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. Author manuscript; available in PMC: 2019 Dec 26.
Published in final edited form as: Biochemistry. 2018 Dec 12;57(51):7011–7020. doi: 10.1021/acs.biochem.8b00946

Table 2.

Comparison of Kinetic Parameters for Tagged and Cleaved PA3944 Enzyme

PA3944 enzyme substrate KM (mM) kcat(s−1) kcat/KM(M−1 s−1)
tagged polymyxin B (constant [AcCoA])a 2.57 ± 0.23 0.653 2.54 × 102
colistin (constant [AcCoA])a 2.28 ± 0.17 0.672 2.95 × 102
DAB (constant [AcCoA])a,b 8.60 ± 1.59 0.264 30.7 × 10
AcCoA (constant [polymyxin B])c 0.118 ± 0.028 0.602 5.10 × 103
AcCoA (constant [colistin])c 0.105 ± 0.017 0.471 4.49 × 103
cleaved polymyxin B (constant [AcCoA])a 4.00 ± 0.32 0.923 3.65 × 102
colistin (constant [AcCoA])a 2.50 ± 0.13 0.894 3.58 × 102
DAB (constant [AcCoA])a,b 10.0 ± 1.2 0.391 3.91 × 10
AcCoA (constant [polymyxin B])c 0.137 ± 0.020 0.610 4.45 × 103
AcCoA (constant [colistin] )c 0.118 ± 0.021 0.456 3.86 × 103
a

The concentration of AcCoA was held constant at 0.5 mM while that of the acceptor substrate(s) was varied.

b

At DAB concentrations of >10 mM, substrate inhibition was observed; therefore, kinetic parameters were calculated on the basis of data collected from 0 to 10 mM DAB.

c

The concentration of polymyxin B or colistin was held constant at 5 mM while that of AcCoA was varied.