Rare Amino Acids 4-Hydroxyproline,5-hydroxylysine found in collagen胶原， D-Glutamic acid in cell walls of bacteria. D-Serine in earthworms. y-Aminobutyric acid,a neurotransmitter. B-Alanine,constituent of the vitamin pantothenic acid泛酸
Rare Amino Acids ◼4-Hydroxyproline, 5-hydroxylysine found in collagen胶原 . ◼D-Glutamic acid in cell walls of bacteria. ◼D-Serine in earthworms. ◼-Aminobutyric acid, a neurotransmitter. ◼-Alanine, constituent of the vitamin pantothenic acid泛酸
L-amino acids are the natural form found in proteins "CORN"to the left L-amino acid “CDRN”to the right=D-amino acid PROTEINS ARE LEFTISTS!! Amino acids are tetrahedral structures
Stereochemistry of a-Amino Acids COOH CHO COOH H-N HO H cH,H】 H H COOH CHO COOH H2N H HO- H H2N- H CH3 CH2OH R (S)-alanine L-(-)-glyceraldehyde an L-amino acid (L-alanine) (S)configuration
Stereochemistry of -Amino Acids
Gabriel-Malonic Ester Synthesis COOE (1)NaOEr H,0 -CH -C-CH,CH,SCH. (2)CI-CH,CH,SCH, heat H.N-C-CH,CH,SCH COOEt COOEt COOH (D,L)-methionine (50%) Copyright2005 Pearson Prentice Hall,Inc. The amino group is protected as amide. The carboxylic acid group is protected as an ester. The a position is further activated by the additional temporary ester group
Gabriel-Malonic Ester Synthesis ◼The amino group is protected as amide. ◼The carboxylic acid group is protected as an ester. ◼The position is further activated by the additional temporary ester group
4.Strecker Synthesis +NH3 H20 H30 CH,一C一H+NH,+HCN CH,-C-H CH,一C-H C=N COOH acetaldehyde a-amino propionitrile (D,L)-alanine (60%) First known synthesis of amino acid,1850. ■One-pot RXN Aldehyde reaction with NH3 yields imine. Cyanide ion attacks the protonated imine. Resulting a-amino nitrile is hydrolyzed to a carboxylic acid
4. Strecker Synthesis ◼First known synthesis of amino acid, 1850. ◼One-pot RXN ◼Aldehyde reaction with NH3 yields imine. ◼Cyanide ion attacks the protonated imine. ◼Resulting -amino nitrile is hydrolyzed to a carboxylic acid