Collagen ascorbic acid vitamin

Ascorbic acid—vitamin C—is an essential nutrient that the human body cannot manufacture from other compounds. It is needed for the formation of collagen, the protein that makes up connective tissue, and is essential to muscles, bones, cartilage, and blood vessels. It is a strong antioxidant, preventing damage from oxygen free radicals. 

Ascorbic acid. The potato is a significant dietary source of ascorbic acid (vitamin C), which is necessary for normal collagen formation and which acts as an antioxidant. In... 

Ascorbic acid (vitamin C), the antiscurvy vitamin, is used by the body to form and maintain intercellular and skeletal material such as the collagen of fibrous tissue and the matrix of bone, dentin, and cartilage. Milk and milk products are not considered a significant source of this vitamin and should not be relied upon as such. Freshly drawn cow s milk contains about 2 mg ascorbic acid per 100 g milk, but as vitamin C is heat labile and easily destroyed by oxidation, the vitamin C content of pasteurized milk is reduced to about 0.94 mg/100 g. 

Ascorbic acid (vitamin C fig. 10.16) is the reducing agent required to maintain the activity of a number of enzymes, most notably proline hydroxylase, which forms 4-hydroxyproline residues in collagen. Hydroxyproline (see fig. 10.16c) is not synthesized biologically as a free amino acid but rather is created by modification of proline residues already incorporated into collagen. The hydroxylation reaction occurs as the protein is synthesized in the endoplasmic reticulum. At least a third of the numerous proline residues in collagen are modified in this way, substantially increasing the resistance of the protein to thermal denaturation. 

Ascorbic acid (vitamin C) is a water-soluble vitamin but is not part of the B group. It is a metabolic requirement for all species but is a dietary requirement only for those that lack the enzyme for its synthesis (primates, guinea pigs, certain birds, fish). Therefore, it is not required in poultry diets. It is involved in the formation and maintenance of intercellular tissues having collagen or related substances as basal constituents. 

One-third of the amino acid residues in collagen are Gly, while another quarter are Pro. The hydroxylated amino acids 4-hydroxyproline (Hyp) and 5-hydroxylysine (Hyl) are formed post-translationally by the action of proline hydroxylase and lysine hydroxylase. These Fe2+-containing enzymes require ascorbic acid (vitamin C) for activity. In the vitamin C deficiency disease scurvy, collagen does not form correctly due to the inability to hydroxylate Pro and Lys. Hyl residues are often post-translationally modified with carbohydrate. 

Ascorbic acid (vitamin C) is an alpha-hydroxy acid derivative. It has been shown to stimulate collagen production and reduce melanin production. Under identical conditions, classification of the acids described above in order of strength would give the top three as ... 

The answer is e. (Murray, pp 627-661. Sciiver, pp 3897-3964. Sack, pp 121-138. Wilson, pp 287-320.) Ascorbic acid (vitamin C) is found in fresh fruits and vegetables. Deficiency of ascorbic acid produces scurvy, the sailor s disease. Ascorbic acid is necessary for the hydroxylation of proline to hydroxyproline in collagen, a process required in the formation and maintenance of connective tissue. The failure of mesenchymal cells to form collagen causes the skeletal, dental, and connective tissue deterioration seen in scurvy. Thiamine, niacin, cobalamin, and pantothenic acid can all be obtained from fish or meat products. The nomenclature of vitamins began by classifying fat-soluble vitamins as A (followed by subsequent letters of the alphabet such as D, E, and K) and water-soluble vitamins as B. Components of the B vitamin fraction were then given subscripts, e.g., thiamine (Bi), riboflavin (B2), niacin [nicotinic acid (B3)], panthothenic acid (B5), pyridoxine (Bg), and cobalamin (B ). The water-soluble vitamins C, biotin, and folic acid do not follow the B nomenclature. 

An individual collagen polypeptide chain has a large number of repeating amino acid sequences, most often glycine-X-Y, where X is often proline and Y is often hydroxyproline. Lysine, in its pure form or modified to hydroxylysine, is also found in collagen. Both hydroxyproline and hydrox-ylysine are formed via the enzyme-catalyzed oxidations of the profine and lysine amino acid side chains, which occur after the collagen polypeptide has been synthesized. These enzymatic reactions reqtiire ascorbic acid (vitamin C) as a cofactor. 

Proline is incorporated into polypeptide precursors of collagen. In the procollagen polypeptide (precursor to the mature collagen), proline is converted to hydroxyproline by the enzyme procollagen proline hydroxylase (Figure 21.4). As seen in the figure, the reaction requires ascorbic acid (vitamin... 

Ascorbic acid (vitamin C) Only required by some avian species Hydroxylation of proline residues in collagen... 

Ascorbic acid (vitamin C), found in citrus fruits and vegetables, is important in metabolic reactions in the body, in the synthesis of collagen, and in the prevention of scurvy. If the mass percent composition of ascorbic acid is 40.9% C, 4.58% H, and 54.5% O, what is the empirical formula of ascorbic acid ... 

Vitamin C, ascorbic acid, is a coenzyme for the enzyme prolyl hydroxylase. The action of this enzyme is critical for the formation of normal collagen, a key component of structural and connective tissues. 

Ascorbic acid or vitamin C is found in fruits, especially citrus fruits, and in fresh vegetables. Man is one of the few mammals unable to manufacture vitamin C in the liver. It is essential for the formation of collagen as it is a cofactor for the conversion of proline and lysine residues to hydroxyproline and hydroxylysine. It is also a cofactor for carnitine synthesis, for the conversion of folic acid to folinic acid and for the hydroxylation of dopamine to form norepinephrine. Being a lactone with two hydroxyl groups which can be oxidized to two keto groups forming dehydroascorbic acid, ascorbic acid is also an anti-oxidant. By reducing ferric iron to the ferrous state in the stomach, ascorbic acid promotes iron absorption. 

Deficiency may occur in infants if no fruits or vegetables are added to their milk formulas. In alcoholics, and in elderly subjects who consume inadequate diets vitamin C deficiencies are frequent. Severe ascorbic acid deficiency is characterized by the syndrome known as scurvy. Its manifestations are generally based on a loss of collagen. Symptoms include hemorrhages, loosening of teeth. In children cellular changes in the long bones occur. 

Vitamin C (ascorbic acid) is essential for the maintenance of the ground substance that binds cells together and for the formation and maintenance of collagen. The exact biochemical role it plays in these functions is not known, but it may be related to its ability to act as an oxidation-reduction system. 

As noted, vitamin C is needed for the production of collagen in the body, but it is also essential in the production of certain hormones such as dopamine and adrenaline. Ascorbic acid is also essential in the metabolism of some amino acids. It helps protect cells from free radical damage, helps iron absorption, and is essential for many metabolic processes. The dietary need of vitamin C is not clearly established, but the U.S. National Academy of Science has established a recommended dietary allowance (RDA) of 60 mg per day. Some groups and individuals, notably Linus Pauling in the 1980s, recommend dosages as high as... 

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