Table 3.

N-Substituted D-Alanines as Substrates^a

Name	Structure	KM,app (mM)	VM,app (s−1)	(V/K)app (M−1 s−1)	$\frac{{(\text{V}/\text{K})}_{\text{app},\text{Gly}}}{{(\text{V}/\text{K})}_{\text{app},\text{D}-\text{Ala}}}$
Acetyl-D-alanine (51)	R = CH3	1400 ± 160	1.3 ± 0.1	0.95 ± 0.05	900
Benzoyl-D-alanine (52)	R = C6H5	84 ± 23	0.27 ± 0.03	3.2 ± 0.6	1,900
CBZ-D-alanine (53)	R = C6H5CH2O	35 ± 5.0	1.4 ± 0.1	41 ± 5	370
N-dansyl-Tyr-Val-D-Alab,c (54)	R = Dansyl-Tyr-Val	0.031 ± 0.004	0.91 ± 0.06	(3.0 ± 0.2) × 104	17

^atBOC-D-alanine is a substrate with a low V/K. At 800 mM tBOC-D-alanine, we obtained a rate of O₂ consumption of 0.63 s⁻¹, which is approximately equal to the rate of O₂ consumption obtained at 15 mM CBZ-D-alanine.

^bKinetics of N-dansyl-Tyr-Val-(D)-Ala amidation were compared directly to N-dansyl-Tyr-Val-Gly amidation, using the exact same reaction conditions and source of PAM. The steady-state kinetic parameters for N-dansyl-Tyr-Val-Gly for this experiment were: K_M,app = 2.7 ± 0.4 μM, V_M,app = 1.4 ± 0.6 s⁻¹, and (V/K)_app = (5.0 ± 0.7) × 10⁵ M⁻¹ s⁻¹.

^cSubstrate inhibition was observed for this compound, K_i = 470 ± 90 μM.