lecture_5 - ProteinPurification...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
Protein Purification Before any particular protein can be sequenced and characterized, its is necessary to separate it from all of the other proteins in the cell. This “purification” process involves separating proteins based on their ionic properties , their sizes, their hydrophobicity , and their affinities for certain molecules (ligands). Each successive step is referred to as fractionation . Typically some form of column chromatography is employed, in which the solid phase (stationary phase) contains molecules that in some way exploit the differences among various proteins.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Ion-Exchange Chromatography This procedure is very similar to the procedure that we talked about for separating amino acids based on charge. The picture at the left represents ion- exchange chromatography on a cation exchanger. Notice that the bead is negatively charged, and therefore the rate of mobility of proteins loaded onto the resin is proportional to the degree of negative charge that they bear.
Background image of page 2
Size Exclusion Chromatography In size-exclusion chromatography (gel-filtration chromatography), proteins migrate as a function of their molecular weights. The solid matrix (beads) contains pores of various sizes. The probability of entering the pores of the matrix is inversely proportional to the size of the protein. In fact proteins that are larger than a given size (depending on the resin that is used) are totally excluded from entering the beads. Therefore, larger proteins have a more direct route to the bottom of the column, by simply going around all of the beads rather than entering the beads. Notice in the figure at left that the large molecules elute first.
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 10/18/2008 for the course BIO 120 taught by Professor Ashena during the Spring '06 term at Punjab Engineering College.

Page1 / 11

lecture_5 - ProteinPurification...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online