Table 2.

Factors that decrease the excitation energy of (bacterio)chlorophyll [(B)Chl] in the reaction center in millielectron volts

	BM*	PM*	PL*	BL*	ChlD2*	PD2*	PD1*	ChlD1*
(B)Chl* in vacuum	1,834	1,834	1,834	1,834	2,129	2,129	2,129	2,129
+Ring deformation†	−45	−48	−50	−67	−32	−3	−26	−37
+Protein electrostatics‡	−83	−70	−109	−64	−62	−38	−39	−85
(B)Chl* in protein without special pair formation	1,706	1,716	1,675	1,703	2,041	2,088	2,064	2,012
+Special pair formation§	0	−271	−230	0	0	0	0	0
(B)Chl* in protein	1,706	1,445	1,445	1,703	2,041	2,088	2,064	2,012

^†Influence of deformation of the chlorin ring due to interactions with the protein environment (e.g., van der Waals contact and H-bond interactions).

^‡Influence of electrostatic interactions with the protein environment.

^§Influence of the formation of the special pair.