Protein Structure Flashcards
primary structure of protein
amino acid sequences
dipeptide bond
two amino acids connect via condensation
NH3 bonds to COOH, becomes C=O bonded to NH
4 character of peptide bond
partial double bond character
rigid & planar
trans configuration
uncharged yet polar
secondary structure
local fold adjacent to 3D
four types of secondary structures
alpha helices, beta sheet, beta turn, beta loop
main forces creates secondary structure
H bond
what bonding used to maintain alpha helix?
intrachain hydrogen bond
alpha nitrogen & 4th distinct amino acid
how many residue per turn in alpha helix?
3.6 (basically 4)
what AA disrupt aplha helices?
proline & glycine
What type of AA disrupt alpha helices?
charged and bulky R groups
why does proline disrupt alpha helices?
too rigid
why does glycine disrupt alpha helices?
too flexible (all H bonds)
Beta sheets stabilize against each other using?
H bonding
what beta sheet type is twisted into fibrils & result in Alzheimer & Huntington?
Amyloid protein (ABeta)
What beta sheets does protein aggregation happen in for Huntington?
poly glutamine, beta strands, huntingtin protein
Prions cause mad cow disease by inducing formation of what?
amyloid fold (aggregate tight pack B sheet)
Also Creutzfeldt-Jakob Disease
Porin
transmembrane protein in outer membrane of gram negative bactria that act as channel
beta turn
secondary protein structure revers direction of polypeptide chain
What type of amino acids are use in beta turns?
charged, typically proline & glycine as disruptive
how many AA in beta turn?
four
stabilisation forces for beta turns
H bonds and electrostatic interactionsw
where are H bonds in Bturns?
1st and 4th AA
2 classes of tertiary structure
globular & fibrous
examples globular protein
enzyme, transport
main example fibrous protein
collagen, elastin, keratin
forces create tertiary
H bond, disulfide bond, hydrophobic interaction, electrostatic interaction
what is protein denaturation
loss of original tertiary structure
True/False: most proteins can revert to their original tertiary structure after dénaturation?
False: only ribonuclease can refold on its own- all others are permanently altered
quarternary structure?
association of multimeric proteins
forces of quarternnary structure
H bonds, hydrophobic interactions, electrostatic interactions
Sickle cell disease changes to AA
change glutamine reside to caline, causing more fibrous hemoglobin folding so can’t hold oxygen
