Muscle proteins changes

Calcium is the trigger behind the muscle contraction process (24,25). Neural stimulation activates the release of stored Ca(Il) resulting in a dramatic increase in free calcium ion levels. The subsequent binding of Ca(Il) resulting in a dramatic increase in free calcium ion levels. The subsequent binding of Ca(Il) to the muscle protein troponin C provides the impetus for a conformational change in the troponin complex and sets off successive events resulting in muscle contraction. 

Meat products have to be stabilised in some cases, as meat lipids contain no natural antioxidants or only traces of tocopherols. Most muscle foods contain, however, an efficient multi-component antioxidant defence system based on enzymes, but the balance changes adversely on storage. The denaturation of muscle proteins is the main cause of the inbalance as iron may be released from its complexes, catalysing the lipid oxidation. Salting contributes to the negative effects of storage, as it enhances oxidation. Using encapsulated salt eliminates the deleterious effect of sodium chloride. 

When your muscles contract it is largely because many C-C sigma (single) bonds are undergoing rotation (conformational changes) in a muscle protein called... 

Soy proteins are used extensively in meat and meat products by the military, the school lunch program and consumers to save money. Their ultimate acceptability is equally dependent upon the nutritional, chemical, sensory and shelf life changes which occur when they are added. Soy proteins in meat products such as ground beef inhibit rancidity, improve tenderness, increase moisture retention, decrease cooking shrink, fat dispersion during cooking and have no important effect on microbiological condition. Concomittantly, inordinate amounts of added soy protein may cause the meat product to be too soft, exhibit an undesirable flavor and may lead to a decreased PER and a deficiency in B-vitamins and trace minerals. In emulsified meat products, soy protein effectively binds water but does not emulsify fat as well as salt soluble muscle protein. Prudent incorporation of plant proteins can result in an improvement of the quality of the meat product with inconsequential adverse effects. 

Loss of muscle protein in trauma is caused by increased degradation rather than decreased synthesis. The degradation is controlled by changes in the levels of glucocorticoids, insulin and the proinflammatory cytokines TNFa and IL-1. The proteolytic enzyme complex that degrades the protein is the proteasome (Chapter 8). The mechanism by which the enzyme is activated is not known, but increased activities of the enzymes involved in ubiquitina-tion of proteins and an increase concentration of ubiquitin may play a role (Chapter 8). 

The formation of free radicals after lipid oxidation is known to play a key role in the deterioration of meat flavor 8, 23), Since proteins constitute a major portion of the muscle s composition, the relationship between chemically active radical species and decomposition of food flavor proteins and peptides needs to be studied in detail. Data has been presented showing the correlation of proteins with flavor (Figures 5 and 6). Data is now presented showing how soluble meat proteins change in an environment where free radicals are induced by a free-radical oxidation generating system or FROG (Figure 10). 

Bal, N.E., Geraskin, P.P. and Mishin, E.A. (1989). The composition of water soluble muscle proteins in Russian sturgeon and changes during tissue destruction of varying degree (In Russian). In Sturgeon Culture in Water Bodies of the USSR (V.I. Lukyanenko, ed.) Vol.l, pp. 16-18, Astrakhan. 

Hamm, R., and EE. Deatherage. 1960a. Changes in hydration and charges of muscle proteins during heating of meat. Food Res. 25 573-586. 

Most of the studies indicate that denaturation of muscle proteins plays the dominant role in the quality changes of the frozen stored meats. The muscle proteins of fish and other aquatic animals have been found to be much less stable than those of beef animals, pigs and poultry (1 ). The present paper will be limited primarily to fish muscle as one representative of vertebrate muscle and it will also deal primarily with the behavior of fish proteins at sub-zero temperatures. In order to do a thorough analysis within the space limit permitted, focus will be on the changes of the proteins per se leaving peripheral problems to other reviews (2-18). 

Actomyosin. Frequently, the change in amount of soluble actomyo-sin is regarded as the primary criterion of freeze denaturation. It must be remembered that solubility data do not tell precisely how much protein is denatured and how much is native rather, it provides a relative measure of denaturation. Solubility decreases have been found in frozen storage experiments with either intact muscle, protein solutions or with suspensions of isolated actomyosin. 

The water-activity relations, effects of displacements of water or effects of changes in the state of water must be the most important factors to trigger and to promote the denaturation of muscle proteins during frozen storage. 

Laurent, G.J., Sparrow, M.P. 4 Mlllward, D.J. (1978) Muscle protein turnover in the adult fowl II. Changes in rates of protein synthesis and breakdown during hypertrophy of the anterior and posterior latissimus dorsi muscle. Biochem. J. 176, 407-417. 

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