Flashcards in 9 Protein Folding Deck (24):
what is the general process by which insulin is prepared?
what is the difference between preproinsuin, proinsulin, and insulin? and where is each found?
-prepro has a signal sequence, an A and B chain, and a C peptide. found inside the cell in a reduced form
-pro insulin is created by cleaving the signal sequence from preproinsulin. Found in the ER in an exidized state
-insulin is made by cleaving the C peptide from proinsulin
is preproinsulin oxidized or reduced?
is proinsulin oxidized or reduced?
is insulin oxidized or reduced?
when oxidation occurs, and preproinsulin is turned into proinsulin, what does this allow to happen?
the formation of disulfide bonds between the A and B chains, allowing for much greater stability
the cytoplasm of the cell is usually an oxidizing or reducing environment?
reducing (this is why preproinsulin is reduced and disulfide bonds are not present (Sulfurs bound to hydrogen)
proteins fold to maxmize what>
-weak, noncovalent forces
bone skin and tendon are made up of what type of collagen?
Collagen type 1
reticulin fibers are made up of what type of collagen?
collagen type 3
what are the two standard repeat sequences found in collagen?
other than proline, what else is hydroxylated in collagen?
what does improper hydroxylation of collagen cause and what causes this?
-scurvy (lack of hydroxylation)
-vitamin C deficiency
what end of collagen begins to fold first? the formation of what begins this process?
-c terminus (in most proteins it is the N, which is synthesized first)
-disulfide bonds, intra and inter chain
what causes the elongated helical structure found in collagen?
steric hinderance between prolinesq
what allows collagen chains to pack so tightly together?
so many glycine residues
the conversion of procollagen to tropocollagen takes place where?
what do tropocollagen spontaneously assemble into and how does this happen?
-has a sticky end that attaches to the next collagen
what causes osteogenesis imperfecta?
-a glycine in the collagen triple helix region being mutated to a cystein
why is osteogenesis a dominant mutation?
-because it is a protein with multiple subunits
-all chains have to be correct for the protein to function
explain the mechanism of callagen cross linking
the enzyme lysyl oxidase crosslinks lysine or hydroxylysine to produce allysine
what is the cause of ehlers-danlos syndrome?
caused by either a mutation in a collagen processing gene (heterozygosity ok - recessive) or in the collagen gene itself (heterozygosity not ok - dominant)
mad cow, srapie, creutzfield jabos, and kuru are all forms of what?