Resonance units

All proteins, independent on their aminoadd con odtion, aher the refi active index of water by a dmilar amount per unit mass, and thus there is a linear correlation between the surfiice concentration of protein and the resonance angle shift. 1000 resonance units (RU) corre ond to a 0.1° shift in the SPR angle and this is equivalent to a surfiice concentration change of about 1 ng mmr. ... 

By continuously monitoring the SPR response, e q)ressed in resonance units (RU), in the detected volume and plotting this value against time a sensorgram is obtained. 

The signal is measured in terms of resonance units (RU) and the mathematical treatment is as described above. An increase in RU signal is proportional to the concentration of complex AB. The maximum of the specific change in signal then corresponds to a complete saturation of the immobilized ligand. 

For the same reasons, allylic and ben llc halides show high reactivity towards the S, 1 reaction. The carbocahon thus formed gets stabilised through resonance (Unit 12, Class XI) as shown below ... 

Figure 10.4 Binding diagram of LDH, GAPDH, pyruvate kinase and DHODH to the derivatized BIAcore chip at different protein concentrations (x-axis protein concentration, y-axis resonance units).

MRC Biochemical and Clinical Magnetic Resonance Unit, John Radcliffe Hospital, Headington, Oxford, 0X3 9DU, UK... 

Data obtained from biosensors are usually affected by the position on the resonance unit scale, noise, non-specific responses and other artifacts that complicate further presentation. Therefore raw data need to be processed to ensure their comparability. Although many different SPR-based platforms have been developed and data processing can differ slightly, the basic procedures described in this section can be applied with minor adjustments to most of them. Given the importance of data processing, we take time here to describe the general procedures before delving into specific biosensor applications. 

This proposition needs some explanation. The peptide backbone of proteins is formed of a periodic repetition of small resonating units... 

To understand the resonance of the peptide bond, consider first the two extreme forms in which this double bond may exist the covalent and the ionic. In active polypeptide bonds, neither the covalent nor the ionic form exists, but the two types form a resonating unit, as is expected from the resonance theory. 

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