amino acids


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amino acids

The basic constituent of protein. Amino acids can be considered to be the ‘alphabet’ of letters from which proteins are written. Their properties are determined by their side chains. Body protein breaks down into 20 different amino acids. Some of these can be synthesized by the body but some can not. The latter are known as ‘essential amino acids’ and must be obtained from protein in the diet. Amino acids group together to form peptides. Linkages between amino acids are called peptide bonds. Dipeptides have two amino acids, polypeptides have many. Polypeptides join to form proteins. The reverse process occurs when proteins are digested. Some amino acids, such as glycine, arginine, aspartic acid and glutamic acid, also perform specific biological functions in addition to helping to form proteins. The German organic chemist Emil Fischer (1825–1919) elicited an understanding of amino acids, peptides and proteins which was of fundamental importance in the development of organic chemistry and biochemistry. He was awarded the Nobel Prize in Chemistry in 1902. See also STEREOISOMERS.

Amino acids

Proteins are made up of organic compounds called amino acids. The human body uses amino acids to build and repair body tissue. The body can make some of its own amino acids from other nutrients in the diet; these are called non-essential amino acids. Essential amino acids are those that cannot be made by the body but must be consumed in the diet. Animal proteins (like meat, eggs, fish, and milk) provide all of the amino acids.

amino acids

organic acids in which one or more of the hydrogen atoms is replaced by the amino group, NH2. They are the end-products of digestion of dietary protein and from them the body synthesizes its own proteins. Within the body amino acids also act as precursors of many other molecules essential for life. Amino acids may be categorized as essential or non-essential. essential amino acids: those that must be provided in the diet since the human body does not have the enzymes for their synthesis; of the 20 amino acids that are present in proteins or as free amino acids in the body, nine are 'essential' (histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine). Of these, three are known as branched-chain aminoacids (BCAA): leucine is oxidized to a significant extent during exercise, and tracer studies that follow leucine kinetics are often used as an estimation of protein turnover; isoleucine and valine can also serve as fuel sources. It has been claimed that ingestion of BCAA before and during exercise may improve the physiological and psychological responses, and that BCAA with arginine and/or other amino acids may promote growth hormone release, but other studies do not support this. There are no known toxic effects. See also ergogenic aids, gluconeogenesis; Table 1.
Table 1: Ergogenic aids: supplements used by athletes
SubstanceDescriptionClaimed ergogenic effectSupporting evidence
With clear scientific evidence
CaffeineStimulant in coffee and tea
  • Benefits performance by improving alertness, concentration, reaction time.
  • Increases fat oxidation during endurance exercise.
Improves performance in most events, except very short high-intensity exercise; increases cognitive functioning during exercise.
CreatineCarrier of high-energy phosphates in muscleIncreases the energy reserve, improves strength, reduces fatigue, and increases protein synthesisIncreases intramuscular Cr and PCr; improves performance in repeated sprint bouts (and reported to do so after even a single bout); improves recovery between bouts (but response varies between individuals). Anabolic properties unclear.
  • Sodium bicarbonate
  • Sodium citrate
BuffersImproves high-intensity exercise performance by limiting decrease in pH in ECF as a whole and indirectly in muscle ICFLarge doses can improve performance
With mixed scientific evidence
Antioxidant nutrientsVitamins, especially C and EProvides protection against muscle damage by reducing oxidative stressBenefits established at cellular level; no detectable aid to performance
ArginineAmino acid in normal dietStimulates release of growth hormone, promoting gain in muscle mass and strengthSome evidence of GH promotion when combined with other amino acids (ornithine, lysine, BCAA); no conclusive evidence of effect when taken alone
Branched-chain amino acids (BCAA)Leucine, isoleucine and valine
  • Retards the development of central fatigue and so improves performance.
  • Improves efficiency of training
No good evidence of improved endurance performance. Evidence of accelerated recovery from muscle fatigue when given with other amino acids during eccentric exercise training
GlutamineAmide of amino acid glutamateMaintains a healthy immune system during training and improves muscle glycogen resynthesisDoes not affect immune function; possibly affects muscle glycogen resynthesis
GlycerolComponent of triacylglycerol moleculeInduces hyperhydration, decreases heat stress, and improves performanceDoes have the first two actions, but effects on performance are unclear
Lacking scientific support
AndrostenedioneSynthetic productIncreases testosterone and thus muscle mass and strength, and improves recoveryDoes not increase testosterone secretion; has no effect on strength
Hydroxy-methyl butyrate (HMB)Metabolite of the amino acid leucineEnhances gain in body mass and strength associated with resistance training, and improves recoveryPossible small effects only on lean body mass and strength
BoronMicronutrient present in vegetables and non-citrus fruitsIncreases testosterone levels, to improve bone density, muscle mass, and strengthImproves bone mineral density in postmenopausal women; no effect on bone density, muscle mass or strength in men
CarnitineSubstance important for fatty acid transport into mitochondriaImproves fat oxidation, helps weight lossNo supporting evidence
CholinePrecursor of acetylcholineImproves performance, decreases fatigue and enhances fat metabolismNo supporting evidence
Chromium (chromium picolinate)Micronutrient that potentiates insulin actionPromotes fat oxidation and muscle buildingNo supporting evidence
Coenzyme Q10Part of the electron transport chain in the mitochondriaImproves aerobic capacity and cardiovascular dynamicsNo supporting evidence
GinsengRoot of the Araliaceous plantImproves strength, performance, stamina, and cognitive functioning; reduces fatigueNo supporting evidence
InosineNucleoside found naturally in brewer's yeast and organ meatsIncreases ATP stores, improve strength, training quality, and performanceNo supporting evidence
Medium-chain triacylglycerols (MCT)Triglycerides containing fatty acids with a carbon chain length of 6-10Improves energy supply, reduces rate of muscle glycogen breakdown, and improves performanceNo supporting evidence
PyruvateEnd-product of aerobic glycolysisImproves endurance capacity and recovery; increases glycogen storageLimited supporting evidence
PolylactatePolymer of lactateProvides energyNo effects on performance
Wheat germ oilWheat embryo extractImproves enduranceNo supporting evidence

amino acids

'building blocks' of globular and structural body proteins; essential amino acids cannot be synthesized within the body and must be supplied within the diet; non-essential amino acids can be synthesized by the body

Patient discussion about amino acids

Q. what are Amino Acids and what are their for? how do i need to do to keep it "going "?

A. Amino acids are the basic structural building units of proteins. They form short polymer chains called peptides or longer chains called either polypeptides or proteins. The process of such formation from an mRNA template is known as translation, which is part of protein biosynthesis. Twenty amino acids are encoded by the standard genetic code and are called proteinogenic or standard amino acids. Other amino acids contained in proteins are usually formed by post-translational modification, which is modification after translation in protein synthesis. These modifications are often essential for the function or regulation of a protein; for example, the carboxylation of glutamate allows for better binding of calcium cations, and the hydroxylation of proline is critical for maintaining connective tissues and responding to oxygen starvation. For full article: http://en.wikipedia.org/wiki/Amino_acid Hope this helps.

More discussions about amino acids
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