pro·tein (p), (prō'tēn, prōo'tē-in), Do not confuse this word with protean.
Macromolecules consisting of long sequences of α-amino acids [H2N-CHR-COOH] in peptide (amide) linkage (elimination of H2O between the α-NH2 and α-COOH of successive residues). Protein is three fourths of the dry weight of most cell matter and is involved in structures, hormones, enzymes, muscle contraction, immunologic response, and essential life functions. The amino acids involved are generally the 20 α-amino acids (for example, glycine, l-alanine) recognized by the genetic code. Crosslinks yielding globular forms of protein are often effected through the -SH groups of two l-cysteinyl residues, as well as by noncovalent forces (hydrogen bonds, lipophilic attractions, etc.).
[G. prōtos, first, + -in]
protein (prō′tēn′, -tē-ĭn)
Any of a group of complex organic macromolecules that contain carbon, hydrogen, oxygen, nitrogen, and usually sulfur and are composed of one or more chains of amino acids. Proteins are fundamental components of all living cells and include many substances, such as enzymes, hormones, and antibodies, that are necessary for the proper functioning of an organism. They are essential in the diet of animals for the growth and repair of tissue and can be obtained from foods such as meat, fish, eggs, milk, and legumes.
pro′tein·a′ceous (prōt′n-ā′shəs, prō′tē-nā′-), pro·tein′ic (prō-tē′nĭk)(prō-tē′nəs), pro·tein′ous (prō-tē′nəs) adj.
protein Biochemistry A large molecule consisting of a long chain or sequence of amino acids with a general formula of H2N–CHR–COOH–aka alpha amino acids, joined in a peptide likage; after water, proteins are the major cell constituent, and are critical for all biological structures–eg, organelles, mitochondria, enzymes and functions–eg, growth, development, immune function, motility Types Hormones, enzymes, antibodies
Macromolecules consisting of long sequences of α-amino acids [H2
N-CHR-COOH] in peptide (amide) linkage (elimination of H2
O between the α-NH2
and α-COOH of successive residues). Protein is three fourths of the dry weight of most cell matter and is involved in structures, hormones, enzymes, muscle contraction, immunologic response, and essential life functions. The amino acids involved are generally the 20 α-amino acids (glycine, l
-alanine) recognized by the genetic code. Cross-links yielding globular forms of protein are often effected through the -SH groups of two sulfur-containing l
-cysteinyl residues, as well as by noncovalent forces (e.g., hydrogen bonds, lipophilic attractions).
[G. prōtos, first, + -in]
protein a large complex molecule (M W from 10 000 to more than 1 million) built up from AMINO ACIDS joined together by PEPTIDE BONDS. All proteins contain carbon, hydrogen, oxygen and nitrogen and most contain sulphur. Proteins are produced in the cytoplasm at the ribosomes (see PROTEIN SYNTHESIS and begin as long, unbranched POLYPEPTIDE CHAINS, the primary structure. All protein molecules undergo a physical rearrangement to give a secondary structure. The most common type of shape is alpha-helix (right-handed) where the coils are held in place by hydrogen bonds. Some proteins, such as keratin, remain at this stage. An alternative secondary structure is beta-pleatingwhere parallel polypeptide chains are cross-linked by hydrogen bonds forming an extremely tough structure, as in silk. Proteins with these relatively simple two-dimensional secondary structures are called fibrous proteins.
Some proteins undergo even more complex folding, where the secondary structure is arranged into a three-dimensional tertiary structure forming ‘globular’ proteins held together by forces between side groups. Such molecules are, for example, ENZYMES, ANTIBODIES, most blood proteins, and MYOGLOBIN. finally, globular proteins can be composed of two or more polypeptide chains loosely bonded together, for example, HAEMOGLOBIN, giving a quaternary structure.
A substance produced by a gene that is involved in creating the traits of the human body, such as hair and eye color, or is involved in controlling the basic functions of the human body, such as control of the cell cycle.
Complex organic molecule composed of various combinations of any of twenty α-amino acids linked in a genetically controlled linear sequence into one or more peptide chains. Proteins are present in every living cell and form an essential constituent of cells. They are essential in many functions, such as growth and repair of tissue, transport of molecules throughout the body (e.g. haemoglobin to carry oxygen), as enzymes to catalyse biochemical reactions, immunological responses, muscle contraction (with actin and myosin), signalling (e.g. insulin which transmits a signal from a cell where it is synthesized to other cells in other tissues), or as antibodies by binding to target receptors. Many of the twenty amino acids are produced by the body. However, nine of these have to be obtained in food.
Macromolecules consisting of long sequences of α-amino acids; represents three fourths of dry weight of most cell matter; involved in structures, hormones, enzymes, muscle contraction, immunologic response, and essential life functions.
[G. prōtos, first, + -in]
Patient discussion about protein
Q. I get about 190 grams of protein a day. Is that too much protein? Have you ever seen a guy living only for food? No? Here I am. I get about 190 grams of protein a day. Is that too much protein? My weight is 183 pounds.
A. this is a good amount, just make sure that you get the majority of it from real foods and not from powders and bars.
Q. Does the cooking have a negative effect on the protein content of the food? I have heard that high temperatures cooking breaks the protein, so does the cooking have a negative effect on the protein content of the food?
A. Yes. Proteins can be denatured by heat, but only when the protein structure is delicate or is exposed to extremely high temperatures for long time. You must remember that breaking of protein is the physical-chemical process where the physical or chemical structure of a protein is rearranged. So cooking will not reduce on the nutritive value of the food until it’s cooked at cooking temperatures.
Q. Is it true that Casein protein can cause Cancer, or is harmful to the human body? Someone left a comment on my blog about Casein protein being bad for the body and that it could lead to Cancer. Is this true?
A. I am not familiar with such information, Casein is a protein that is found in large amounts in breastmilk and milk products replacements for babies and as far as I know it has no such affect.More discussions about protein