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. Author manuscript; available in PMC: 2021 May 26.
Published in final edited form as: Bioconjug Chem. 2020 May 27;31(6):1624–1634. doi: 10.1021/acs.bioconjchem.0c00163

Table 1:

Kinetics of CdSrtA catalyzed lysine-isopeptide formation

kcat × 10−5 (s−1)a NKM × 10−4 (M) SKM × 10−4 (M) kcat/ NKM (s−1 M−1)
CdSrtA n.d.b n.d. n.d. n.d.
CdSrtA3M 5.6 ± 0.8 0.7 ± 0.1 20 ± 10 0.7 ± 0.1
 H160A 3.1 ± 0.4 0.43 ± 0.05 ----- 0.72 ± 0.08
 C222A n.d. n.d. ----- n.d.
 R231A n.d. n.d. ----- n.d.
CdSrtAΔ 40 ± 0.1 1.6 ± 0.4 16 ± 3 2.5 ± 0.6
 H160A 2.5 ± 0.6 0.70 ± 0.02 ----- 0.36 ± 0.09
 C222A n.d. n.d. ----- n.d.
 R231A n.d. n.d. ----- n.d.
SaSrtAc 1600 ± 100 1.8 ± 0.1 73.3 ± 10.1d 86 ± 5

All kinetics are approximations as saturating concentrations were not able to be measured

a

Transpeptidation steady-state kinetic parameters for CdSrtA were determine by the monitoring rate at which the enzyme ligated an FELPLTGGSG peptide to the NSpaA domain via a lysine-isopeptide bond..

b

n.d., not determined because insufficient amount of product was detectable.

c

Transpeptidation steady-state kinetic parameters for SaSrtA were determine by monitoring the rate at which the enzyme ligated GGG and FELPLTGGSG peptides via a backbone peptide bond. Reported values are the average from three measurements, and the error is the standard deviation.

d

Values are reported from Frankel et al (2005) and measures reactions between a Abz-LPETG-Dap(Dnp)-NH2 and pentaglycine.28 NRefers to transpeptidation kinetics measure when NSpaA is varied and FELPLTGGSG concentration is held constant. SRefers to when FELPLTGGSG peptide is varied and NSpaA is held constant.