Polymorphism of Pramenka sheep hemoglobin in Central Bosnia

The study of the hemoglobin polymorphism was performed on blood samples, taken from areas inhabited by Pramenka sheep in Central Bosnia: the area of the mountain Vlasic, the upper flow of the river Vrbas and Kupres plateau. Dupska pramenka sheep inhabits the mountain Vlasic and the areas of surrounding municipalities. Privorska pramenka sheep inhabits the area around the upper flow of the river Vrbas and the mountain Vranica and Kupreska pramenka sheep inhabits Kupres plateau. HbA gene frequency was 0.31 and HbB gene frequency was 0.69 for Dupska pramenka sheep. Privorska pramenka sheep had a frequency of 0.33 for the HbA gene, and 0.67 for the HbB gene, in its population. Kupreska pramenka sheep had the lowest frequency of the HbA gene, (0.30), and therefore the maximum frequency of the HbB gene. Hemoglobin genotype frequencies for all investigated types of Pramenka sheep breed are in equilibrium. Investigated types of Pramenka sheep breed inhabit areas adjacent to each other. They are phenotypically quite similar and have a similar frequency of genotype polymorphism of hemoglobin. The difference between them is not statistically significant.

Simultaneous Determination of Hemoglobin and Myoglobin Oxygen Binding Curves by Spectral Curve Fitting

A completely optical method is described for the simultaneous determination of hemoglobin and myoglobin oxygen saturation. Solution oxygen concentrations were computed from measurements of phosphorescence decay of a soluble palladium porphyrin using the Stern-Volmer quenching relationship. Visible absorption spectra were recorded of hemoglobin/myoglobin mixtures progressively deoxygenated by bacterial aerobic metabolism. Separate hemoglobin and myoglobin oxygenation curves were resolved from the spectra of solutions containing both proteins by curve fitting, with the use of singular value decomposition of the spectra vs. oxygen concentration matrix. The method yielded a P50 of 1.2 Torr for horse heart myoglobin at 24 ± 1°C, while the P50 for sheep hemoglobin was 23 Torr at the same temperature. These values, obtained from mixtures, compare favorably with literature values determined for hemoglobin and myoglobin separately.

Oxygen-linked CO2 transport in sheep blood

We have analyzed oxygen-linked carbamate formation in sheep hemoglobin B by measuring a) the effect of CO2 on oxygen affinity and Bohr effect in red cell suspensions and dilute (1.3 mM Hb4) and concentrated (5 mM Hb4) hemoglobin solutions at 37 degrees C and b) CO2 binding curves of deoxygenated and oxygenated whole blood and hemoglobin solutions, respectively, at the same temperature. In the presence of CO2 both the Bohr effect and oxygen affinity were significantly lower in 1.3-mM Hb4 solutions than in either red cell suspensions or 5-mM Hb4 solutions, while in the absence of CO2 Bohr effect and oxygen affinity did not differ significantly in those preparations. Likewise, the fraction of oxygen-linked carbamate obtained from CO2 binding curves was found to be higher in 1.3-mM Hb4 (0.156 M HbCO2/M HbO2) solutions than in 5-mM Hb4 solutions (0.12 M HbCO2/M HbO2) at pH 7.2. We conclude that hemoglobin concentration affects formation of oxygen-linked carbamate. Total oxygen-linked CO2 in sheep whole blood amounted to 0.18 M CO2/M O2 of which 70% is oxygen-linked carbamate. Assuming a respiratory quotient of 0.85, the contribution of oxygen-linked CO2 to carbon dioxide exchange in sheep blood was computed to be 21%.

Interpretation of Nonhyperbolic Behavior in Enzymic Systems. I. Differentiation of Model Mechanisms

Mechanistic interpretation of nonhyperbolic rate and binding responses of enzymic reactions involves interlaced distinctions between steady-state and quasi-equilibrium kinetics, between the effects of K, V, and KV types of subunit interactions, and between the effects of different model mechanisms. Therefore (a) the steady-state and quasi-equilibrium predictions of selected kinetic models were analyzed. In most instances the degree of the rate function is a good discriminator between the two types of kinetics. (b) Sensitive detection of K effects in quasi-equilibrium is possible by observing the dependence of the ratio (relative velocity/fractional binding) on the substrate concentration, (c) Relationships between Adair binding constants and constants of models proposed by Pauling, by Monod et al., and by Koshland et al. permit testing the validity of these models to experimental binding data. For illustration the results of Roughton on the binding of oxygen to sheep hemoglobin have been analyzed, which appear to exclude the applicability of models of Pauling and Koshland, but may admit the mechanism of Monod et al. These criteria have been discussed in terms of a general scheme of presently feasible model differentiations.