protein techniques Flashcards
what happens at the isoelectric pH of a tetrapeptide?
the total net charge is zero
what determines the order of elution in gel filtration chromatography?
the smaller the molecule, the later they elute as they spend more time within the pores.
why do larger molecules elute first?
they are not slowed down by interactions with the stationary phase
during two-dimensional gel electrophoresis what happens after a series of protein bands by isoelectric focusing are generated and current is applied?
proteins with similar isoelectric points become further separated according to their molecular weights.
The relative mobility of different proteins during SDS-polyacrylamide gel electrophoresis is primarily determined by which property of the proteins?
mass
two-dimensional electrophoresis is a combination of what two techniques?
isoelectric focusing and SDS-PAGE
what is isoelectric focusing?
- separates proteins based on their isoelectric point
- proteins migrate in an electric field toward the pH gradient until they reach their isoelectric point, where they stop moving due to no net charge.
what is SDS-PAGE
- separates proteins based on their molecular weight
- SDS denatures the proteins and binds to them in a consistent manner, giving each protein a similar charge-to-mass ratio.
- proteins migrate through a polyacrylamide gel under the influence of an electric field, with smaller proteins moving faster than larger ones.
what is the advantage of adding SDS to gel electrophoresis?
SDS allows proteins to be separated on the basis of approximate mass.
Which of the following techniques is most useful for fractionating a heterogeneous protein mixture by size?
Gel-filtration chromatography
Which type of protein purification relies on the attraction of the protein for a particular chemical group?
affinity chromatography
