protein and protein structure Flashcards
shapes of proteins
globular
fibrous
membrane spanning
what is protein conformation
arrangement of the amino acid side chains in 3D space
protein structure
primary - order of aa
secondary - folding of local regions into regular structures
tertiary - folding of secondary elements into 3D shape
quaternary - different protein subunits come together
influences on the shape
chaperones water cysteine bonds (help form disulphide bridges) hydrogen bonds regular structures
secondary protien
alpha helix
beta pleated sheet
beta turn
- can be interspersed with non reg coils/loops
alpha helix
tightly coiled rod
hydrogen bonding
beta pleated sheet
hydrogen bonds between two parts of protein far apart
beta turn
non regular struture
hair pin loop that form with polypeptide structures
4aa
may be found at the end of the beta pleated sheet
tertiary structure
3d allows binding site for ligands act have domains (indépendant regions) maintains appropriate residues on surface
chaperones
specialised proteins forming barrels
assist in folding of polypeptides
removes effect of water and uses ATP to fold protein
quaternary proteins
non covalent bonds to form one protein
homo/hetero
can be dimers, tetramers, oligomers
protein denaturation
conformation lost due to bond disruption, function lost
causes of protein denaturation
pH-affects charge
temperature - thermal energy disrupts bonds
acid, base, high salt - disrupts electrostatic interactions
what are examples of misfolded protiens
prions
cannot be removed by sterilisation
act as a template to induce pathological misfolding
CJD diseases
protein misfolding and disease
aggregation of misfolded proteins can form plaques in brain
tight layers of beta pleated sheets packed together
leads to: Alzheimers, huntigtons, Parkinson’s
