BIOLOGY 2B03 Chapter Notes - Chapter 3: Ubiquitin Ligase, Protein Folding, Coiled Coil
6 Feb 2013
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Document Summary
A protein chain folds into a shape stabilized by noncovalent interactions between regions of the linear sequence. Function is derived from 3d structure and structure is derived by amino acid sequence. Size of a protein or polypeptide is reported as its mass in daltons or molecular weight (mw). Spatial arrangements resulting from the folding of localized parts of a polypeptide chain. In the absence of stabilizing noncovalent interactions, a polypeptide assumed a random coil structure. Alpha helices and beta sheets are the major internal supportive elements in proteins. The carbonyl oxygen atom of each peptide bond is hydrogen-bonded to the amide hydrogen atom of the amino acid four residues toward the c-terminus. The arrangement holds the backbone in a rodlike cylinder from which the side chains point outward. Hydrogen bonding between backbone atoms in adjacent b strands, within either the same polypeptide chaon or between different polypeptide chains, forms a b sheet.
