Naturally occurring damino acids exist in some

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Unformatted text preview: side chains make? Glutamine Greek nomenclature for carbon atoms in amino acids •  They are assigned sequenGal leaers in the Greek alphabet, beginning with the alpha carbon. Stereochemistry of Amino Acids •  α ­carbon is a chiral center (asymmetric C, 4 different subsGtuents) – except glycine •  2 possible stereoisomers that are nonsuperimposable mirror images (enan+omers), D and L •  L ­amino acids = the naturally occurring enanGomers found in all proteins. •  Naturally occurring D ­amino acids exist in some bacterial cell wall pepGde structures, in some pepGde anGbioGcs, etc., but not generally in proteins. •  Only right ­handed helices observed in proteins Life is Asymmetric BiosyntheGc processes produce pure stereoisomers Biomolecules are asymmetric •  Ordinary chemical synthesis produces racemic mixture (equal amounts of each enanGomer) •  Many drugs are chemically synthesized as racemic mixture, but only one enanGomer has biological acGvity (ex. ibuprofen, thalidomide) Amino Acid names are abbreviated alanyltyrosylaspartylglycine – never used 3 leaer code 1 leaer code AYDG Full name Cysteine HisGdine Isoleucine Methionine Serine Valine Alanine Glycine Leucine Proline Threonine Arginine Phenylalanine Tyrosine Tryptophan AsparGc Acid Asp...
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