1.7g | 150g | 6.8g | 9,000g |
n.d., no data. Assay buffers are generally similar, but temperature varies between 25-37 degrees C. Values of kcat are reported per active site, not per tetramer. Note that while C. parvum and T. foetus are protozoan parasites, their IMPDHs are most similar bacterial enzymes, suggesting that the genes where obtained by horizontal transfer.
[82];
[83];
[85];
[66];
[86];
N. Benfield and L. Hedstrom, unpublished data;
[24];
[62];
[78];
[87].