|Nutrition and Nutrients|
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Amino Acids The Alphabet of Life
Amino acids are the alphabet characters of body proteins. Proteins are chains of amino acids linked together like beads on a necklace. The individual amino acids fall into two groups: the essential AA's, which must be ingested, and the non-essential AA's, which can be synthesized in the body and need not appear in the food. A total of 9 amino acids are considered essential, while another 11 or so can be synthesized from the essential amino acids.
There are other amino acids that appear in nature that are not included in protein structure. These odd amino acids appear especially in plants, where they may have roles as insect deterrents. An occasional non-nutrient amino acid may be useful in the food supply, as an accessory nutrient -taurine is a prime candidate.
Essential amino acids : Histidine, isoleucine, Leucine, lysine, methionine phenylalanine, threonine tryptophan, and valine. Nonessential amino acids: Alanine, arginine, aspartic acid, cystine, glutamic acid, glycine, proline, serine, and tyrosine. Possible accessory nutrient amino acids: Taurine, l-ornithine, l-carnitine
Life is an exercise in molecular synthesis and control. The programs, which determine what we are and how we function, are coded in DNA molecules, housed in the nucleus of every cell. The DNA code consists of strings of 64 alphabet characters that specify amino acids in-groups of three characters (codones). A single character is a base pair that is visualized as the rung on a ladder, twisted into a helix. The entire range of cellular procedures of life consists of stringing amino acids together. The DNA alphabet (blueprint) is first translated into enzyme synthesis. Enzymes, in turn, orchestrate and control the synthesis of all molecules (construction procedures). This is an elegant, simple plan that permits the evolution of great complexity.
Molecular synthesis takes the form: DNA---->RNA----> Enzyme Proteins
The amino acid sequence is read from the DNA molecule and transferred to the protein synthesis machinery by messenger RNA. Protein synthesis centers are Ribosomes that draw amino acids from the cellular pool into a sequence determined by messenger RNA. The ordered amino acids are then linked by enzymatic action to form a protein. The link between amino acids is as a peptide bond. The "Amino" of amino acids is a nitrogen-hydrogen group, NH2.
Every amino acid has NH2 at one end and COOH, the acid, at the other end. The peptide bond links the NH2 with the COOH like this: -CO-NH-OC-
When the peptide bond is made, a surplus of two hydrogen and one oxygen atom is removed - H2O, or water. We use a 3-letter abbreviation of the amino acid name to write an amino acid sequence which is the primary structure of a peptide or protein: Gly-Leu-Gly-Try-.is a 4 amino acid sequence. Short chains of amino acids are peptides; longer chains are polypeptides. Even longer chains are proteins. Peptides assume information characteristics at 3 or more AA lengths. As the AA chain elongates, its shape becomes more complex and more meaningful. A typical globular protein has about 350 amino acids. The long amino acid chains of proteins are folded into a shaped object. The shape is known as the tertiary structure of the protein.
Protein shape is information. The shape may determine where the protein can go in a cell or which biological membrane will let it pass. The shape determines its structural role. The shape of a protein is also its identity. Shape ID is recognized and remembered by the immune system and is the basis of the body's immune defense. A small error in the DNA code results in a large manufacturing error. The study of individual enzyme defects has given us insights into the control of molecular assembly. If a single gene, encoding the procedures for a single protein, is defective, the protein is missing or does not function properly.
Amino Acid Requirements.
The need for specific amino acids is difficult to determine. There is a wide range of needs and tolerances among different individuals. Amino acids appear to be relatively easy to obtain in adequate amounts, even on simple vegetarian diets with no meat, fish, eggs, or milk, if different vegetables are combined. Mixing a legume with a grain or with a tuber should provide a complete amino acid mixture, as well as a good variety of vitamins and minerals.
Protein-deficiency anxiety is not well founded in affluent countries. Some of the non-essential AA's may become essential if their synthesis is blocked by enzyme deficiencies. In order for protein synthesis to proceed, all the amino acids must be supplied at the same time. Since we are mammals, all mammalian proteins tend to have the same set of AAs as our own. Plant proteins may be deficient in lysine, threonine, and tryptophan. Vegetables should be combined to achieve a complete the AA set. Corn or maize, for example, is deficient in lysine, although many years of corn-breeding research have produced hybrid corns with increased lysine content. The substitution of the newer corn hybrids may eliminate protein malnutrition where corn is a staple.
Some patients on very limited diets (rice and a few vegetables alone, for example) remain well, at least for several months although their food may be appear to be deficient in essential AAs. A minimal diet presents minimal problems to one's metabolism. A protein deficient diet may be better tolerated than a protein excess diet. The missing amino acids are supplied from internal reserves as protein is recycled every day. If you look at RDA values for protein, you get the wrong idea that amino acid intake level has to the same as protein intake but we believe that a daily intake of 25 grams of free form amino acids will be adequate most of the time. RDA protein values are approximations based on eating food. The proteins in foods have to be digested into dipeptides and free amino acids before nutrients are available and protein digestion is incomplete Some percentage of food protein is wasted in the digestive tract.
The trick is that if amino acids arrive in high concentrations, the liver is obligated to destroy most of them; so that high protein intake is wasteful if you want the amino acids to be utilized as protein building blocks and as neurotransmitter substrates. You have to know that the body recycles amino acids an becomes every efficient when protein intake is low; the loss of amino acids can drop to about 2 grams per day. You have to know that amino acid proportioning is relevant to how amino acids are admitted to cells and how they are utilized. The concept of protein quality is used to express the idea that all the 9 essential amino acids have to be present before any of them can be used to make proteins.
Alpha Nutrition formulas contain a mixture of L-form amino acids.
On the positive side of the equation, if a completely available, precisely designed amino acid set is available, the total daily requirement is lower the RDA values for food protein intake. As a rule of thumb we recommend calculating the RDA protein requirement in grams and supplying 30 % to 50% of that value as Alpha AAX, a blend of amino acids (available separately in Alpha AAX or combined with other nutrients in Alpha ENF, Alpha PMX and Alpha DMX.)
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