Table 3.
Propertya | rRgpAH | RgpB | rKgp | |
---|---|---|---|---|
Plus glycylglycineb with 5 nM enzyme | Km (µM) | 72 ± 3.5 | 52 ± 2.3 | 202 ± 18 |
Vmax (nM s−1) | 202 ± 2 | 70 ± 0.5 | 113 ± 3.5 | |
kcat s−1 | 40.4 ± 0.3 | 14 ± 0.1 | 22.6 ± 0.7 | |
kcat/Km (s−1 M−1) | 5.6 × 105 | 2.7 × 105 | 1.1 × 105 | |
No glycylglycine With 1 nM enzyme | Km (µM) | 13.5 ± 1.5 | 10.2 ± 1.1 | 39 ± 2.4 |
Vmax (nM s−1) | 7.0 ± 0.1 | 7.4 ± 0.1 | 5.4 ± 0.04 | |
kcat (s−1) | 7.0 ± 0.7 | 7.4 ± 0.1 | 5.4 ± 0.04 | |
kcat/Km (s−1 M−1) | 5.1 × 105 | 7.2 × 105 | 1.4 × 105 |
aIn the absence of active site titration confirming enzyme concentration kcat is presumptive and assumes all enzyme molecules applied to the assay are active. Enzyme concentrations are based upon absorbance at 280 nm wavelength and extinctions coefficients assuming all cysteine are reduced. Extinction coefficient (M−1 cm−1): rRgpAH 48360, RgpB 49850, Kgp 105090.
bGlycylglycine was 300 mM in the rRgpAH and RgpB assays and 180 mM in the rKgp assay.