Enzymes, activity, imaging

Razgulin A. Ma N. Rao J. Strategies for in vivo imaging of enzyme activity An overview and recent advances. Chemical Society Reviews, 2011,40,4186-4216. 

Part of the reason may be the relatively crude nature of the tools we have had until recently to study brain function. However, this is clearly beginning to change. Genetic research and functional brain imaging, which actually takes pictures of the brain in action, may ultimately give us a glimpse of brain receptor and enzyme activity that was unthinkable just a few years ago. 

A very useful complement to enzyme assays as described above is histochemical study, which can provide additional information [76]. In particular, because it is possible to measure the activity cell per cell, histochemistry permits, in the case of a heteroplasmic population of mitochondria, the detection of even a small number of affected cells, which may have remained undetected by biochemical assays. Spectacular images showing, side-by-side, cells endowed with either high or absent enzyme activity can be obtained. The limitation of the method is in part due to the few activities possibly measured (essentially complex IV, succinic dehydrogenase, and less specifically, ATPase and NADH reductase) and to the fact that it is poorly quantitative. Histochemical investigations are performed under selected conditions (e.g., substrate concentrations, pH), which often differ from those used for enzyme assays, thus possibly introducing discrepancy between the two approaches. 

SECM imaging of local enzyme activities in GC mode... 

The concentrations of the enzyme substrate have to be selected with some care. In the GC experiment, it should be well above the Michaelis-Menten constant of the enzyme for this substrate. The presence of the UME with its sheath will also limit the diffusion of the enzyme substrate towards the active regions. This may lead to an underestimation of enzyme activity on the surface or to great distorsion in recorded images. Using electrodes with a small RG is a good idea for GC experiments. This question is explained in Procedure 52 (see in CD accompanying this book). 

Imaging of Biomolecules Using the Europium(lll) Tetracycline Probe Determination of Glucose, Enzyme Activities, and ELISAs... 

The [Eu(Tc)] assay for H202 can also be used for the determination of enzyme activities. This comprises all enzymes that produce (oxidases) or consume (catalase, peroxidases) H2O2. For example, the activity of glucose oxidase can be directly imaged after the addition of [Eu(Tc)] as indicator and glucose as substrate. Steady-state and time-resolved imaging schemes can be applied for the read-out of a microwell plate-based assay. The best results were obtained by the RLI method (Fig. 19) [115]. 

Kidney Renal RAS Mouse model MALDI-TOF/ TOF-MS Molecular imaging of renal RAS Localization of AngW and enzymes activity in kidney regions (61)... 

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