{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

lecture_5 - ProteinPurification ,itsisnecessary thecell...

Info icon This 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.
Image of page 1

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

View Full Document Right 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.
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.
Image of page 3

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

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

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern