BIOC 2580 Lecture Notes - Lecture 7: Beta Barrel, Alpha Helix, Lactate Dehydrogenase
9 Jan 2017
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Document Summary
Most proteins are folded into a unique 3d tertiary structure, which is required for their function. Denaturation unfolds proteins, unfolded form may be unstructured or aggregated. Protein"s function is typically lost on denaturation. When purifying proteins to study them, we usually try to avoid denaturation. Tertiary structure is the overall pattern of folding of the whole polypeptide chain. The simplest possible tertiary structure is continuous secondary structure. Collagen (tendon, bone and connective tissue) has a unique triple-helix structure. Collagen structure requires sequence with repeating units of three amino acids -gly-pro-x- Secondary structure is rigid, so these are fibrous proteins. Most proteins are globular: this requires the polypeptide to fold back on itself. Folding requires breaks in secondary structure, which is rigid. Clusters of 2-3 secondary structure breakers (glu, pro, asn, asp or ser; gpnds) in a run of 4 aas. Allows for flexible loops and turns where polypeptide can change direction to allow folding.
