Chromogenic Groups

Measure the absorbance of the biotinylated protein solution at 354 nm. Use the molar extinction coefficient for the chromogenic group (e = 29,000 M-1cm-1) to determine the concentration of biotin present. To determine the molar ratio of biotin-to-protein, divide the molar concentration of biotin by the molar concentration of protein present (which may be determined by using the Coomassie assay or the BCA assay methods). 

Versatility - it must be possible to attach the reactive system to a variety of dye chromogenic groupings in manufacture. 

Selecting a sulphonated dye molecule containing an amino group as the nucleophile leads directly to a dichlorotriazine dye. In certain cases a suitable intermediate may be condensed with cyanuric chloride and then the chromogenic grouping is synthesised from this reaction product. Both of these routes are illustrated in a simple way for Cl Reactive Red 1 (7.1) in Scheme 7.7. In these dyes the electronic effects responsible for the lability of the chloro substituents are muted by feedback of electrons from the electron-donating imino bridging... 

Sensing. Crown compounds modified by responsible chromogenic groups (chromoionophores) proved valuable tools for measuring metal ions and even enantiomeric guest concentrations in solution. Ion selective electrodes based on crown compounds and podands as the sensitive component have broad analytical applications from industrial wastewater control to clinical bedside monitoring of blond. 

The primary mechanism of chiral recognition in CE in aqueous conditions seems to be inclusion complexation [464] as discussed above for CD-based CSPs under reversed-phase conditions. Moreover, one of the main advantages of CDs and CD-derived chiral selectors is that they do not carry chromogenic groups, thus being quasi-UV transparent. Therefore, there is no interference regarding detection sensitivity. 

Blue ultramarine (with the chromogenic group 83, herein generally represented as Sx) is formed by slow (up to 20 days ) oxidation of the sulfur in the cavities and channels in the zeolite cage ... 

Macrocycles (crown ethers, cryptands) with chromogenic groups combine the natural selectivity of macrocycles with the possibility of direct spectrophotometric determination of some metals (e.g., K, Ca) in an organic phase after extraction [127-129]. 4-Picrylamlnobenzo-15-crown-5 crown ether (formula 4.41) is applied in the extraction and spectrophotometric determination of potassium. The determinations are based on extractable ion-associates of metals (e.g., Li, Na, K, Pb) with crown ethers and xanthene or sulphophthalein dyes [130]. 

Another approach for aligning CPs involves the use of twining polymers (twimers), which can act as helical hosts that effectively twine around a single CP [16]. It was envisaged that these hosts would integrate chromogenic groups... 

The so-called ionophoreSy which are known under the name neutral carriers if used in ISEs, became meaningful also for optodes. lonophores which carry a chromogenic group are called chromoionophores. However, this term is sometimes used for the combination of ion-exchanging ligand and lipohilic colour indicator. 

Azocasein Method Azocasein is a modified protein bearing a chromogenic group which is released in solution upon digestion. At the end of the reaction, carried out under... 

DLU Method (Lipomax CXT) This method is based on the lipase-catalyzed hydrolysis of l,2-0-dilauryl-rac-glycero-3-glutaric acid resorufin ester at pH 6.8 and 37°C (99°F). A chromogenic group is released. The lipase concentration is proportional to the color intensity, which is monitored by a spectrophotometer. 

Thus, the actinomycins represent a special group of peptides, in which the chromogenic grouping is linked, probably by a peptidic bond (94) with the part of the molecule which may be truly called the peptide. 

It consists of a chromogenic group which bears two identical, cyclic pentapeptide components. Several actinomycins are known they differ from each other in their peptide components. As is often the case with physiologically active peptides, uncommon amino acids e.g. sarcosine, are found as structural components. The occurrence of uncommon components and their cyclization to a ring structure protect the physiologically... 

C. Chou and A. Goldstein, Chromogenic groupings in the Lowry protein determination, Biochem. J. 75 109 (1960). 

They react with Cu(7), Ag(7), Hg(7), II) and the noble metals. When R = H, reaction occurs with loss of H , to give polymeric, insoluble complexes, with bonding to S and N. Incorporation of a chromogenic group at R R gives highly coloured colloidal complexes. When R is an alkyl or aryl group, and... 

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