TABLE 3.

Comparison of the cell wall channel properties of R. equi, R. erythropolis, C. glutamicum, N. farcinica, N. corynebacteroides (R. corynebacteroides) and M. bovis BCG

Cell wall porin of indicated species	G (nS) in 1 M KCl	Selectivity (Pc/Pa)a in KCl	Point charges at the channel mouth	Channel diameter (nm) by ion radiusb	Channel diameter (nm) by negative point chargec	Reference or source
R. equi
PorAReq	4.00	9.0	−1.5	1.8	2.0	This study
PorBReq	0.30	0.16	+1.5	1.4	1.4
R. erythropolis	6.00	11.80	−2.7	2.0	2.0	22
C. glutamicum PorA	5.50	8.10	−2.0	2.2	2.2	20
N. corynebacteroides (R. corynebacteroides)	5.50	3.80	−2.7	2.0	2.2	37
N. farcinica	3.0	8.2	−1.3	1.4	1.6	40
M. bovis BCG						21
PorAMbo	4.30	>1	NDd	ND	ND
PorBMbo	0.78	<1	ND	ND	ND

^aP_c/P_a, P_cation/P_anion.

^bEstimated from the single-channel conductance as a function of the hydrated ion radii.

^cEstimated from the effect of negative point charges on single-channel conductance.

^dND, not done.