Amino Acid Structures and Properties Flashcards
What is the average weight of one amino acid?
110g/mol or 110 Da
What is the only achiral amino acid?
Glycine
What are the basic building blocks of proteins?
Amino acids
How many types of amino acids can our body encode for?
20
What is the basic structure of an amino acid.
It has a carboxylic acid, hydrogen, amine group, and R side chain all attached to an Alpha carbon.
Are all of the chiral amino acids L-amino or D-amino acids? (based on the rotation of plane-polarized light)
L-amino (Living)
Which chiral amino acid is the only one with a R configuration? (based on structure)
Cysteine
What is a tetrapeptide?
A protein formed by 4 amino acids
Define a chiral center.
It is a carbon with 4 different substituents and has superimposable mirror images (enantiomers). It can also rotate plane polarized light.
Do most amino acids have an R or S configuration?
S
Define aliphatic amino acids
hydrocarbon side groups
How many non-polar and non-aromatic amino acids are there and what are they?
7 Glycine (Gly) G Alanine (Ala) A Valine (Val) V Leucine (Leu) L Isoleucine (Ile) I Methionine (Met) M Proline (Pro) P
What makes methionine unique in the non-polar and non-aromatic group?
It is one of two amino acids with a Sulfur (S) atom. It is also found in eggs and is involved in DNA methylation.
Why is proline unique?
It is the only amino acid that has a cyclic component that links back with the amino acid itself. The N in the amine group is part of proline’s side chain. It is rarely found in the middle of regular secondary structure of proteins because it has the ability to break the secondary structure up by introducing proline kinks. Common in turns between peptide strands in beta-pleated sheets.
How many non-polar and aromatic amino acids are there and what are they?
3
Phenylalanine (Phe) F - found in aspartame
Tyrosine (Tyr) Y
Tryptophan (Trp) W -precursor of serotonin and melatonin
What is aspartame?
Artificial sweetener
What is a precurser?
It is a substance from which another is formed, especially by metabolic reaction.
How many polar uncharged amino acids are there and what are they?
5 Serine (Ser) S - targeted by phosphorylation, primary -OH Threonine (Thr) T - secondary -OH Asparagine (Asn) N - amide Glutamine (Gln) Q - amide Cysteine (Cys) C
Why is cysteine a unique amino acid?
It is the only chiral amino acid with and R configuration. It is one of two amino acids with a sulfur atom. It contains a thiol group S-H. Two cysteine residues can for covalent disulfide bonds which are very important in tertiary structure of protein.
How many positively charged/basic amino acids are there and what are they?
3
Lysine (Lys) K
Arginine (Arg) R - most basic amino acid
Histidine (His) H - uncharged in physiological conditions
How many negatively charged/acidic amino acids are there and what are they?
2 Aspartic Acid (Asp) D - helps make aspartame Glutamic Acid (Glu) E - important neurotransmitter
What is a bronsted-lowry base
A proton acceptor
What is a bronsted-lowry acid
A proton donor
What is a proline kink?
How proline breaks up the helical and sheet motifs of secondary structure of proteins.
