Dye Ligands

Figure 1 Structures of the parent textile dye Cibacron Blue 3GA (CB3GA), (A) the three blue (B)-(D) and one yellow (E) biomimetic dyes, and the blue dye (F) for selective LDH precipitation.

beginning of a new era in affinity bioseparation. This approach is based on a generation of the so-called biomimetic dyes. By employing molecular modelling techniques, it is possible to redesign the parent dye (e.g. CB3GA) or design de novo a new dye in such a way that the resulting biomimetic dye mimics naturally occurring biological ligands, thus displaying increased selectivity for the targeted enzyme. Figure 1 shows the structures of the parent dye CB3GA (A) and four biomimetic dyes (B-E). For the case of the NAD + -dependent enzyme alcohol dehydrogenase (ADH), having used molecular modelling to compare the conformations that NAD+ and CB3GA adopt during binding to the enzyme, it was possible to propose the biomimetic structure of Figure 1(B) that exhibits increased affinity for ADH as compared to CB3GA. Recently a family of anthraquinone biomimetic dyes has been designed specifically for (keto)carboxyl-group-recognizing enzymes. Each member of this dye family is composed of two enzyme-recognition moieties (e.g. Figure 1C). The terminal biomimetic moiety bears a (keto)car-boxyl structure linked to the triazine ring, thus mimicking substrates of the targeted enzyme, e.g. l-malate dehydrogenase (MDH). The chromophore anthraquinone moiety remains unchanged and the same as that of the parent dye (Figure 1A), recognizing the nucleotide-binding site of MDH. Members of this dye family show increased affinity for the targeted enzymes and have been designed for other enzymes as well, e.g. l-lactate dehydrogenase (LDH). In the case of the orthophosphate ester hydrolase alkaline phosphatase, a biomimetic dye was designed by substituting the terminal 2-aminobenzene sulfonate of CB3GA for a 4-aminobenzene phosphonate ring (Figure 1D). The corresponding dye adsorbent offers an impressive purification of calf intestinal alkaline phosphatase of over 300-fold in a single chromatography step. The biomimetic structure of Figure 1(E) is a benzamidino-cationic yellow dye designed for a different application. The cationic dye bears a guanidino group, the same as the potent trypsin inhibitor benzamidine. When the dye is immobilized, it is able to separate the two main proteolytic constituents of crude pancreatic extract, trypsin and chymotryp-sin, since only the former enzyme is adsorbed. The use of biomimetic dyes is expected to increase and help towards simplifying enzyme purification problems.

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.

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