Unformatted text preview: • tertiary: tridimensional structure made by runs of secondary structure elements (helices and sheets). Can be stabilized by disulfide bonds (-SH + HS- = -S-S-), and by other, non-covalent bonds (H, ionic, etc) • quaternary: separate, two or more, polypeptides come together and form a complex proteins. Stabilized by H, ionic, hydrophobic, van der Waals, disulfide bonds. • denaturation: certain conditions such as heat, acid or base, urea treatments cause loss of structure. Examples: cooking egg white or meat • proteins are immensely flexible compounds that can assume virtually any role and shape (*) important point about Asn. The -NH2 group of Asn can ionize only in strong acid. So, Asn is effectively a "non-charged" amino acid. By contrast, the -COOH of aspartic acid (Asp) is mostly ionized under normal, pH neutral conditions....
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- Spring '09