BIOSC 1000: CHAPTER 3: AMINO ACIDS, PEPTIDES, AND PROTEINS

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12 Cards in this Set

Front	Back
enantiomers	nonsuperposable mirror images...true of all AA
polarity	tendency to interact with water at biological pH
Nonpolar, aliphatic R groups	Glycine (little hydrophobic interactions), Alanine, Proline (aliphatic side chain), Valine, Leucine, Isoleucine, and Methionine (nonpolar thioether group)
Aromatic R groups	Phenylalanine (least polar of the 3), Tyrosine (can H bond), and Tryptophan. Relatively nonpolar, all can participate in hydrophobic interactions
Polar, Uncharged R groups	contain functional groups that form H bonds with water: Serine, Threonine, Cysteine, Asparagine, and Glutamine (both found in proteins and easily hydrolyzed)
Positively charged (basic) R groups	o Hydrophilic at pH 7 o Lysine- has second primary amino group on thealiphatic chain o Arginine- pos charged guanidinium group o Histidine-aromatic imidazole group § pKa near neutrality and therefore can be chargedor uncharged at pH 7
Negatively Charged (Acidic) R groups	o Aspartate and Glutamate Each of which have second COO group
pKa	tendency of a group to give up a proton decreases 10x as the pKa increases by 1 unit
isoelectric point, pI	pH at which the net electric charge is zero
peptide	chains of amino acids
residue	part left over after losing a H atom from its amino group and the hydroxyl moiety from its carboxyl group
N-terminal	amino-terminal with free alpha-amino group