INFLUENCE OF THE POLYMERIZATION STEP ALONE ON OXYGEN-AFFINITY AND COOPERATIVITY DURING PRODUCTION OF HYPERPOLYMERS FROM NATIVE HEMOGLOBINS WITH CROSS-LINKERS
Wkr. Barnikol, INFLUENCE OF THE POLYMERIZATION STEP ALONE ON OXYGEN-AFFINITY AND COOPERATIVITY DURING PRODUCTION OF HYPERPOLYMERS FROM NATIVE HEMOGLOBINS WITH CROSS-LINKERS, Artificial cells, blood substitutes, and immobilization biotechnology, 22(3), 1994, pp. 725-731
The aim of this study was to find out how the polymerization per se ch
anges oxygen affinity (P5O) and cooperativity (n50) of various soluble
huge hyperpolymers prepared from native hemoglobins by crosslinking.
Increase of cooperativity would be expected considering natural hemogl
obin networks. Those hyperpolymers with molecular weights of some 10(6
) g/mol are candidates for artificial oxygen-carrying blood additives
rather than volume substitutes. Human and bovine hemoglobin reacted wi
th several crosslinkers (2,5-diisothiocyanatobenzenesulfonate (DIBS);
4,4'-diisothiocyanatostilbene-2,2'-disulfonate (DIDS); 1,3-butadiene d
iepoxide (BUDE); glutaraldehyde (GDA)) in concentrated (case 1) and di
luted (case 2) hemoglobin solutions. With high concentration hyperpoly
mer and with low concentration only monomer products were obtained. P5
0 and n50 of the products were determined at pH = 7.4, PCO2 = 40 mmHg,
temp. = 37 degrees C. The difference of properties in both cases are
regarded as the influence of polymerization per se. Considering this d
ifference we found with almost all combinations of hemoglobin and cros
slinker an increase of O-2 affinity, with DIBS and DIDS cooperativity
was not changed and with BUDE and GDA it was decreased. As compared wi
th native hemoglobin loss of cooperativity is considerable in any comb
ination and condition, but comparing human and bovine hemoglobin the f
irst seems to maintain better cooperativity. In contrast bovine hemogl
obin as compared with human hemoglobin maintains better or even decrea
ses its O-2 affinity upon reaction with the crosslinkers forming both,
monomer and hyperpolymer products, especially in the deoxy state. DIB
S and DIDS react very similarly. As a general conclusion only deoxy st
ate reactions led to appropriate products regarding an artificial oxyg
en carrier. A differentiated analysis of some samples clearly indicate
s crosslinking with increased homotropic cooperativity on going from m
onomer to hyperpolymer reaction products.