Polypeptide molecular weight detection

with the rapid development of molecular biology and biotechnology, with high biological activity of peptide compounds separation, purification, and analysis has been particularly prominent. Many isolation, purification, and analysis techniques are based on size of molecular weight as a means, we use several technologies are as follows:

gel filtration measuring relative molecular weight of

this technique, gel filtration chromatography, also known as molecular exclusion chromatography or gel permeation. Using gel filtration protein and peptide mixtures can be separated by molecular weight size. When protein and peptide mixtures of different size through gel chromatography column, due to the different size of the path are separated different molecules were cleared out, small molecules to be cleared out.

this method is simple and does not require sophisticated instruments can accurately measure the relative molecular weight of protein polypeptide. In addition, using this technology Mr (molecular weight) also has an advantage, that is, the object to be tested can be impure.

which cross-linked dextran is generally used as the base material, the trade name for Sephadex. SephadexG-25 as needed (the fractionation range of Mr 5000), SephadexG-75 (Mr 3000~80000 range), SephadexG-100 (Mr 4000~150000 range). The experiment, based on protein molecular weight on the value of the standard as ordinate and Elution volume of standard curve for the abscissa. According to the elution volume of product to be tested from the standard curve found on Mr.

SDS polyacrylamide gel electrophoresis measuring relative molecular weight

in polyacrylamide gel electrophoresis system adding anionic detergent 12 alkyl sulfonate (SDS) and a small amount of mercaptoethanol, electrophoretic mobility of the protein and peptide mixtures will mainly depend on their relative molecular weight and has nothing to do with the charge and shape.

at present, the small molecular peptides by SDS polyacrylamide gel electrophoresis, choosing the right system and the right kind of separation gel, condense and even the gap glue of concentration and the degree of cross-linking is a research topic. In addition, you should select appropriate range protein molecular weight standards, makes the measure of molecular weight will fall within this range.

when measured, the logarithm value of Mr in all standard proteins as ordinate and μr (relative mobility) standard curve for the abscissa. According to measure μ on r from the standard curve to identify their Mr.

high performance gel-exclusion chromatography (HPSEC) technology measuring relative molecular weight

HPSEC is based on molecular sieve principle and chromatography method for high-speed movement of the mobile phase, the rapid, sensitive, and effective, for the treatment of experimental results the same as gel filtration.

stationary phase pore size and speed directly affects the mobile phase separation. Fixed Pw and Sw two kinds of raw materials, but under normal circumstances, first consider Sw type. Main specifications are TSK-2000Sw (suitable for 5000~100000 peptides), TSK-4000Sw (for 50000~1000000) and so on. Mobile phase generally buffer (often used phosphoric acid or acetic acid buffer), also containing organic solvents (methanol or acetonitrile) and denaturing agent (urea, Guanidine, SDS).

these peptides are briefly introduced several techniques for determination of molecular weight. With the development of science and technology, there will be many newer technologies are emerging, and therefore research in this field has broad prospects.