Glucose spectral differences

Biologically important species, including amino acids, have unique spectral features which can be exploited to provide measurement selectivity. In the region of 5000 - 4000 cm , the major absorption contributions come from combinations of vibrational transitions for ahphatic C-H, alkene C-H, amine N-H (ionized or not) and 0-H bonds (8). Such spectral differences have been used to selectively measure structurally different compounds, such as glucose and ammonium ions (9), and glucose and glutamine (10). 

The spectra of the peracetylated P-D-glucose are used as a reference in two ways. Firstly they serve in a comparative way to let you verify your results when studying the effect of different data manipulations and the influence of different processing parameters on the processing of the experimental raw data (FID). Secondly they serve as a reference of various NMR parameters (shifts, coupling constants,. ..) and give you valuable spectral information to help elucidate the unknown structure of the peracetylated oligosaccharide. 

Figure 15-2 Absorption spectra of NAD+ and NADH. Spectra of NADP+ and NADPH are nearly the same as these. The difference in absorbance between oxidized and reduced forms at 340 nm is the basis for what is probably the single most often used spectral measurement in biochemistry. Reduction of NAD+ or NADP+ or oxidation of NADH or NADPH is measured by changes in absorbance at 340 nm in many methods of enzyme assay. If a pyridine nucleotide is not a reactant for the enzyme being studied, a coupled assay is often possible. For example, the rate of enzymatic formation of ATP in a process can be measured by adding to the reaction mixture the following enzymes and substrates hexokinase + glucose + glucose-6-phosphate dehydrogenase + NADP+. As ATP is formed, it phosphorylates glucose via the action of hexokinase. NADP+ then oxidizes the glucose 6-phosphate that is formed with production of NADPH, whose rate of appearance is monitored at 340 nm.

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