Hemoglobin properties

Mieyal JJ, Acherman RS, Blumer JL, Freeman LS (1976) Characterization of enzyme-like activity of human hemoglobin. Properties of the hemoglobin-P-450 reductase-coupled aniline hydroxylase system. J Biol Chem 251 3436-3441... 

The sacroplasmic proteins myoglobin and hemoglobin are responsible for much of the color in meat. Species vary tremendously in the amount of sacroplasmic proteins within skeletal muscle with catde, sheep, pigs, and poultry Hsted in declining order of sarcoplasmic protein content. Fat is also an important component of meat products. The amount of fat in a portion of meat varies depending on the species, anatomy, and state of nutrition of the animal. The properties of processed meat products are greatiy dependent on the properties of the fat included. Certain species, such as sheep, have a relatively higher proportion of saturated fat, whereas other species, such as poultry, have a relatively lower proportion of saturated fat. It is well known that the characteristic davors of meat from different species are in part determined by their fat composition. 

After these reports there were many attempts to administer hemoglobin solutions to humans. Many of these patients did well, but others demonstrated hypertension, bradycardia, oliguria, and even anaphylaxis. These untoward effects were not correlated with specific biochemical properties of the solutions themselves. 

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. 

An interesting property of DBBF—hemoglobin is its thermal stability. This property has been used to achieve both a partial purification of the cmde reaction mixture after cross-linking and inactivation of vimses in the final product (101,102). 

Table 5. Properties of Pyridoxylated Polymerized Hemoglobin (PLP-polyHb) ...

R. Benesch and R. E. Benesch, iu E. Antonini, L. R. Rossi-Bemardi, and E. Chiancone, eds.. Methods in En mology Hemoglobins, Academic Press, New York, 1981, pp. 147—158. Preparation and properties of hemoglobin modified with dedvatives of Pyridoxal. 

In addition to enzymes, noncatalytic proteins may exhibit many of these properties hemoglobin is the classic example. The allosteric properties of hemoglobin are the subject of a Special Focus beginning on page 480. 

Much research focuses on the structures, properties, and uses of the complexes formed between d-metal ions acting as Lewis acids and a variety of Lewis bases, partly because they participate in many biological reactions. Hemoglobin and vitamin B12, for example, are both complexes—the former of iron and the latter of cobalt (Box 16.1). Complexes of the d-metals are often brightly colored and magnetic and are used in chemistry for analysis, to dissolve ions (Section 11.13), in the... 

Photo 8 Linus Pauling with Charles D. Coryell (left), who collaborated in the study of the magnetic properties of hemoglobin (SP 83, SP 84). Picture taken about 1933. 

Chapter 11. Hemoglobin Oxygen Bonding and Magnetic Properties 849... 

THE ALLOSTERIC PROPERTIES OF HEMOGLOBINS RESULT FROM THEIR QUATERNARY STRUCTURES... 

The properties of individual hemoglobins are consequences of their quaternary as well as of their secondary and tertiary structures. The quaternary structure of hemoglobin confers striking additional properties, absent from monomeric myoglobin, which adapts it to its unique biologic roles. The allosteric (Gk alios other, steros space ) properties of hemoglobin provide, in addition, a model for understanding other allosteric proteins (see Chapter 11). 

Hemoglobins bind four molecules of Oj per tetramer, one per heme. A molecule of Oj binds to a hemoglobin tetramer more readily if other Oj molecules are already bound (Figure 6-4). Termed cooperative binding, this phenomenon permits hemoglobin to maximize both the quantity of O2 loaded at the PO2 of the lungs and the quantity of O2 released at the PO2 of the peripheral tissues. Gooperative interactions, an exclusive property of multimeric proteins, are critically important to aerobic life. 

Figure 38-4. Examples of three types of missense mutations resulting in abnormal hemoglobin chains. The amino acid alterations and possible alterations in the respective codons are indicated. The hemoglobin Hikari p-chain mutation has apparently normal physiologic properties but is electrophoretically altered. Hemoglobin S has a p-chain mutation and partial function hemoglobin S binds oxygen but precipitates when deoxygenated. Hemoglobin M Boston, an a-chain mutation, permits the oxidation of the heme ferrous iron to the ferric state and so will not bind oxygen at all.

Fetal hemoglobin Is the major hemoglobin of the red cells of the fetus and the newborn. It has the characteristic property of being resistant to denaturatlon by alkali Hb-F Is composed of two a-chalns (the same as In Hbs A and A2) and two... 

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