Trapping Hemoglobin in Rigid Matrices: Fine Tuning of Oxygen Binding Properties by Modulation of Encapsulation Protocols

Figures & data

Figure 1 Representative absorption spectrum of hemoglobin encapsulated in silica gel (solid line). The contributions of deoxy- (dashed line), oxy- (dash-dot line) and met-hemoglobin (dash-dot-dot line) spectra resulting from the linear fitting are reported. The calculated fractional saturation is 0.45 and the fractional met-hemoglobin content is 0.1.

Figure 2 Hill plots of hemoglobin encapsulated in the absence of allosteric effectors (condition 1 in Table 1) (open inverted triangles), in the presence of strong allosteric effectors (condition 5 in Table 1) (open triangles), in the presence of a saturating concentration of chloride ions (condition 4 in Table 1) (closed squares). For comparison, the Hill plot of hemoglobin in solution in the absence of allosteric effectors (condition 7 in Table 1) (closed circles) is also reported. Solid lines through data points are the fit to the Hill equation.

Figure 3 p50 values (white bars) and Hill coefficients (black bars) of hemoglobin encapsulated in silica gels prepared according to conditions 1–6 in Table 1.

Table 1. Protocols, p50s and Hill coefficients of hemoglobin encapsulated in silica gel and in solution

	Sample	Protocol	p50 (torr)	n
1	Deoxyhemoglobin, no effectors	2 (30′)	12.4±0.2	0.94±0.02
2	Deoxyhemoglobin, no effectors	2 (90′)	26±1	0.95±0.03
3	Deoxyhemoglobin, 100 mM phosphate	1	33.6±0.5	0.80±0.01
4	Deoxyhemoglobin, 200 mM Cl^−	2	71.1 + 3.8	0.84±0.04
5	Deoxyhemoglobin, 10 mM IHP, 2 mM Bzf, 200 mM Cl^−	1	139±4	0.93±0.03
6	Deoxyhemoglobin, 10 mM IHP, 2 mM Bzf, 200 mM Cl^−	2	134±5	0.93±0.03
7	Solution, no effectors	–	2.61±0.05	2.36±0.06
8	Estimated p50 (from K1) in solution, no effectors	–	14.1±5	1.0±0.3
9	Estimated p50 (from K1) in solution, 10 mM IHP, 2 mM Bzf, 200 mM Cl^−	–	124±4	1.07±0.07