TY - BOOK AU - Branden, Carl and Tooze, John TI - Introduction to Protein Structure SN - 9780815323051 PY - 1999/// CY - New York PB - Garland Science T & F group KW - Protein N1 - Part I Basic Structural Principles 1. The Building Blocks Proteins are polypeptide chains The genetic code specifies 20 different amino acid side chains Cysteines can form disulfide bridges Peptide units are building blocks of protein structures Glycine residues can adopt many different conformations Certain side-chain conformations are energetically favorable Many proteins contain intrinsic metal atoms Conclusion Selected readings 2. Motifs of Protein Structure The interior of proteins is hydrophobic The alpha (a) helix is an important element of secondary structure The a helix has a dipole moment Some amino acids are preferred in a helices Beta (b) sheets usually have their b strands either parallel or antiparallel Loop regions are at the surface of protein molecules Schematic pictures of proteins highlight secondary structure Topology diagrams are useful for classification of protein structures Secondary structure elements are connected to form simple motifs The hairpin b motif occurs frequently in protein structures The Greek key motif is found in antiparallel b sheets The b-a-b motif contains two parallel b strands Protein molecules are organized in a structural hierarchy Large polypeptide chains fold into several domains Domains are built from structural motifs Simple motifs combine to form complex motifs Protein structures can be divided into three main classes Conclusion Selected readings 3. Alpha-Domain Structures Coiled-coil a helices contain a repetitive heptad amino acid sequence pattern The four-helix bundle is a common domain structure in a proteins Alpha-helical domains are sometimes large and complex The globin fold is present in myoglobin and hemoglobin Geometric considerations determine a-helix packing Ridges of one a helix fit into grooves of an adjacent helix The globin fold has been preserved during evolution The hydrophobic interior is preserved Helix movements accommodate interior side-chain mutations Sickle-cell hemoglobin confers resistance to malaria Conclusion Selected readings 4. Alpha/Beta Structures Parallel b strands are arranged in barrels or sheets Alpha/beta barrels occur in many different enzymes Branched hydrophobic side chains dominate the core of a/b barrels Pyruvate kinase contains several domains, one of which is an a/b barrel Double barrels have occurred by gene fusion The active site is formed by loops at one end of the a/b barrel UR - https://dasher.wustl.edu/bio5357/readings/branden-tooze-intro-protein-structure.pdf ER -