Skip to main content

View full-text article in PMC

. Author manuscript; available in PMC: 2012 Jul 1.

Published in final edited form as: Med Res Rev. 2010 Feb 4;31(4):483–519. doi: 10.1002/med.20187

Table IV.

Uptake and Inhibition Kinetic Parameters of MPTP and MPP⁺ Derivatives for Bovine Chromaffin Granule VMAT.^a


	Inhibitor/Substrate	K_i (μM)^a	K_m (μM)^b	V_max (nmols/mg.min)^b	K_m,_DA/K_i^c
MPP⁺ Derivatives
15	MPP⁺I⁻	92 ± 14	73 ± 11	1.4 ± 0.1	0.3
38	2′-MeMPP⁺I⁻	95 ± 10			0.3
39	3′-OHMPP⁺I⁻	2.4 ± 0.1	8.4 ± 2.1	1.9 ± 0.1	9.7
40	4′-OHMPP⁺I⁻	82 ± 11	107 ± 16	1.6 ± 0.1	0.7
41	4′-OMeMPP⁺I⁻	106 ± 14^d	135 ± 9	1.6 ± 0.1	0.2
42	3-Me 4-‘OHMPP⁺I⁻	65 ± 19^d			0.8
43	4′-FMPP⁺I⁻	51.3 ± 6.3^d			1.0
44	4′-ClMPP⁺I⁻	7.6 ± 0.7			5.8
45	3′-ClMPP⁺I⁻	46.3 ± 5.4^d			1.1
46	4′-CF₃MPP⁺I⁻	33.8 ± 4.2^d			1.3
47	3′-CF₃MPP⁺I⁻	24.6 ± 3.0^d			1.8
48	4′-CH₃MPP⁺I⁻	51.8 ± 8.7	41.3 ± 6.6	0.9 ± 0.1	1.0
49	4′-OHN3PP⁺I⁻	338 ± 142			0.1
50	3′-OHN3PP⁺I⁻	36.6 ± 4.3^d			1.2
MPTP Derivatives
51	MPTPHCl	52.5 ± 6.3	409 ± 88	1.7 ± 0.3	0.5
52	2′-MeMPTPHCl	38.4 ± 5.2			0.7
53	2′-NH₂MPTPHCl	193 ± 39^d			0.1
54	3′-OHMPTP HCl	25.8 ± 3.1^d			1.7
55	4′-OHMPTP HCl)	134 ± 24^d			0.3
56	3′-ClMPTP HCl	27.7 ± 3.4			1.6
57	4′-F MPTP HCl	49.7 ± 6.3^d			0.9
58	MPDP⁺ClO4⁻	53.0 ± 13.6^d			0.7

^a

Determined with resealed granule ghosts using DA as the substrate in the presence of 10 mM ATP, at pH 7.2.

^b

Determined from initial rate uptake data under the same conditions;

^c

Included for comparison purposes.

^d

Estimated from a set of single inhibitor concentration data set (for further details see ref. ⁵⁵).