Amino Acids Flashcards
the primary structure of a protein
determined exclusively by the sequence of amino acids contained within the peptide
amino acids are comprised of which three groups
an amino group (-NH2)
a carboxyl group (-COOH)
a side chain (an R group)
peptide bond
the joining of the carboxyl group of one amino acid to the amino group of its neighboring amino acid
occurs via a dehydration reaction, in
which a water molecule is removed during the process of bond formation
the ends of the polypeptide
one end (the N-terminus) has an amino group and the other end (C-terminus) has a carboxyl group
these ends do not participate in peptide bond formation
aliphatic
amino acids with side chains that only contain the presence of carbon and hydrogen atoms
nonpolar, aliphatic amino acids
glycine (Gly, G) alanine (Ala, A) proline (Pro, P) valine (Val, V) leucine (Leu, L) isoleucine (Ile, I)
[LIVe the GAP]
nonpolar amino acids
leucine (Leu, L) isoleucine (Ile, I) valine (Val, V) glycine (Gly, G) alanine (Ala, A) proline (Pro, P) tryptophan (Trp, W; aromatic) methionine (Met, M; contains sulfur) phenylalanine (Phe, F; aromatic)
[in summer, we LIVe the GAP With More Friends]
achiral amino acid
glycine (Gly, G), which is also the smallest
which amino acid has a secondary amino group
proline (Pro, P), the secondary amino group makes the side chain large and awkward
branched amino acids
a subgroup of the nonpolar, aliphatic amino acids
valine (Val, V)
leucine (Leu, L)
isoleucine (Ile, I)
uncharged polar amino acids
asparagine (Asn, N) [have n’s for not charged and Nitrogen]
glutamine (Gln, Q) [have n’s for not charged and Nitrogen]
cysteine (Cys, C)
tyrosine (Tyr, Y)
serine (Ser, S)
threonine (Thr, T)
[a boring and cold subject is N Quigley’s CYST]
common targets of post-translation modification
serine (Ser, S)
threonine (Thr, T)
tyrosine (Tyr, Y)
typically modified by phosphorylation and glycosylation
phosphorylation
the addition of phosphate group; occurs at the –OH within the side chain and is commonly used as a means to regulate the activity of a protein through conformational changes mediated by the negative charge of the organic phosphate group.
glycosylation
the addition of carbohydrate group; occurs at the –OH group within the side chain and is a common post-translational modification used for secreted proteins
acidic amino acids
aspartate (Asp, D; aspartic acid)
glutamate (Glu, E; glutamic acid)
DE acidic amino acids (found with a negative charge at physiological pH (~7.4) due to the deprotonation of the carboxylic acid (-COOH) group on the side chain
basic amino acids
arginine (Arg, R)
lysine (Lys, K)
histidine (His, H)
found with a positive charge on the side chain at physiological pH (~7.4)
electrostatic interactions
ionic bonds which acidic and basic amino acid groups can form with members of their oppositely charged group
which amino acid is acetylated during post-translation modification
lysine (Lys, K); the acetylation of lysine prevents its ionization and thus turns a positively charged residue into one with a neutral charge
the interaction of histones (high lysine content) with negatively charged DNA is partially regulated through the acetylation of lysine residues
Histone acetyltransferase (HAT)
the enzyme responsible for histone acetylation
aromatic amino acids
tyrosine (Tyr, Y)
phenylalanine (Phe, F)
tryptophan (Trp, W)
contain large ring structures in their side chains
most hydrophobic aromatic amino acid
phenylalanine, which commonly forms hydrophobic interactions with neighboring phenylalanine residues
the flat nature of the ring structure allows for close ordered packing of these residues
and the exclusion of water molecules
Tyr and Trp have -OH and -NH groups which can hydrogen bond
sulfur containing amino acids
methionine (Met, M)
cysteine (Cys, C)
which amino acid is the first amino
acid encoded in the mRNA of a polypeptide
methionine (Met, M); can be found elsewhere in the sequence too!
which amino acid can serve as a donor of methyl (-CH3) groups to other cellular molecules
methionine (Met, M)
which amino acid can form disulfide bonds
cysteine (Cys, C); has a thiol group (-SH) which forms the disulfide bond through an oxidation rxn with other cysteines to result in a cystine residue (no middle “e”)
Aldehyde
Functional group with a carbonyl group (C=O) and a -H bond
Ketone
Functional group with a carbonyl group (C=O) and two carbon-containing groups on each side of the carbonyl carbon
Carboxylic acid
Functional group with a carbonyl group (C=O) and a hydroxyl group
Which aromatic amino acid can serve as functional precursors to different hormones and can play a role in stabilizing protein structures?
Tyrosine (Tyr, Y)
