A protein with only a single polypeptide chain lacks what structure
Quaternary
What intermolecular force(s) determine the structure of the alpha helix?
Hydrogen bonding
Point out phi/psi angles in a polypeptide
Why does the treatment of some proteins with dithiothreitol change the 3D structure
- DTI reduces disulfide bonds 2. Disulfide bonds are a factor in determining 3D structure 3. They bind different parts of the primary chain together
What is the role of dicyclohexylcarbodimide (DCC) in solid-phase peptide synthesis?
Activation of carboxyl
What is the role of fluorenylmethoxycarbonyl chloride (Fmoc-Cl) in solid-phase synthesis?
* Protection of the amino group * Moc sounds like block, from there think “block and protection”
What does phenyl isothiocyanate (Edman’s reagent) do?
React with the N-terminal amino acid
PAGE of proteins often has sodium dodecyl sulfate added, why?
- SDS denatures the protein and the charges of the SDS swamp the charge on the protein 2. The amount of SDS that binds is proportional to the size of the protein so the net result is electrophoresis separates based on the size of the protein
In peptide synthesis, why is it necessary to add a reagent to activate the carboxyl?
Carboxyl is present as the carboxylate ion, which is a very poor electrophile
What does iodoacetamide do?
React with cysteine side chains
