Molecular Weight Determination and Molecular Weight Distribution of Peptides or Proteins

Our comprehensive service and detailed reports will provide you with the number average molecular weight (Mn), weight average molecular weight (Mw), z-average molecular weights (Mz) and Polydispersity (Mw/Mn) on both single and multi-component polymer samples.

Molecular weight determination of peptides or proteins

For the determination of molecular weights in 2-D electrophoresis gels two different procedures are used.

1. Co-running molecular weight standard proteins.

   Molecular weight marker proteins can be applied as a separate track to the 2-D gel. The molecular weights of the proteins in the 2-D map are then interpolated with the molecular weight curve obtained from the positions of the marker proteins. The problem with this method is its limited accuracy. The markers have to be applied at the lateral sides of the gels. Often the space is very limited and the bands are curved because of the edge effects in SDS PAGE.

2. Interpolation between identified sample proteins with known Mr values.

   Prominent spots showing up in each 2-D map of a sample type can be analyzed for identification and amino acid sequence information. The theoretical Mr values can then be used as key stones for interpolating the Mr values of the other proteins. This method is much more exact than the method described above.

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