lecture 27.2

lecture 27.2 - 27-27-1Organic Organic H BrownWilliam H...

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Unformatted text preview: 27-27-1Organic Organic ChemistryChemistryWilliam H. BrownWilliam H. BrownChristopher S. FooteChristopher S. FooteBrent L. IversonBrent L. Iverson27-27-2Amino AcidsAmino Acids& Proteins& ProteinsChapter 27Chapter 2727-27-3Polypeptides & ProteinsPolypeptides & Proteins◆In 1902, Emil Fischer proposed that proteins are long chains of amino acids joined by amide bonds to which he gave the name peptide bonds◆Peptide bond:Peptide bond:the special name given to the amide bond between the α-carboxyl group of one amino acid and the α-amino group of another27-27-4Serylalanine (Ser-Ala)Serylalanine (Ser-Ala)H2NHOOHHOCH2H2NOOHH CH3H2NNOHHOCH2HHCH3OHOSerine(Ser, S)Alanine(Ala, A)+Serylalanine(Ser-Ala, (S-A)peptide bond27-27-5PeptidesPeptides•peptide:peptide:the name given to a short polymer of amino acids joined by peptide bonds; they are classified by the number of amino acids in the chain•dipeptide:dipeptide:a molecule containing two amino acids joined by a peptide bond•tripeptidetripeptide:a molecule containing three amino acids joined by peptide bonds•polypeptidepolypeptide:a macromolecule containing many amino acids joined by peptide bonds•proteinprotein:a biological macromolecule of molecular weight 5000 g/mol of greater, consisting of one or more polypeptide chains27-27-6Writing PeptidesWriting Peptides•by convention, peptides are written from the left, beginning with the free -NH3+group and ending with the free -COO-group on the rightH3NOHNHOHNCOO-O-OC6H5O+C-terminalamino acidN-terminalamino acidSer-Phe-Asp27-27-7Writing PeptidesWriting Peptides•the tetrapeptide Cys-Arg-Met-Asn•at pH 6.0, its net charge is +1HNNHOHNO-OOONH2SCH3NHNH2+H2NOH3NSHC-terminalamino acidN-terminalamino acidpKa 12.48pKa 8.00+27-27-8Primary StructurePrimary Structure◆Primary structure:Primary structure:the sequence of amino acids in a polypeptide chain; read from the N-terminal amino acid to the C-terminal amino acid◆Amino acid analysis•hydrolysis of the polypeptide, most commonly carried...
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This note was uploaded on 03/30/2008 for the course CHEM 262 taught by Professor Forbes during the Spring '08 term at UNC.

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lecture 27.2 - 27-27-1Organic Organic H BrownWilliam H...

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