Table 3.

Standard Reduction Potentials E^o of R. prolixus wt NP7 and NP7(Δ1-3) at 27 ± 1 °C in Complex with the Distal Heme Ligand L, in Comparison to the Data Reported for NP1-4.^a

		$E_{\mathrm{c}}^{\mathrm{o}}$ (mV vs. SHE)			$E_{\mathrm{c}}^{\mathrm{o}}-E_{{\mathrm{H}}_2\mathrm{O}}^{\mathrm{o}}$ (mV)
	L =	H2O b	NO	histamine	NO	histamine
NP1	pH 5.5	−274 ± 2 c	+154 ± 5 c	−339 ± 2 d	+428	−65
	pH 7.5	−303 ± 4 c	+127 ± 4 c	−403 ± 1 d	+430	−100
NP2	pH 5.5	−287 ± 5 d	+49 ± 3 d	−410 ± 3 d	+336	−123
	pH 7.5	−310 ± 5 d	+8 ± 3 d	−474 ± 5 e	+318	−142
NP2(D1A)	pH 5.5	−318 ± 2 f	+48 ± 2 f	−408 ± 2 f	+366	−90
	pH 7.5	−325 ± 4 f	−20 ± 2 f	−440 ± 3 f	+305	−115
GSHM–NP2	pH 7.5	−360 ± 5 f	−15 ± 3 f	−451 ± 3 f	+345	−91
NP3	pH 5.5	−321 ± 5 d	+73 ± 1 e	−339 ± 2 e	+394	−18
	pH 7.5	−335 ± 1 d	+13 ± 1 e	−403 ± 1 e	+348	−68
NP4	pH 5.5	−259 ± 2 d	+94 ± 5 d	−393 ± 2 d	+353	−134
	pH 7.5	−278 ± 4 d	–g	−404 ± 1 d	–	−126
wt NP7 h	pH 5.5	−253 ± 5	+94 ± 5	−254 ± 5	+346	−1
	pH 7.5	−268 ± 4	+109 ± 7	−319 ± 8	+377	−51
NP7(Δ1-3) h	pH 5.5	−109 ± 6	+157 ± 3	−225 ± 6	+266	−116
	pH 7.5	−182 ± 5	+228 ± 4	−254 ± 6	+410	−72
$E_{\mathrm{NP}7(\Delta 1-3)}^{\mathrm{o}}-E_{\mathrm{NP}7}^{\mathrm{o}}$	pH 5.5	+144	+63	+29
	pH 7.5	+86	+119	+65

^aExcept when noted all were measured in 100 mM NaH₂PO₄/NaOH (pH 5.5 or 7.5).

^bNo ligand added.

^cFrom (16).

^dFrom (28).

^eFrom (21).

^fFrom (44).

^gThis value could not be measured because of facile dissociation of NO (28).

^hThis work; determined in 100 mM MOPS/NaOH (pH 7.5) or 100 mM NaH₂PO₄/NaOH (pH 5.5), respectively.