Table 2.

Inhibition of PchP by AACs. Percentage inhibition was measured with 1 mM inhibitor, 10 mM p-NPP, and 2 mM Mg²⁺ at pH 5.0. Inhibition constants were calculated with the application of the program DYNAFIT from activity curves performed in the presence of 0.5, 1, 2, 4, and 10 mM p-NPP with 2 mM Mg²⁺ in 100 mM sodium acetate buffer, pH 5.0. The AAC concentrations were 0.01, 0.05, 0.25, and 1 mM. Values shown are averaged from three independent experiments ± SD. PU: partial uncompetitive and C: competitive inhibition.

Inhibitor	Number of N-alkyl groups	% Inhibition	Inhibition constants		Type of inhibition
			KI1, mM ± SD	KI2, mM ± SD
Trimethylamine	N,N,N-trimethyl	81	0.21 ± 0.03	0.06 ± 0.01	PU + C
Tetramethylammonium	N,N,N,N-tetramethyl	91	0.17 ± 0.04	0.04 ± 0.01	PU + C
Choline	1 N,N,N-trimethyl	85	0.89 ± 0.08	0.10 ± 0.01	PU + C
Chlorocholine	1 N,N,N-trimethyl	82	0.44 ± 0.04	0.12 ± 0.01	PU + C
Betaine	1 N,N,N-trimethyl	26	1.44 ± 0.09	7.75 ± 0.91	PU + C
Hexamethonium	2 N,N,N-trimethyl	85	0.37 ± 0.05	0.08 ± 0.01	PU + C
Decamethonium	2 N,N,N-trimethyl	83	0.21 ± 0.04	0.08 ± 0.01	PU + C
Tubocurarine	1 N-methyl + 1 N,N-dimethyl	22	2.51 ± 0.21	4.10 ± 1.20	PU + C
Neostigmine	1 N,N-dimethyl + 1 N,N,N-trimethyl	55	6.25 ± 0.34	0.57 ± 0.05	PU + C
2-amino-2-methyl-1-propanol	1 N	74	3.94 ± 0.16	0.21 ± 0.01	PU + C
L-histidinol	1 N	56	2.11 ± 0.05	0.31 ± 0.08	PU + C