Nucleic Acids

LLPC in aqueous two-phase systems has been successfully used for DNA fractionation by size, topology and by base sequence, as well as for the fractiona-tion of 'soluble' and ribosomal RNAs (Table 4). Hence, LLPC may provide resolutions unattainable by any other method.

Size DNA fragments, linear relationship for fragments up to about 4000 base pairs

Various RNAs from natural sources, e.g. soluble RNAs from tomato plants Ribosomal RNA up to about 30 S

Base composition Eco RI generated fragments from X DNA

Calf thymus DNA

Topology Fractionation of circular DNAs

LLPC, liquid-liquid partition chromatography.

Fractionation of DNA restriction fragments by size can be performed with DNA fragments up to at least 4000 base pairs (Table 4). Mainly two-phase systems formed by PEG 8000/dextran 500 have so far been applied (Table 1). The separation can be greatly improved by applying a salt-exchange gradient. Side effects, possibly caused by slightly hydrophobic properties of the supports, may strongly influence the fractionation of DNA. Although the influence of the supports on DNA may be obvious, as in the case of proteins (see below), the general applicability of the matrices is not invalidated as the interactions may be exploited as an additional parameter for separation.

DNA may be fractionated according to base composition or sequence using PEG-bound AT- or GC-specific DNA ligands consisting of basic dyes (Table 4). In this way, these ligands will prefer the PEG-rich mobile phase and are subsequently able to shift the partitioning of matching DNA towards this phase. As in the case of DNA, RNA may also be fractionated by LLPC in aqueous two-phase systems due to differences in size. Also large (ribosomal) RNA ranging up to 30 S can be fractionated by LLPC. The high solubility of RNAs in the PEG/dextran systems is also advantageous.

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

Get My Free Ebook


Post a comment