Oligomer biological

SI O Donoghue, M Nilges. Calculation of symmetric oligomer stiaictures from NMR data. In R Krishna, IF Berliner, eds. Modern Techniques m Protein NMR, vol. 17 of Biological Magnetic Resonance. New York Kluwer Academic/Plenum, pp 131-161, 1999. 

Biologically Active Pectin Oligomers in Ripening Tomato Fruits... 

Table II. Carbohydrate compositions (weight percentage) of individual oligomer peaks purified (QAE-Sephadex or HPLC ion-exchange separation, respectively) from mixtures of citrus pectin oligomers or B fruit extracts Compositions shown are for peaks whose biological activity is described in Figure 4. Uronic acid values are based on colorimetric assay. Proportions of neutral sugars were determined by GC and adjusted so that totals equal 100%. In fact, some oligomers (G7 peaks 8, 9 and 10. B extract peak 10) produced small (less than 1 % of the total integrated area), unknown peaks in the GC chromatograms.

To date only homooligogalacturonides from plant pectin have been shown to exhibit the regulatory effects. Meanwhile pectin polysaccharides consist of neutral highly branched blocks, so it was of interest to search for possible biological activity of oligomers released from such structures. 

The separations of some nonionic tensides having biological activity and consisting of ethyleneoxide oligomer mixtures were performed in many different TEC systems (silica and alumina as the stationary phase and single solvent or binary mixtures as the mobile phase). Selectivity was higher on alumina than on the silica layer. Both... 

Aggregation of proteins is a microscopic process of protein molecule association. The aggregates may be dimers or larger oligomers that remain in solution, yet may alfect the observed biological activity. Precipitation refers to the formation of visible proteinaceous particles, which may reduce potency in addition to altering the appearance of a formulation and its performance in various infusion devices. 

Haslam, S.M., Houston, KM., Harnett, W., Reason, A.J., Morris, H.R. and Dell, A. (1999) Structural studies of phosphorylcholine-substituted A-glycans of filarial parasites conservation amongst species and discovery of novel chito-oligomers. Journal of Biological Chemistry 274, 20953-20960. 

Indeed, hydrophilic N- or C-terminal ends and loop domains of these membrane proteins exposed to aqueous phases are able to undergo rapid or intermediate motional fluctuations, respectively, as shown in the 3D pictures of transmembrane (TM) moieties of bacteriorhodopsin (bR) as a typical membrane protein in the purple membrane (PM) of Halobacterium salinarum.176 178 Structural information about protein surfaces, including the interhelical loops and N- and C-terminal ends, is completely missing from X-ray data. It is also conceivable that such pictures should be further modified, when membrane proteins in biologically active states are not always present as oligomers such as dimer or trimer as in 2D or 3D crystals but as monomers in lipid bilayers. 

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