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Medical Term:


Pronunciation: pro'ten, proo'te-in


Macromolecules consisting of long sequences of a-amino acids [H2N–CHR–COOH] in peptide (amide) linkage (elimination of H2O between the a-NH2 and a-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 a-amino acids (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. protos, first, + -in]

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