Amino acids Flashcards
Why do we need to eat amino acids
- they are the building blocks of proteins
- Animals can’t store nitrogen
- also used as an energy source to generate ATP
What two groups does every amino acid have
- Amino group which are the alpha-amino acids
- carboxylic acid group attached to the alpha carbon atom
Amphoteric
functioning as both an acid and base
- an example are amino acids
zwitterions
Molecules that contain both a negative and positive charge
Glycine
Also known as Gly or G
- only achiral amino acid
- smallest side chain with only 1H making it’s conformation the most flexible
- Functions as an inhibitory neurotransmitter and is the biosynthesis of purines and hemes
- nonpolar and aliphatic
Alanine
known as Ala or A
- rare
- nonpolar and aliphatic
Valine
Known as Val or V
- nonpolar and aliphatic
Leucine
Known as Leu or L
- In the skeletal muscle, leucine metabolism regulates protein biosynthesis.
-nonpolar and aliphatic
Isoleucine
known as Ile or I
- has a second chiral center
-nonpolar and aliphatic
proline
known as pro or P
- is unique in that it is a cyclic secondary amino acid.
- has the least conformation flexibility(rigid)
- known as helix breaker
- nonpolar and aliphatic
Methionine
known as Met or M
- Methionine has a thioether side chain but still is nonpolar and hydrophobic.
- codes for AUG
- nonpolar and aliphatic
Phenylalanine
Also known as Phe or F
- The aromatic ring of phenylalanine is comparable to that of benzene
- It is nonpolar and chemically unreactive
Tyrosine
Also known as Tyr or Y
- nonpolar
- biosynthesis of melanin, dopamine, epinephrine and norepinephrinev
How do aromatic rings in amino acids unique and what three amino are they?
They are nonpolar so they can absorb light in the ultraviolet region
- phenylalanine @260nm
- tyrosine @280nm
- tryptophan @280nm
Tryptophan
Also known as TRP or W
- Tryptophan contains the nonpolar and bulky, aromatic, indole side chain.
- Protonation of the indole nitrogen destroys the aromaticity of the indole ring. The indole side chain is fluorescent making tryptophan fluorescence very useful for studying protein structure.
- Tryptophan is the precursor for the biosynthesis of melatonin and serotonin
Lysine
Also known as Lys or K
- Basic
- contains butyl ammonium side chain
Histidine
Also known as His or H
- Basic
- imidazole functional group. The imidazole ring is aromatic.
- coordinate to metal ions such as zinc, iron, nickel, copper and magnesium
Arginine
Also known as Arg or R
- Basic
- contains a guanidino group at end of its ide chain
Aspartate
Also known as Asp or D
- Acidic Amino Acids, Negatively Charged
Glutamate
Also known as Glu or E
- Acidic Amino Acids,
- function as neurotransmitter and flavor enhancer
Asparagine
Also known as Asn or N
- Polar, uncharged amino acid
Glutamine
Also known as Gln or Q
- Polar, uncharged amino acid
- unionizable
- important for maintaining nitrogen balance in cells
- source of ammonia transport excess ammonia from the tissues to the liver
Serine
Also known as Ser or S
- Polar, uncharged amino acid
- similar to ethanol
Threonine
Also known as Thr or T
- Polar, uncharged amino acid
- contains a second chiral center
Cysteine
Also known as Cys or C
- Polar, uncharged amino acid
- Thiol side chain that is unionized
- sulfhydryl of cysteine coordinates to metal ions such as zinc, iron, nickel, copper and magnesium.
- Two cysteines in close proximity can be oxidized to form disulfide bonds.
- most abundant
What kind of reactions does cysteines participate in
biological redox reactions
-The disulfide bond can join two separate protein chains or crosslink two cysteines within the same chain
D pKa
3.90
E pKa
4.10
H pKa
6
K Pka
10.5
R pKa
12.5
C pKa
8.3
Y pKa
10.10
