Amino acids dispensable

Essential and non-essential (indispensable and dispensable) amino acids... 

An interesting possibihty, never investigated, is that the bear possesses the ability to synthesise both dispensable and non-dispensable amino acids de novo, from the ammonia released by the microorganisms. As far as is known, no mammal possesses the enzymes necessary to synthesise the indispensable amino acids. It would be interesting if another adaptation to such a long hibernation is development of enzymes necessary to synthesise indispensable amino acids. This possibility is supported by the... 

Milk is a remarkably complex biological fliud. It contains several hundred different molecules including enzymes and also different cells, e.g. inunune cells. In particular, it contains proteins, fat, lactose, both the indispensable and dispensable amino acids, essential fatty acids, micronutrients, cholesterol and phospholipids. Milk is essential for the first four months of life. The major protein in milk is... 

In Table 1.5 the classical amino acids are segregated according to their necessity in the diet, Those that are required to maintain life are called indispensabJe (essenfioJ) amino acids. Those that may be present in the diet but can be omitted without threatening life are called dispensable (norte5sc dw0 amino acids. The proteins of the most value, from a nutritional point of view, are the ones that contain all the indispensable amino acids as well as a variety of dispensable amino acids. 

Biosynthesis of Dispensable Amino Acids Clucogt icand Ketogcnic Amino Adds... 

Protein comes from the Greek word meaning to take first place. Proteins, found in every living cell, are composed of amino acids. Of the twenty-two known amino acids, nine are essential in the diet. Nonessential (dispensable) amino acids are derived from the essential ones or manufactured in the body. Protein, which yields about 4 calories per gram, is inefficient as a source of ener. However, with insufficient carbohydrate, the hody converts protein into glucose for enei. Protein huilds and repairs hody tissue. Amino acids may function as precursors for transport substances such as hpoprotein. Complete proteins, found in meats, eggs, and milk, contain all essential amino acids. Plant sources such as legumes and nuts lack at least one essential amino acid and are incomplete proteins. 

Protein requirements depend on the nature of the proteins and their composition. Strictly speaking the need for protein is a need for the essential amino acids (page 277) which the body is unable to synthesize for itself. However, the so-called dispensable amino acids also fulfil an important nutritional role, since not only are they directly incorporated into proteins but they also provide a non-specific source of nitrogen for the synthesis of a great variety of compounds. 

The non-essential or dispensable amino acids, which can be synthesized from metabolic intermediates, as long as there is enough total protein in the diet. If one of these amino acids is omitted from the diet, nitrogen balance can still be maintained. 

ESSENTIAL AND NONESSENTIAL. In order for a protein to be synthesized in the body, all of its constituent amino acids must be available. Some of the amino acids can be synthesized within the body. These are called nonessential or dispensable amino acids. If the body cannot synthe-... 

Even in infants the essential amino acids make up only about 35% of the total need for protein. In adults, essential amino acids account for less than 20% of the total protein requirement Most proteins contain plenty of dispensable amino acids usually, the concern is to meet the essential amino acid needs, particularly of infants and children. 

SYNTHESIS. The basic structural components of protein are amino acids. Many of the amino acids can be synthesized within the body. These are called nonessential amino acids or dispensable amino acids. If the body cannot synthesize sufficient amounts of certain amino acids to carry out physiological functions, they must be provided in the diet hence, they are referred to as essential or Indispensable amino acids. Actually, it is not entirely correct to say that all indispensable amino acids need to be provided in the diet rather, the requirement is for the preformed carbon skeleton of the indispensable amino acids, except in the case of lysine and threonine. 

The amino acids are termed as a-amino acids if both the amino and carboxylic groups are attached to same carbon atom. The a-carbon atom is linked to side chain which is different for all the 20 amino acids found in proteins. Table 3 provides a list of all the 20 amino acids. Amino acids are also referred to as residues in molecular biophysics. Of the amino acids. Arginine, Valine, Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Tryptophan and Threonine are Essential Amino Acids as they can t be synthesised by the human body. However, Histidine and Arginine can be synthesised in the adult body even if not in growing children, and can therefore also be known as Semi-Essential Amino Acids. The rest all are Non-Essential or Dispensable Amino Acids as they can be formed by the body. Molecular structure of the amino acids is shown in Figs. 13, 14, 15, and 16. 

Stucki, W.P and A.E. Harper, 1961. Importance of dispensable amino acids for normal growth of chicks. J. Nutr. 74, 377-383. 

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