US Patent 7781173 Homogeneous populations of molecules

The invention provides populations of molecules that are prepared as, or treated to become, homogeneous for one or more molecular characteristics. In an aspect, the invention relates to molecular weight standards that may be used to determine the molecular weight or apparent molecular weight of uncharacterized molecules, such as proteins and nucleic acids, as well as in other applications. In one aspect, the molecular weight standards are pre-stained.