Lecture 4- Protein Strucutre Flashcards
What is a zwitterion
It is the ionised form of an amino acid. The form found in the body nh3+ and coo-
What is an amino acid residue?
Part of amino acid left after it has been joined by a peptide bond to form a protein.
If pka is 9 but PH is 7.4 will amino acid be protonated or deprotonated
Protonated as ph is Lowe will be more H+ and so it will take a proton.
What way are peptide bonds?
Planer and rigid due to partial double bond characteristics
How do you tell if a peptide is trans or cis?
Trans if R groups opposit cis if they’re on the same side.
What is the PI or isoelectric point of a protein?
It is the pH at which there is no net charge on the protein. For acidic proteins it will be less than 7 etc. It can be found by averaging the pka’s of the amino acid residues.
What is pka of an amino acid?
Measure of the likelihood of the amino acid to be ionised.
What is a conjugated protein?
One that has a covalently linked chemical compound in addition to the amino acids. Eg the heme or iron porphyrin ring in haemoglobin
What holds primary structure together?
Covalent bonds
What hold secondary structure together?
Hydrogen bonds
What is tertiary structure?
Spatial arrangement of amino acids far apart in the protein sequence
What is secondary structure
The linear amino acid sequence and how they interact with each other.
What is interesting about secreted proteins?
They tend to have more covalent bonds to hold them together in an unstable environment.
What type of bonding do you get in tertiary protein structure?
Generally non-covalent but can be anything
A lot of disulphides bonds as with quarternarmy structure
Also get hydrogen bonds, van der walls, hydrophobic interactions and ionic bonds
Do you know polarities etc of amino acids? Be able to recognise them?
Yes or no
