Table 4.

E_ox/sq and pK_a(N5) in mV and pK_a units, respectively. E_ox/sq are discussed in “Calculated values of E_ox/sq in XDH and XO”.

		XDH		XO
		Em	pKa	Em	pKa
Eox/sq (= Em(FAD/FAD−) + RT/F ln10 log(1+10 − (pH − pKa(N5))) c	experimental	−270a		−332b
	calculated	−296		−322
	uncharged protein d	−298		−301
	reference (water) e	−238		−238
Eox/sq shift (from water to protein)	Total	−14		−40
	ΔEm(charge) g	1		−21
	ΔEm (dielectric volume) h	−16		−19
a) Em (FAD/FAD−)	experimental	n.d. f		n.d. f
	calculated	−550		−429
	uncharged protein d	−520		−502
	reference (water) e	−333		−333
Em shift (from water to protein)	Total	−217		−96
	ΔEm(charge) g	−30		73
	ΔEm (dielectric volume) h	−187		−169
b) pKa(N5) for FADH•/FAD•−	experimental		n.d.		n.d.
	calculated		12.1		9.6
	uncharged protein d		11.6		11.2
	reference (water) e		8.6		8.6
pKa shift (from water to protein)	Total		3.5		1.0
	ΔpKa(charge) g		0.5		−1.6
	ΔpKa(dielectric volume) h		3.0		2.6
b′) corresponding Em term i.e., RT/F ln10 log(1+10− (pH − pKa(N5)))	experimental	n.d. f		n.d. f
	calculated	254		107
	uncharged protein d	222		201
	reference (water) e	51		51
Em shift (from water to protein)	Total	203		56
	ΔEm(charge) g	31		−94
	ΔEm (dielectric volume) h	171		150

^aAt pH 7.5 ³.

^bAt pH 7.7 ⁴.

^cSee Ref. ¹².

^dPrepared by setting atomic charges of all atoms in the protein to zero.

^eSee Ref. ³¹.

^fNot determined.

^gInfluence of atomic charge of all atoms in the protein.

^hInfluence of uncharged protein dielectric volume (i.e., the space covered by the merged van der Waals volumes of protein atoms).