Chapter 26.ppt - Chapter 26:Biomolecules Amino Acids Peptides and Proteins Based on McMurry\u2019s Organic Chemistry 6th edition \u00a92003 Ronald Kluger

Chapter 26.ppt - Chapter 26:Biomolecules Amino Acids...

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Based on McMurry, Organic Chemistry, Chapter 26 , 6th edition, (c) 2003 1 Chapter 26:Biomolecules: Amino Acids, Peptides, and Proteins Based on McMurry’s Organic Chemistry, 6th edition ©2003 Ronald Kluger Department of Chemistry University of Toronto
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Based on McMurry, Organic Chemistry, Chapter 26, 6th edition, (c) 2003 2 Proteins – Amides from Amino Acids Amino acids contain a basic amino group and an acidic carboxyl group Joined as amides between the NH 2 of one amino acid and the CO 2 H the next Chains with fewer than 50 units are called peptides Protein: large chains that have structural or catalytic functions in biology
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Based on McMurry, Organic Chemistry, Chapter 26, 6th edition, (c) 2003 3 26.1 Structures of Amino Acids In neutral solution, the COOH is ionized and the NH 2 is protonated The resulting structures have “+” and “-” charges (a dipolar ion , or zwitterion ) They are like ionic salts in solution
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Based on McMurry, Organic Chemistry, Chapter 26, 6th edition, (c) 2003 4 The Common Amino Acids 20 amino acids form amides in proteins All are -amino acids - the amino and carboxyl are connected to the same C They differ by the other substituent attached to the carbon, called the side chain, with H as the fourth substituent except for proline Proline, is a five-membered secondary amine, with N and the C part of a five-membered ring
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Based on McMurry, Organic Chemistry, Chapter 26, 6th edition, (c) 2003 5 Abbreviations and Codes Alanine A, Ala Arginine R, Arg Asparagine N, Asn Aspartic acid D, Asp Cysteine C, Cys Glutamine Q, Gln Glutamic Acid E, Glu Glycine G, Gly Histidine H, His Isoleucine I, Ile Leucine L, Leu Lysine K, Lys Methionine M, Met Phenylalanine F, Phe Proline P, Pro Serine S, Ser Threonine T, Thr Tryptophan W, Trp Tyrosine Y, Tyr Valine V, Val
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Based on McMurry, Organic Chemistry, Chapter 26, 6th edition, (c) 2003 6 Learning the Names and Codes The names are not systematic so you learn them by using them (They become your friends) One letter codes – learn them too If only one amino acid begins with that letter, use it ( C ys , H is , I le , M et , S er , V al) If more than one begins with that letter, the more common one uses the letter ( A la , G ly , L eu , P ro , T hr) For the others, some are phonetic: F enylalanine, a R ginine, t Y rosine Tryp has a double ring, hence W Amides have letters from the middle of the alphabet ( Q Think of “ Q tamine” for glutamine; asparagine -contains N “Acid” ends in D and E follows (smallest is first: aspartic aci D , Glutamic acid E )
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Based on McMurry, Organic Chemistry, Chapter 26, 6th edition, (c) 2003 7 Neutral Hydrocarbon Side Chains
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Based on McMurry, Organic Chemistry, Chapter 26, 6th edition, (c) 2003 8 -OH, SH (Nucleophiles) and -S-CH 3 Cysteine C, Cys Methionine M, Met Serine S, Ser Threonine T, Thr Tyrosine Y, Tyr
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Based on McMurry, Organic Chemistry, Chapter 26, 6th edition, (c) 2003 9 Acids and Amides Aspartic acid D, Asp Glutamic Acid E, Glu Asparagine N, Asn Glutamine Q, Gln
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Based on McMurry, Organic Chemistry, Chapter 26, 6th edition, (c) 2003 10 Amines Arginine R, Arg Histidine H, His Lysine K, Lys Tryptophan W, Trp
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