Post-translationally modified proteins and peptides

Capillary Electrophoresis of Post-Translationally Modified Proteins and Peptides... 

Beyond translation, proteins and peptides may be further modified by metabolic events within the cell. For instance, the hydroxyproline and hydroxylysine in collagen are formed from proltne and lysine that are hydroxyl-ated while they are part of the precursor protein molecule. A protein may also be post-translationally modified by cleavage of select bonds and/or by addition or subtraction of various kinds of groups. Insulin, for instance, is formed cleavage of a larger protnsultn molecule. Similar events occur in the activation of zymogens. 

S. Carganico, P. Rovero, J. A. Halperin, A. M. Papini, and M. Chorev, Building blocks for the synthesis of post-translationally modified glyeated peptides and proteins, J. Pept. Sci., 15 (2009) 67-71. 

Proteins are highly complex, folded polypeptide chains consisting of at least 20 different amino acids that are strung together in unique sequences, which relate to structure and function. Particular amino acids in proteins may be further modified post-translationally to contain a wide variety of covalent modifications normally found in native proteins. The way in which a peptide chain is wrapped and folded governs each amino acid s relative exposure to the outside environment, but post-translational modifications also can obscure the protein surface from easy access to the solvent environment. 

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