Essay on Amino Acid Metabolism: normal and abnormal

Protein is one of the basic fundamental groups of essential nutrition. As protein is broken down in the body it forms amino acids. There are about 28 commonly known amino acids that are combined in various ways to create proteins. In addition to the amino acids that combine to form the body’s proteins, other amino acids are important in metabolic functions. For example, taurine, citrulline and glutathione may act as neurotransmitters or precursors of neurotransmitters.

Amino acids also enable vitamins and minerals to perform their functions. For example, even if the body contains enough iron it may not be utilized properly if there is a tyrosine deficiency. If there are not enough amino acids present, a variety of symptoms may be expressed and often amino acid deficiencies produce similar symptoms. For example, the depressed elderly patient may be deficient in tyrosine, tryptophan, phenylalanine or valine.

An excess of amino acids and byproducts can also result in pathology. For example, some people are born with an inability to metabolize the branched-chain amino acids, like the potentially fatal branched-chain ketoaciduria, that can result in neurological damage.1 In fact there are many defects in amino acid metabolism that include phenylketonuria, Tyrosinemia, Alcaptonuria, Homocystinuria, Histidinemia, Maple Syrup Urine Disease, Methylmalonic Aciduria, non-ketonic hyperglycinemia and hyperlysinemia. I have focused on five of these errors of metabolism in this review.

Alanine plays a role in the transfer of nitrogen from muscle to the liver. It assists in the break down of glucose and also the excretion of toxic substances from the muscle tissue post-exercise.1 The liver accumulates alanine and reverses the transamination that occurs in the muscle with the subsequent release of urea. The glucose-alanine cycle is the transfer of alanine from muscle to liver, and then glucose transport back from the liver to the muscle. …

Tags: amino acids, B12, body, deficiency, enzyme deficiency, metabolism, nutrition, protein

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