Hemoglobin, function properties

Pyridoxal Derivatives. Various aldehydes of pyridoxal (Table 3) react with hemoglobin at sites that can be somewhat controlled by the state of oxygenation (36,59). It is thereby possible to achieve derivatives having a wide range of functional properties. The reaction, shown for PLP in Figure 3, involves first the formation of a Schiff s base between the amino groups of hemoglobin and the aldehyde(s) of the pyridoxal compound, followed by reduction of the Schiff s base with sodium borohydride, to yield a covalendy-linked pyridoxyl derivative in the form of a secondary amine. 

Detection of Variants With Altered Functional Properties. When substitutions In either a-or 3-chains Involve amino acid residues that participate In the contact with heme or the contact between chains, changes In functional properties can occur and the determination of the oxygen affinity of the blood sample or of an Isolated hemoglobin variant Is desirable. Oxygen affinity Is affected by temperature, pH, salt concentration, the level of 2,3-dlphosphoglycerate (2,3-DPG), and to a lesser extent by the concentration of the hemoglobin. The concentration of 2,3-DPG In blood changes rather rapidly after collection and a... 

The a-helix is the most abundant secondary structural element, determining the functional properties of proteins as diverse as a-keratin, hemoglobin and the transcription factor GCN4. The average length of an a-helix in proteins is approximately 17 A, corresponding to 11 amino acid residues or three a-helical turns. In short peptides, the conformational transition from random coil to a-helix is usually entropically disfavored. Nevertheless, several methods are known to induce and stabilize a-helical conformations in short peptides, including ... 

E. Antonini, J. Wyman, M. Brunori, C. Fronticelli, E. Bicci, and A. Rossi-Fanelli, Studies of the relations between molecular and functional properties of hemoglobin, J. Biol. Chem. 240, 1090-1103 (1965). 

The structural and functional properties of human hemoglobin (Hb) have been the subject of study for decades, stimulated by the intriguing characteristic of positive cooperativity. How do the four subunits that compose the Hb tetramer communicate with one another The answer to this question has been sought primarily through the comparison of deoxy with oxy Hb. However, to understand the molecular mechanism of a chemical reaction, it is necessary to characterize the intermediate(s) of the process, and the reaction of Hb with O2 is no exception. 

Amiconi G., Zolla L., Vecchini P., Brunori M., Antonini E. The effect of macromolecular polyanions on the functional properties of human hemoglobin. Eur. J. Biochem. 1977 76 339-343. 

Bonaventura, J., Bonaventura, C., Giardina, B., Antonini, E., Brunori, M., Wyman, J. 1972. Partial restoration of normal functional properties in carboxypeptidase A-digested hemoglobin. Proc. Nat. Acad. Sci. U. S. A. 69, 2174-2178. 

Giardina, B., Corda, M., Pellegrini, M.G. Condo, S.G. Brunori, M. (1985). Functional properties of the hemoglobin system of two diving birds (Podiceps nigricollis and Phalacrocorax carbosinensis). Mol. Physiol, 7, 281-92. 

Hiebl, 1., Weber, R.E., Schneeganss, D. Braunitzer, G. (1989). The primary structures and functional properties of the major and minor hemoglobin components of the adult white-headed vulture (Trigonoceps occiptalis, Aegypiinae). Biol. Chem. Hoppe-Seyler, 370, 699-706. 

In a recent study Chiancone et al. [469] investigate the Cl binding to the two main hemoglobin components in trout blood, Hb-Trout I and Hb-Trout IV. These two hemoglobins from the species Salmo irideus are electrophoretically different and may be separated. The two components have strikingly different functional properties. A Root effect (the equivalent of the Bohr effect for human hemoglobin),... 

The effects of solvent perturbation on the functional properties of hemoglobin have also been studied. The study was started by measuring the effects of methanol, ethanol, iso-propanol and n--propanol on the oxygen affinity of hemoglobin. ... 

Effects of deuteration on the conformational stability and on the functional properties of hemoglobin have been already reported (7) These effects have been attributed by the authors to asymmetric partial deuteration of the protein (7) such interpretation has been questioned by other authors (8). 

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