Biotinylated standards provide accurate molecular weight determinations for blotting applications. Because biotinylation does not significantly increase the molecular weight of these proteins, they provide accurate molecular weight determinations for blotting systems.

The standards are detected by binding avidin-HRP or avidin-AP to the biotinylated proteins, followed by the appropriate color development reagent. The biotinylated standards are available in a high molecular weight range (45,000�200,000), low range (14,400�97,400), and broad range (6,500�200,000). See Electrophoresis Standards for a comparative analysis of Bio-Rad's standards for SDS-PAGE, IEF, and blotting.