Oligo column

Koizumi, K., Okada, Y., and Fukuda, M., High-performance liquid chromatography of mono- and oligo-saccharides on a graphitized carbon column, Carb. Res., 215, 67, 1991. 

Figure 4.11 Relative abundance for D L -stereoisomer groups of the oligo-tryptophan n-mers (n = 7 and 10, respectively), obtained after two racemic NCA-Trp feedings (a) in the absence (n = 7) and (b) in the presence of POPC liposomes (n = 10). The relative abundances of the stereoisomer subgroups (dark-gray columns) are mean values of three measurements. Standard deviations are given as error bars. The white columns correspond to the theoretical distribution, assuming a statistical oligomerization. (From Blocher et al., 2001.)...

In addition to genomic libraries, cDNA libraries can be prepared from mixed mRNAs. The total RNA of cells is isolated and passed through an affinity column containing oligo(dT) chains. These bind to the 3 -poly(A) tails of the mRNAs, allowing them to be isolated. The mixed mRNAs can then be cloned using a poly(AT)-tailed plasmid vehicle and a reverse transcriptase.183 184... 

Potential packing materials for nucleic acid chromatography have hydrophobic and weakly cationic sites. Figure 22 shows the logarithmic retention factors of oligo-adenylyl phosphates on an ion-exchange column (100x4.6 mm) with ethylene di-... 

A column (250 x 4.6 mm) packed with a reversed-phase C 18 support, coated with trioctylmethyl ammoniumchloride, separated oligo-uridylic acids and discriminated between (Up)89 and (Up)q0, (Fig. 23)83). In such high a region of molar mass, the separation of components differing in only one monomeric unit is remarkable in polymer chromatography in general. 

Phenyl-oligo(ethylene glycol) homologs were separated into individuals on a C 8 column (250x4.6 mm d0 = 6 nm dP = 7 pm) with a water/acetonitrile gradient (from 20 to approximately 33 % B in 30 min) at 2.0 ml/min flow rate87) (Fig. 24). 

Fig. 24. Reversed-phase chromatography of oligomers. Gradient elution of phenyl-oligo(ethylene glycol) homologs on a RP 8 column (250 x 4.6 mm d0 = 6 nm dP = 7 pm). Gradient water/acetonitrile program as indicated 25 °C flow rate 2 ml/min UV detection at 254 nm. (From Ref. S7> with permission)...

Remove excess fluorophore from the labeled oligo using gel filtration on a column of Sephadex G-25, dialysis, or a Centricon centrifugal concentrator. 

For all functional analyses, it is necessary to purify mRNA from the other types of RNA. mRNA constitutes only a small fraction (a few percent) of the total RNA. For separation of mRNA from the rest of RNA, advantage is taken of the fact that most mRNA species have a long poly-A+ tail at their 3 end (2-3). Oligo(dT) or poly-U affinity matrix is used to bind poly A+-containing mRNA that can then be eluted from the column. Several such methods exist with variations in the type of oligo(dT) used or the matrix to which it is attached. 

The Carbowax column is very sensitive to oxidation when the stationary phase is exposed to traces of water or air especially at temperatures above about 160°C. A new type of cross-linking has been reported to impart resistance to oxidative degradation of the stationary phase [5-7]. Two other phases which show promise are an oligo-(ethylene oxide)-substituted polysiloxane (glyme) and an 18-crown-6-substituted polysilox-ane [8]. The glyme column offers a polar phase with good operational conditions to a low of a least 20°C with the same selectivity of Carbowax. The crown polysiloxane selectivity is based on the interaction of the solute molecule with the cavity of the crown ether. 

Figure 2.15 shows chromatograms of octylphenoxy oligo(ethylene glycol)s which are nonionic surfactants that contain the number of ethylene oxide (EO) units indicated on the peaks in Figure 2.15.56 Two columns of differing hydrophobicity were compared, and the octadecylsilane (ODS) column was found to be the more hydrophobic.

Figure 2.15 Chromatograms of octylphenoxy oligo(ethylene glycol)s on an Asahipak GS-310 column (500 x 7.6 mm I.D.) using water/acetonitrile (60 40) as the eluent and on a 5-Hm Unisil Pack ODS column using water/acetonitrile (45 55) as the eluent. Other conditions detection, UV absorbance at 280 nm flow rate, 1 ml/min temperature, 30°C. (Reprinted from Ref. 56 with permission.)...

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