Amino Acid Structure Flashcards
Most amino acids are ____ (alpha or beta)?
a-amino acids
Which are the 7 nonpolar AAs?
Glycine (Gly) Alanine (Ala) Proline (Pro) Valine (Val) Leucine (Leu) Isoleucine (Ile) (sometimes methionine (Met)
Which are the 7 polar, uncharged AAs?
Serine (Ser) Threonine (Thr) Asparagine (Asn) Glutamine (Gln) Cysteine (Cys)
Which are the 2 negatively charged AAs?
Aspartate (Asp)
Glutamate (Glu)
Which are the 3 positively charged AAs?
Lysine (Lys)
Arginine (Arg)
Histidine (His)
Which are the 3 aromatic AAs?
Phenylalanine (Phe)
Tyrosine (Tyr)
Tryptophan (Trp)
What are the ionizable groups of AAs and their pKa’s?
NH3+ (pKa 9)
COO- (pKa 2)
When pH = pKa
[A] = [HA]
ie concentration of conjugate base = concentration of conjugate acid
When pH > pKa
Less H+ ions
[A-] > [HA]
ie [COO-] > [COOH] or [NH2] > [NH3+]
When pH < pKa
More H+ ions
[A-] < [HA]
ie [COO-] < [COOH] or [NH2] < [NH3+]
Zwitterion
neutral molecule with negative and positive charge (they cancel each other)
pI is?
pH at which there is no net charge
What are the post-translation modifications to AAs in proteins?
- Carbohydrate Addition
- Lipid Addition
- Regulation
- Modified AAs
What is Carbohydrate Addition?
Adding Carbohydrate to the OH groups of AAs eg serine (O-linked) or to the N in the amide group eg asparagine (N-linked)
What is Lipid Addition?
Covalently attaching lipid moieties to proteins
