Bleaching procedure modifications

The procedure in the polygon in Figure 1 is the Hagerman Butler assay for tannin. The only modification is that we retain the supernatant after centrifugation of the precipitation reaction mixture and bleach the monomeric anthocyanins with bisulfite. The residual absorbance represents pigments that do not precipitate with protein and do not bleach in the presence of bisulfite. We have designated this material small polymeric pigment solely to denote these two characteristics. The LPP removed from the sample by protein precipitation... 

The constant C is a function of the sensitizer triplet yield and the subsequent efficiency with which reaction with oxygen yields 02(1Ag). The procedure only yields fcd/fcq, the so-called /J-value, from slope to intercept ratios in the presence and absence of quencher, Q. As mentioned, a knowledge of fcd from time-resolved data gives fcq. Modifications of this approach involve the use of DPBF [42] or rubrene [43] as monitors, the decay of these molecules being followed by loss of fluorescence intensity and bleaching respectively. 

The bilin chromophores of either the a- or the B-subunit of phycocyanin, or both, were (photo)chemically modified and recombined with the respective missing subunits. The modifications consisted of photo-bleaching, or reduction of the verdin- to rubin-type chromophore(s). It was not possible to obtain trimeric phycocyanin (aB) from such modified preparations by the recombination procedures used, irrespective of the modification being done with PC in toto, or with isolated subunits which were then recombined with the complementary subunit containing unmodified chromophores. All products are at most dimeric aggregates (Fig. 1). Also, addition of a functionally active linker peptide (22 kDa), which... 

The halogens and their oxyacids probably are the most important oxidants used in the carbohydrate field. They are widely used as bleaching agents, but the mechanism of this action remains to be clarified. As reagents for preparatory purposes (particularly for aldonic acids and lactones) and for analytical procedures, they are very important. Periodic acid, discussed in a later section, has an important application for the elucidation of structures of carbohydrates. A number of valuable commercial products are made by treatment of polysaccharides with halogens, particularly chlorine or hypochlorous acid, but the nature of these actions, such as the modification of starch, has not been clarified. 

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