MCAT Protein Isolation + Chromatography Review

Native polyacrylamide gel electrophoresis (Native PAGE)

Sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (SDS-PAGE)

Isoelectric Focusing

Thin-layer + paper chromatography

Nonpolar compounds move up sheet via capillary action

Reverse-phase chromatography

Polar compounds move up sheet via capillary action
Uses stains or UV light

Column chromatography

Uses gravity and either silica or aluminum beads to move solvent + compounds down
Flash column chromatography: w/ gas pressure

Ion-exchange chromatography

Column chromatography w/ beads coated w/ charged substances

Size-exclusion chromatography

Column chromatography w/ pores that slow down TINY compounds

Affinity chromatography

Protein bound in column with high affinity for protein
(coating beads w receptor or antibody)
E.g., histidine tags, antibodies/antigens, enzyme substrate analogues, etc.

Gas chromatography, i.e. vapor phase chromatography

Column chromatography w/ gas as eluent pushing vaporized mixture down
Adsorbent is crushed, injected compounds must be volatile

High-performance liquid chromatography (HPLC)

Column chromatography w/ liquid as eluent and can modify solvent gradient + temperature within column using computer