Bio-Rad Criterion™ TBE-Urea Precast Gels - Manual (Page 20)

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Native PAGE
4
4.1 Introduction
In native PAGE, proteins are prepared in nonreducing, nondenaturing sample buffer, which maintains
native structure and mass-to-charge ratios. Separation is also performed in the absence of SDS and
reducing agents. Though native PAGE uses the same moving boundary described for SDS-PAGE
(see Section 3.1), protein mobility depends on a number of factors besides molecular weight, including
the shape and charge of the protein. Protein-protein interactions may be retained during native PAGE,
so some proteins may separate as multisubunit complexes. Consequently, native PAGE is not suitable
for molecular weight determination.
The nonreducing and nondenaturing environment of native PAGE allows protein separation with
retention of biological activity. Because native structure is retained, native PAGE can allow resolution of
proteins with the same molecular weight.
4.2 Criterion ™ Gel Selection Guide for Native PAGE
Table 4.1. Criterion precast gels for SDS-PAGE.
Gel Formulation Gels Description
Laemmli-like Criterion ™ TGX ™ Laemmli-like, extended shelf life gels
Criterion ™ TGX Stain-Free ™ Laemmli-like, extended shelf life gels with trihalo compounds for rapid
fluorescence detection
Tris-HCl (Laemmli) Criterion Tris-HCl Tris-HCl Laemmli gels
Criterion Stain Free ™ Tris-HCl Laemmli gels with trihalo compounds for rapid fluorescence
detection
Tris-acetate Criterion ™ XT Tris-acetate Based on a Tris-acetate buffer system (pH 7.0)
4.2.1 Criterion TGX and Criterion TGX Stain-Free Gels
Criterion TGX (Tris-Glycine eXtended shelf life) gels are Tris-HCl, Laemmli-like gels with a proprietary
modification that extends their shelf life to 12 months and enhances separation characteristics relative to
conventional gel types. The TGX formulation yields Laemmli-like separation patterns with exceptionally
straight lanes and sharp bands and has excellent staining quality and transfer efficiency.
These gels are run using native sample buffer and Tris/glycine running buffer.
Two types of TGX formulations are available:
n
Criterion TGX — Laemmli-like gels with the TGX formulation
n
Criterion TGX Stain-Free — Laemmli-like, extended shelf life gels that include unique trihalo
compounds that allow rapid fluorescent detection of proteins with the Criterion Stain Free
system, eliminating staining and destaining steps for faster results (see Chapter 5 for more
details)