Amino Acids, Peptides, and Proteins Flashcards
What is the general structure of amino acids, and what single amino acid is the exception?
Enantiomers Proline is the exception
What amino acids contain nonpolar, aliphatic R groups?
Glycine, alanine, proline, valine, leucine, isoleucine, methionine
What amino acids contain aromatic R groups?
Phenylalanine, tyrosine, tryptophan
What amino acids contain polar, uncharged R groups?
Serine, threonine, cysteine, asparagine, glutamine
What amino acids contain positively charged R groups?
Lysine, arginine, histidine
What amino acids contain negatively charged R groups?
Aspartate, glutamate
What is the only one of the aromatic amino acids with an ionizable side chain?
Tyrosine
What amino acid is responsible for most of the absorbance of ultraviolet light by proteins?
Tryptophan
What is the correlation of environmental pH on pKa?
As pH increases, pKa increases
In a titration curve, how do you calculate pI?
Take the first and second pKas and find the average
How are peptide bonds formed by condensation?
Two amino acids come together; one has a carboxy terminus and the other has an amino terminus. Loss of water allows the two amino acids to bond via a peptide bond.
Describe the planar peptide group
The carbonyl oxygen has a partial negative charge and the amide nitrogen has a partial positive charge, causing the molecule to have a dipole. This is a trans configuration
Characteristics of alpha-helix, cross linked by disulfide bonds
tough, insoluble protective structure of varying hardness and flexibility
Characteristics of beta conformation
Soft, flexible filaments
Characteristics of collagen triple helix
High tensile strength, without stretch
Name this uncommon amino acid
4-hydroxyproline
found in collagen
Name this uncommon amino acid
5-hydroxylysine
found in collagen
