Bio-Rad Model 491 Prep Cell and Mini Prep Cell - Manual (Page 23)

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4.2 Optimization Procedures
A. Simplified Optimization Procedure
When the difference in the molecular weights of the protein of interest and its near est contaminant is 10% or
greater, select the monomer con centra tion (optimum %T) which corresponds to the size of the protein of interest
from the plot below. In most cases the %T so ob tained will provide adequate resolution for the purified protein.
For gel length and gel tube size determination refer to Sections 4.3 and 4.4.
Fig. 10. Model 491 prep cell SDS-PAGE gel optimization curve. In cases where the difference in molecular weight between the
protein of interest and its nearest con taminant is 10% or greater, the appropriate acrylamide concentration to purify the protein of
interest from it nearest contaminant can be determined using this standard curve.
B. Detailed Optimization Procedure
For samples where the molecular weight of the molecule of interest differs from its nearest contaminant by less
than 10%, we recommend the following procedure. Preliminary optimization is done using mini-slab gels, thus
elim inating lengthy and wasteful trial runs on the Model 491 prep cell.
The detailed optimization procedure involves running a series of analyt ical mini-gels covering a range of %T (in
1–2%T increments). Table 1 gives recom mended ranges of monomer concentrations for various protein molecular
weights. Use Figure 10 to obtain a midpoint for the range of gels to cast.
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Molecular weight of the protein of interest (kD)
Optimum %T