Biochem Quiz 7 Practice Questions and Answers.

Into what two groups are proteins usually classified into based on tertiary structure? What are the general characteristics of those two groups? - Answer Fibrous proteins and globular proteins; fibrous proteins have a single type of repeating secondary structure and form long, filamentous strands; globular proteins are compact, complex and often contain many secondary structure elements What are the major themes of fibrous protein tertiary structure? - Answer 1. single repeating secondary structure unit 2. hydrophobic residues predominate in the interior as well as outer surfaces of the protein 3. monomeric protein chain often pack together in complex supramolecular clusters What is the typical function of fibrous proteins? - Answer provide shape, support and structure in vertebrates To what family of structural proteins does alpha-keratin belong? - Answer Intermediate Filaments (IF) What is the predominant secondary structure of alpha-keratin? - Answer alpha-helix Describe the motif found in alpha-keratin. - Answer two alpha-helices that wrap around each other form a coiled coil motif; the helices are arranged in parallel, with their N-termini at the same end and the coil itself is twisted to follow a lefthanded path. "supertwisting" provides great deal of strength What is the predominant secondary structure of collagen? - Answer helices Describe the motif found in collagen. - Answer trimeric coiled coil called tropocollagen What is the predominant secondary structure of silk fibroin? - Answer beta-strands Describe the motif found in silk fibroin - Answer beta-sheets What amino acids are found in a repeating pattern in collagen. - Answer proline, glycine, modified proline (hydroxyproline)