problem set 3-1

problem set 3-1 - Chromatography in the presence of 6 M...

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1) What are the non-covalent interactions that hold proteins/peptides together? 2) Using one sentence for each, describe the four higher levels of protein structure. 3) Which amino acid is responsible for distorting an alpha helix? 4) There are two types of beta pleated sheets in the secondary structure of proteins. Hydrogen bonding is significantly bent in which of these two orientations? 5) The central rod domain of a keratin protein is approximately 312 residues in length. What is the length (in Angstroms) of the keratin rod domain? If this same peptide segment were a true alpha helix, how long would it be? If the same segment were a beta sheet, what would its length be? 6) Proline is the amino acid least commonly found in alpha helices but most commonly found in beta turns. Why? 7) A new protein of unknown structure has been purified. Gel filtration chromatography reveals that the native protein has a molecular weight of 240,000. Chromatography in the presence of 6 M guanidine hydrochloride yields only a peak for a protein of molecular weight 60,000.
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Unformatted text preview: Chromatography in the presence of 6 M guanidine hydrochloride and 10 mM mercaptoethanol yields peaks for proteins of 34,000 and 26,000 molecular weight. Explain what can be determined about the structure of this protein from these data. 9) Which amino acids would be capable of forming H bonds with a lysine residue in a protein? 10) Poly –L-glutamate adopts an alpha helical structure at low pH but becomes a random coil above pH 5. Explain this behavior. ANSWERS 1) H bonding, hydrophobic interactions, Van der Waals forces, electrostatic interactions. 2) Primary – this is the amino acid sequence, secondary – residue by residue building of the backbone conformation, tertiary – the three dimensional conformation of a polypeptide or single protein chain, quarternary – the three dimensional structure of a multi-subunit protein. 3) proline – it puts a “kink” in the alpha helix due to restricted stearics of the structure 4) parallel beta sheets. 5) 6) 7) 9) 10)...
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This note was uploaded on 04/17/2011 for the course PHY 7b taught by Professor Taylor during the Winter '08 term at UC Davis.

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problem set 3-1 - Chromatography in the presence of 6 M...

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