Protein Structures 1 Flashcards
Levels of Proteins Structure
Primary Structure, Secondary. Tertiary, Quaternary
Primary Structure
complete set of covalent bonds within a protein
Why can’t a peptide bond form as by definition?
It requires specific activation over overcome energy barrier for reaction and need helps from enzymes to form the bond. It doesn’t happen spontaneously.
Why is a peptide bond planar and rigid?
The peptide C-N bond has a partial double-bond character (estimated at 40%
under typical conditions, partial sharing of two pairs of electrons between O and
N).
resonance
delocalization of bonding electrons over more than one chemical
bond
Is peptide bond normally in trans or cis configurtion?
trans configuration
except proline which makes the aa constrained
what does “complete description of the covalent bond network” mean?
this is talking about the covalent bonds between amino acid at the C-N bond and between side chain atoms
backbone atom pattern
-N-Ca-C-N-Ca-C-N-Ca-C-N-Ca-C-
Ramachandran Plot
graph that helps scientists understand the angles in the backbone of a protein
x-axis (horizontal) shows one type of angle, called ϕ (phi)
y-axis (vertical) shows another type of angle, called ψ (psi)
phi
C - N - C-alpha - C
ϕ
psi
N - C-alpha - C - N
ψ
backbone dependent
phi & psi
backbone independent
omega
Peptide bonds are in WHAT configuration? Why?
trans because trans in not constrained while cis is.
A constrained configuration makes it difficult for the protein to be flexible and move.
disulfide bond
strong covalent bond formed between two sulfur atoms of two cysteine amino acids (and produces a cystine)
It stablizises a protein which makes it rigid and less likely to unfold (like a glue)
Seen in enzymes
