Fundamentals of Liquid Scintillation Counting ARTICLES
The mobility (Rf) of a molecule in gel electrophoresis is determined by its free solution mobility, Y0 (= mobility in a gel of zero %) and the sieving action of the gel matrix. In denaturing…
Gradient gels are cast with a higher concentration of acrylamide at the bottom than the top. Gradient gel applications include the determination of protein molecular weights and the separation of molecules which co-migrate on uniform…
Two categories of buffer systems are available for SDS PAGE: continuous and discontinuous. Continuous systems use the same buffer in both the gel and tank. While continuous gels are easy to prepare and give adequate…
SDS is a powerful detergent, which will solubilize many cells and tissues. This greatly facilitates sample preparation for SDS PAGE because most samples will be completely dissolved by heating to 95°C in loading buffer (detailed…
Agarose electrophoresis of RNA requires the inclusion of denaturing agents in the gel. In the absence of denaturants, RNA assumes compact secondary structures, which distort the relationship between molecular weight and mobility.Urea, used as a…
Electrophoretic analysis of RNA presents unique challenges. RNA is isolated in single-stranded form, without complementary sequences. It must be fully denatured in order to obtain fractionation based on size. However, RNA molecules form complex and…
Standard agarose gels can resolve DNA fragments up to 75 kb. Often, analysis of genomic DNA requires resolution of megabase (mb) fragments. Fragments greater in size than one megabase all run at the same rate…
In many cases, the processing of DNA by enzymes is not impeded by agarose. Such reactions can be run directly in bands excised from low melting point agarose gels. The excised band is melted, mixed…
The most popular alternative to glass powder elution for the complete purification of DNA from agarose is electroelution. Because agarose gels are run in a horizontal apparatus, the gel can be manipulated during a pause…
Restriction endonucleases are enzymes that cleave double-stranded DNA at specific sites, generally 4, 6 or 8 base palindromic sequences. Because, in action, the enzymes are sequence-specific, each piece of DNA has a recognizable pattern (or…