BCH 2333 Lecture Notes - Lecture 9: Dynamic Structures, Hydrophobic Collapse, Myosin
16 Dec 2017
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Document Summary
Describes the organization of subunits in a protein with multiple polypeptides. Same interactions that make motif and tertiary structure. Dimers: two of the same polypeptide subunits, has a two-fold plane of symmetry. Trimer: three of the same polypeptide subunits, three-fold plane of symmetry. Oligomeric protein is more stable than dissociated subunits: driving force for quaternary structure formation. Active site often made up of aa residues from different subunits. Hiv protease has to come together to be functional. Quaternary and tertiary structure is often affected by ligand (substrate or inhibitor) binding. Structures of proteins are not static - binding substrates or other proteins can cause 3d structure to change. Myosin needs to move in order for muscles to contract. Domains can move relative to each other: substrate binding, phosphorylation, etc. How structures adopt their tertiary and quaternary structures. Relatively low stability when folded to allow proteins to adopt alternate conformation.
