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Question on amino acids?Amino acids such as valine, leucine, isoleucine and phenyl...

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lizg10 | Student, Undergraduate | eNotes Newbie

Posted January 12, 2010 at 8:53 PM via web

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Question on amino acids?

Amino acids such as valine, leucine, isoleucine and phenyl alanine are often found in the interior of water soluble proteins, while arginine, lysine and aspartic acid are often found on the surface. Explain this observation. Where would you expect to find alanine and glutamic acid in this protein. Relate your answer to the structure of the amino acids.

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giorgiana1976 | College Teacher | Valedictorian

Posted January 13, 2010 at 2:46 AM (Answer #1)

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Alanine can exist in 3 forms: two enantiomers and an optically inactive substance. The combined state is found in various proteins such as casein, gelatin, especially silk proteine.Beta Alanine is found in nature as a component of pantothenic acid, which is a Vitamin from B complex, representing one of the growth factors. This is the only beta-amino acid existent in nature.

Asparagic acid and glutamic acid were obtained first by hydrolysis of mono-amides. Glutamic acid can be obtained by synthesis, too. Both acids have important role in protein metabolism. Asparagic acid has a similar position in the formation of amino acids in plants.

Albumins are the most common proteins. They are particularly prevalent in the animal kingdom, are found in blood serum (serum albumin), in egg whites (egg albumin), milk, etc.. Albumins are  met  in vegetable proteins, although to a lesser extent, for example, wheat seeds (leucosina) or ricin (castor).Proteins are easily soluble in water and diluted   solutions of electrolytes, by heating ,coagulates the solution, they contain more glutamic acid, in solution have most neutral reaction.

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raid1802 | Honors

Posted June 2, 2010 at 5:19 PM (Answer #2)

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Arginine is an amino acid, also referred to as L-arginine. It is a popular medication for sexual dysfunctions and used to increase libido in both men and women. Arginine is needed by the body to make nitric oxide, a compound that works to relax blood vessels and allow more blood to flow through the sexual organs to improve clitoral sensation.

Arginine can be found in dairy products such as cottage cheese, ricotta, milk, yogurt and whey protein drinks. It can also be found in beef, pork, poultry and other seafoods (e.g. halibut, lobster, salmon, shrimp, snails, tuna).

Some plant sources of arginine are wheat germ and flour, buckwheat, chickpeas, cooked soybeans and seeds (pumpkin, sesame, sunflower).

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