Amino Acids Flashcards
(25 cards)
What functional groups does the basic amino acid structure have?
- Amino
- Hydrogen
- Carboxylate group
- Side chain (R)
Which 5 amino acids are charged?
- Aspartate (-)
- Glutamate (-)
- Arginine (+)
- Lysine (+)
- Histidine (+)
What are Aspartate’s abreviations, structure, side chain, etc.?
- Asp, D
- pKa of 3.9
- Net negative charge at pH 7
What are Glutamate’s abreviations, structure, side chain, etc.?
- Glu, E
- pKa of 4.1
- Net negative at pH 7
What are Lysine’s abreviations, structure, side chain, etc.?
- Lys, K
- pKa of 10.5
- net positive at pH 7
What are Arginine’s abreviations, structure, side chain, etc.?
- Arg, R
- pKa of 12.5
- Net positive charge at pH 7
What are Histidine’s abreviations, structure, side chain, etc.?
- His, H
- pKa of 6.0
- The imidazole ring in His can be either positively charged or neutral depending on the environment
- Its ability to bind with different metals helps us with purification of proteins
What are hydrophilic amino acids?
- Serine
- Theronine
- Cysteine
- Asparagine
- Glutamine
What are Asparagine’s abreviations, structure, side chain, etc.?
- Asn, N
- Found on the surface of globular proteins
- Able to form hydrogen bonds
- Hydrophilic
- Similar to Aspartate
What are Glutamine’s abreviations, structure, side chain, etc.?
- Gln, Q
- Can form numerous hydrogen bonds
- Hydrophilic
- Structurally similar to Glutamate
What are Serine’s abreviations, structure, side chain, etc.?
- Ser, S
- Hydroxyl group in Ser forms hydrogen bonds and can be a substrate in proteins for kinase-mediated phosphorylation
- Hydrophilic (a bit hydrophobic from the CH2 center)
What are Threonine’s abreviations, structure, side chain, etc.?
- Thr, T
- Similar to Ser because of the hydroxyl group
- Hydroxyl group can form hydrogen bonds and may be phosphorylated by kinases
- Hydrophilic
What are Cysteine’s abreviations, structure, side chain, etc.?
- Cys, C
- Ionizable side chain has pKa 8.3
- Sulfhydryl can form disulfide bonds with other Cysteines (redox reaction) and they can form weak hydrogen bonds
- Only L-amino acid with an absolute configuration of R
Which amino acids can become phosphorylated and what allows this to happen?
- Kinases are enzymes that add a phosphate group to a protein
- This commonly occurs with Ser and Thr
- Phosphatase can then take the phosphate group off the protein
Which amino acids are hydrophobic?
- Glycine
- Alanine
- Proline
- Valine
- Leucine
- Isoleucine
- Methionine
What are Glycine’s abreviations, structure, side chain, etc.?
- Gly, G
- The smallest amino acid
- The most chemically neutral aa due to the hydrogen side chain
- Hydrophobic
What are Alanine’s abreviations, structure, side chain, etc.?
- Ala, A
- Very abundant in proteins
- Minimally hydrophobic
What are Proline’s abreviations, structure, side chain, etc.?
- Pro, P
- Cyclic ring limits the conformations that the proline can adopt
- Backbone nitrogen lacks a hydrogen which limits hydrogen bonding
- Hydrophobic
What are Valine’s abreviations, structure, side chain, etc.?
- Val, V
- Found in the hydrophobic core of globular proteins
- Small hydrophobic amino acid
What are Leucine’s abreviations, structure, side chain, etc.?
- Leu, L
- The most abundant amino acid in proteins
- Promotes hydrophobic interactions in the core of globular proteins
- Hydrophobic
What are Isoleucine’s abreviations, structure, side chain, etc.?
- Ile, I
- Found close to leucine and other hydrophobic amino acids
- Hydrophobic
What are Methionine’s abreviations, structure, side chain, etc.?
- Met, M
- The sulfur in Met is unreactive
- Always the starting amino acid
- Recognition amino acid
What are Phenylalanine’s abreviations, structure, side chain, etc.?
- Phe, F
- Phenyl ring is hydrophobic and chemically inert
- Good signaling amino acid
- Aromatic ring
What are Tyrosine’s abreviations, structure, side chain, etc.?
- Tyr, Y
- Ionizable hydroxyl griup is pKa 10.1
- It forms hydrogen bonds making Tyr an amphipathic amino acid
- Absorbs light at 280 nm
- Aromatic
