Bases, chromatography

Various chromatographic techniques may be utilized to purify urokinase further. Commonly employed methods include anion-exchange (DEAE-based) chromatography, gel filtration on Sephadex G-100 and chromatography on hydroxyapatite columns. Urokinase is a relatively stable molecule. It remains active subsequent to incubation at 60 °C for several hours, or brief incubation at pHs as low as 1.0 or as high as 10.0. 

The most common types of MS/MS instruments available to researchers in food chemistry include triple quadrupole mass spectrometers and ion traps. Less common but commercially produced tandem mass spectrometers include magnetic sector instruments, Fourier transform ion cyclotron resonance (FTICR) mass spectrometers, and quadrupole time-of-flight (QTOF) hybrid instruments (Table A.3A.1). Beginning in 2001, TOF-TOF tandem mass spectrometers became available from instrument manufacturers. These instruments have the potential to deliver high-resolution tandem mass spectra with high speed and should be compatible with the chip-based chromatography systems now under development. 

Haginaka J (2008) Monodispersed, molecularly imprinted polymers as affinity-based chromatography media. J Chromatogr B Anal Technol Biomed Life Sci 866(l-2) 3-13... 

Suppressor-based chromatography A chromatographic technique involving a column or a membrane located between the analytical column and a conductivity detector its purpose is to convert ions of the eluting solvent into nonconducting species while passing ions of the sample. 

Many of the techniques used to enrich PTMs at the protein level are applicable at the peptide level. A popular method for enrichment of phosphopeptides is to use an immobilized metal affinity column. The molecular basis for the enrichment is the phosphate affinity to transition metal ions, such as copper, nickel, cobalt, iron, aluminum, gallium, and zinc (142). A comprehensive source for phosphopeptide enrichment strategies can be found in a recent review (143). Lectin-based chromatography is used to enrich for glycopep-tides (144). Lectins are proteins that have an affinity for carbohydrates. With multiple available enrichment options, choosing the right one for the experiment is important. For determining which proteins have a certain PTM, protein-level enrichment can be performed. However, if a type of PTM is of... 

Warner, T.N. Nochumson, S. A work in process membrane-based chromatography is paving the way for throughput biopharmaceutical processing. Mod. Drug Discov. 2003, 6, 45 9. 

Supercritical fluid chromatography uses most of the same or slightly modified hardware. The greatest difference is that most of the normal liquid used as the mobile phase in HPLC is replaced with a liquefied gas, like carbon dioxide. Fluids other than carbon dioxide can be used, but for all practical purposes, SFC means C02-based chromatography. 

Carbon dioxide based chromatography, with a mobile phase of carbon dioxide and mixtures of carbon dioxide plus modifiers ranging from suboritlcal to supercritical states, is a young but exciting area for study. Investigators can choose from a wide range of possible experiments from fundamental physicochemical studies to semi-empirical frameworks to analytical methods-development for complex mixture separation. It is hoped that the preliminary results described in this paper will be useful to others in this area and will stimulate future work that will result in routine optimization schemes for SFC separations like those presently under development for LC separations. 

Figure 6.29 (a) molecular model of the chiral tweezers 6.53, (b) the chiral guest that forms part of the 7T-acidic stationary phase, a (3/ ,45 ) Whelk-0 1 silica-based chromatography column. 

Barnea E, Sorkin R, Ziv T, et al. (2005). Evaluation of prefractionation methods as a preparatory step for multidimensional based chromatography of serum proteins. Proteom. 5 3367-3375. 

Tabie 1 A Comparison Between Immunoaffinity Chromatography and MIP-Based Chromatography... 

Characteristic features Immunoaffinity chromatography (including antiserum production) MIP-based chromatography (including polymer preparation)... 

Ebara, M. Hoffman, J. M. Hoffman, A. S. Stayton, P. S. Switchable surface traps for injectable bead-based chromatography in PDMS microlluidic channels. Lab Chip 2006, 6, 843-848. 

---