BMP: Amino Acids Flashcards
What are proteins?
Linear polymrs of amino acids
- What is the basic structure of an AA?
- What is the exception?
- A carboxylic acid group, amino group and side chain attached to the a-carbon
- Proline
How does proline differ?
The side chain and a-carbon form a ring structure so proline contains an imino group rather than an amino group
- What is physiological pH?
- What happens to the AA at physiological pH?
- 7.4
- The carboxylic acid and amino group are dissociated. The carboxylate ion is formed (-COO-) and the amino ion (-NH3+)
What type of bonding occurs in amino acids? What does this mean?
Peptide bond so no chemical reaction bar h-boinding can occur
- /What do the side chains of AA dictate?
- What are the classes of AA?
- The role an AA plays in the protein
- Non-polar, uncharged, acdic, basic
What are the features of an non-polar side chain?
each has an aromatic, aliphatic or non-polar side chain. Don’t give off protons or paricipate in h-bonding or ionic bonding. Thought of as oily/ lipid-like and promoting hydrophobic interactions
What are examples of AA with non-polar side chains
- Leucine
- Isoleucine
- methionine
- valine
- proline
- glycine
- phenyalalnine
- tyrosine
- tryptophan
- Alanine
Describe the location of these AA with non-polar side chains in proteins
In an aqueous enviroment they cluster in the interior of the proteins due to the hydrophobicity of the R-groups. This fills the interior of the protein and creates the protein 3D shape
What are the properties of uncharged side chains?
NEt charge of 0 at neutral pH
What are examples of AA with uncharged side chains?
- Serine, theronine, tyrosine contain a hydroxyl group which can participate in H-bond formation
- Glutamine and asparagine contain a carbonyl group and amide group which can participate in H bonding
- Cysteine contains a sulphydryl group (-SH). When 2 sulphydryl groups of 2 cysteine AA become oxidised it forms a dimer, cystine, which conatinas a convalent vrosslinked disuphode bond
What do the side chains of uncharged AA do?
the polar hydroxyl group of serine, theronine and sometimes tyrosine serves as a poiny of attachment for molecules e.g. phosphate group
The amide group of asparagine and hydrocyl group of serine and theronine serves as a site of attachment for oligosaccharides in glycoproteins
What are examples of acidic side chains and there properties?
Asparatic acid and glutamic acid. At neutral pH the side chain completely ionised to form carbocylate group (COO-)
Also known as glutamate and aspartate
Examples and properteis of basic side chains
- These are proton acceptors.
- At physiologic pH the side chains of lysine and arginine are fully ionised and positively charged.
- Histidine is weakly basic and the free amino group is largely uncharged at physiologic pH.
- When histidine is incorporated into a protein, its side chain can be either positively charged or neutral, depending on the ionic environment provided by the polypeptide chains of the protein.
Naming system:
See notes
