Proteins I

Question	Answer
What are proteins?	Linear sequences of amino acids folded to form an elaborate functional product
What configurations of amino acids exist?	L-amino acids are main configurations of aa in proteins D-amino acids exist but not in DNA encoded proteins
What do Gly, Ala, Ser, Cys and His represent?	Gly=H Ala=CH3 Ser=CH2OH Cyst=CH2SH His= big fucker
Draw a diagram showing the bonding in a dipeptide	Partial double bond characteristic between C=O and N of peptide bond, can't rotate Rotation dictated by the sigma bounds between c-CO and c-NH
Draw a polypeptide diagram, what does n represent?	Number of amino acid residues
In a single amino acid, which atom is good for what type of H-bond formation?	O= good H-bond acceptor N:= good H-bond donor
Define secondary structure	Local 3 dimensional shape of a polypeptide sequence as a result of electrostatic interactions between neighbouring residues
Describe the features of an a-helix	R-handed helix 3.6 residues per turn good H-bonding Rigid laterally Stretch longitudinally Side-chains point out from a-helix 100' to preceeding one, more available for interactions
Which amino acids are helix formers?	Glutamate, Glutamine, Ala, His
Which amino acid is a helix destabiliser?	Tyr
Which amino acid is a helix breaker?	Proline
How does it do this?	Proline residue binds with the N of the amino group on Calpha. Therefore Calpha-N bond can't rotate as a result of the protein's cyclical shape.

Resource summary

	Created by J yadonknow over 6 years ago