Module 01 - Section 02 Flashcards
Introduction to Amino Acids
What is the difference between peptide, polypeptide and protein?
Often used interchangeably, but generally;
peptide = <10 amino acids
polypeptide = <100 amino acids
polypeptide chain = any size
protein= large macromolecule that can be composed of one or more polypeptide chains
What distinguishes an amino acid from another?
The R-group, also called side chain
How are Amino Acids classified? (2+5)
(1) Nonpolar
(a) Aliphatic
(b) Aromatic
(2) Polar
(a) Uncharged
(b) Negatively charged
(c) Positively charged
What are the Aliphatic amino acids? (7)
GAVLIMP
Glycine, Alanine, Valine, Leucine, Isoleucine, Methionine, Proline
What are the Aromatic amino acids? (3)
Phenilalanine, Tryptophan, Tyrosine
What are the Uncharged Amino acids? (5)
STNCQ (“Stinky Q”)
Cysteine, Asparagine, Glutamine, Serine, Threonine
What are the negatively charged amino acids? (2)
Aspartate, Glutamate
What are the positively charged amino acids? (3)
Lysine, Arginine, Histidine
Which amino acid is the smallest?
Glycine
Which nonpolar aliphatic contribute the least to hydrophobic effects?
Glycine
Which amino acids are isomers of each other?
Leucine and Isoleucine, they have the same number of carbon and hydrogen atoms but are arranged differently
Which amino acids have simple hydrocarbons chains? (4)
Alanine, Valine, Leucine, Isoleucine
3-letter abre: Gly
Glycine
1-letter: G
Glycine
3-letter: Ala
Alanine
1-letter: A
Alanine
3-letter: Val
Valine
1-letter: V
Valine
3-letter: Leu
Leucine
1-letter: L
Leucine
3-letter: Ile
Isoleucine
1-letter: I
Isoleucine
Which amino acid contains a thioether group in its side chain?
Methionine
3-letter: Met
Methionine
1-letter: M
Methionine
Which is the only amino acid whose side chain connects to its amino group?
Proline
What is special about proline?
Its side-chain is connected to its amino group. The resulting 5-membered ring causes proline to be very rigid and thus limits its possible conformations
3-letter: Pro
Proline
1-letter: P
Proline
3-letter: Phe
Phenylalanine
1-letter: F
Phenylalanine
3-letter: Tyr
Tyrosine
1-letter: Y
Tyrosine
3-letter: Trp
Tryptophan
1-letter: W
Tryptophan
Which is the most hydrophobic of the Aromatic Amino Acids?
Phenylalanine
Which Aromatic Amino acids can form hydrogen bonds? (2) which moieties are involved?
Tyrosine, Hydroxyl group -OH
Tryptophan, Nitrogen
Which Amino acids are able to absorb UV light?
Aromatic Amino Acids – phenylalanine less than tryptophan and tyrosine
Which property of which amino acids is used by researches in the characterization of proteins?
Absorption of 280nm wavelength light by the aromatic rings of aromatic amino acids
Which type of amino acids can interact extensively with water, or with atoms in other side chains through hydrogen bonds?
Polar uncharged amino acids
3-letter: Cys
Cysteine
1-letter: C
Cysteine
3-letter: Asn
Asparagine
1-letter: N
Asparagine
3-letter:Gln
Glutamine
1-letter: Q
Glutamine
3-letter: Ser
Serine
1-letterL S
Serine
3-letter: Thr
Threonine
1-letter: T
Threonine
Which amino acid residues can be oxidized to form a disulfide bond?
Cysteine
Which Amino Acid contains a sulfhydryl group?
Cysteine
What bond connects two regions of one or more polypeptide chains within a protein and acts as a molecular cross-brace to enhance protein stability?
Disulfide bond
What is a nucleophile?
Reactant that provides a pair of electrons to form a new covalent bond
Name the 2 roles of Cysteine in proteins
(1) Enhance protein stability through disulfide bonds
(2) Important in catalytic functions of many enzymes, as the deprotonated -SH is a good nucleophile
Which amino acids’ side chains contain an amide group that can act as both a donor or acceptor of electrons? (2)
Asparagine & Glutamine
Describe the side Chains of Asparagine and Glutamine (2)
They contain an amide group that can act as an electron donor and acceptor and also contain a carbonyl group (C=O) that can participate in hydrogen bonding
Describe the side chains of Serine and Threonine (2)
They have an hydroxyl group capable of forming hydrogen bonds. They can also be phosphorylated by kinases, resulting in protein modifications.
Polar negatively charged Amino Acids (2)
Apartate, Glutamate
3-letter: Asp
Aspartate
1-letter: D
Aspartate
3-letter: Glu
Glutamate
1-letter: E
Glutamate
Describe the side chains of aspartate and glutamate
Contains a carboxyl group and therefore carry a negative charge at pH 7.0
What are the 3 polar, positively charged amino acids?
Lysine, Arginine, Histidine
3-letter: Lys
Lysine
1-Letter: K
Lysine
3-letter: Arg
Arginine
1-letter: R
Arginine
3-letter: His
Histidine
1-letter: H
Histidine
Which amino acid contains a side chain amino group?
Lysine
Which amino acid contains a side chain guanidinium group?
Arginine
Which Amino acids contains an imidazole group?
Histidine
Where do charged amino acids tend to be located?
The exterior of proteins, in contact with water, because they are very hydrophilic and able to make hydrogen bonds with water
Why are charged amino acids important to enzyme function?
They tend to be located in the active, because they are very hydrophilic and their ability to form hydrogen bonds and ionic interactions with oppositely charged molecules (like other amino acids and metal ions)