Studied by 2 peopleAmino Acids
Why are amino acids called such
Called like such because:
Have and amino group
Have an acid( carboxyl group)
How do each amino acid differ?
The difference between each amino acid is with the R or chain
What are the structures common to all amino acids?
hydrogen
amino group
carboxyl group
central alpha carbon
What determines the different properties in amino acids?
The properties of their side chains
List the different categories based on grouping AAs by side chain properties
Non-polar aliphatic
Aromatic
Polar, uncharged
Polar, positively charged
Polar negatively charged
Main components of non-polar aliphatic AA/ where it’s found
Mainly hydrocarbon side chains
-no charge
-no h-bond capacity (hydrophobic)
Found in the core of a protein
_____ is often found at polypeptide turns due to its unique ______ formation.
Proline, cyclic
________ is the smallest amino acid and is usually found after ____ for a tight turn.
Glycine, proline
Main components of aromatics AA/ where it’s found
Contains a ring within its side chain
Role of phosphorylation in biomolecules?
A mechanism to regulate protein function; usually reversible
Which type of AA can be phosphorylated?
Amino acids with hydroxyl groups
What is Post-Translational Modification?
Protein modification after they have been made
phosphorylation
Explain basics of phosphorylation and enzymes involved
The addition of phosphoryl groups added to AA containing a hydroxyl group
kinase recognizes and adds the phosphoryl groups to OH ends
phosphatase removes the phosphoryl groups from AA
Which AA is the largest?
Tryptophan
Main components of polar uncharged AA/ where it’s found
Contains dipoles ready to h-bond
What are the two AA containing sulfur?
Methionine, Cysteine
What are two examples of post-translational modification?
phosphorylation
disulfide bond formation
How are disulfide bonds formed?
Formed through the oxidation of the sulfhydryl groups of two cysteines that will form a covalent bond
AA needs to be close within the molecule
Can be inter or intramolecular
What is the function of a disulfide bond?
Function to stabilize protein structure
Main components of polar charged AA/ where it’s found
Always carry a +1 charge at physiological pH
h-bond capability
What’s special about histidine?
Can change its protonation state within the body
Some will be of protonated and the rest unprotonated form within the body
Usually serves as a proton donor/ acceptor
When will be the charge of the imidazole group in histidine in its protonation states?
protonated state [A-]: positive charge
unprotonated state[HA]: negative charge
What is histodine’s pKa?
6
What is meant by “protonated” form?
When a functional group has an extra proton/ H+ ion.
Where is the protonated form of a function group found in terms of the pKa?
Under the pKa,
Where is the unprotonated form of a function group found in terms of the pKa?
Over the pKa
Zwitterion
When an AA has opposite charges ( net sum is zero) in both ions
Isoelectric point pI
The pH where the net charge of the molecule is zero
How do you calculate pI?
Taking the average on either sides (pKa points) of where the net charge of the molecule equals zero.
How many pIs are allowed per molecule?
1 pI
Which letters in the alphabet are not attributed to an amino acid code?
JOB
Note
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