Lecture 4: Amino Acids Flashcards
What is the only amino acid that is not a tetrahedral
Proline
Which symbol do all proteins contain L or D
L (l and d are used for light rotation).
This is based on the configuration of glyceraldehyde.
What are the non-polar, aliphatic amino acids?
Glycine, Alanine, Proline, Valine, Leucine, Isoleucine, Methionine
What is the absorbance maxima for aromatic amino acids?
Which show the strongest absorbance?
275-280 nm
Tryptophan > Tyronsine > Phenylalanine
What are the non-polar aromatic amino acids?
Phenylalanine, Tyrosine, Tryptophan
What is Beer-Lambert law?
A = c e l
a = absorbance c = concentration e = molar absorptivity l = length of cuvette
What are the polar uncharged amino acids?
Serine, threonine, cysteine, asparagine, glutamine
When a disulfide bridge is being formed is cysteine being reduced or oxidized?
Now Cystine
Losing 2H+ and 2e-
Oxidized
What are the positively charged amino acids
Lysine, Arginine, and Histidine
What are the negatively charged amino acids?
Aspartate, Glutamate
a-carboxy group is (more/less) acidic than carboxylic acids
a-amino group is (more/less) basic than an amine
Much more acidic
Slightly less basic
What is a zwitterion?
A single molecule with both a positive and negative charge
Draw an amino acid going through cation, zwitterion, to anion
What is an isoelectric point (pl)?
pKa of zwitterion
- least soluble in water
- does not migrate in electric field
What are the buffer regions of an amino acid?
The half equivalent points
What does the condensation of two amino acids create?
dipeptide
What is the pl of this peptide
2.945
