Imaging of Enzyme Activity by Electron Paramagnetic Resonance: Concept and Experiment Using a Paramagnetic Substrate of Alkaline Phosphatase

Sanzhaeva, Urikhan; Xu, Xuan; Guggilapu, PriyaankaDevi; Tseytlin, Mark; Khramtsov, Valery V.; Driesschaert, Benoît

doi:10.1002/anie.201806851

Cited by 12 publications

(11 citation statements)

References 28 publications

(43 reference statements)

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“…In fact, the obtained sensitivity (8.00×10 −5 U/mL) is of the same order of magnitude of the values achieved with optical methods and is significantly enhanced with respect the use of shifting nitroxides, labeled with fatty acids, that split the EPR signal in 6 instead of 3 [5] . Finally, the method has the potential to be translated to in vivo applications via OMRI (Overhauser Magnetic Resonance Imaging) protocols [2–6,35–37] . For this application, the use of probes characterized by narrow EPR signals is crucial to provide high sensitivity and specificity in the polarization transfer from electrons to water protons.…”

Section: Discussionmentioning

confidence: 77%

“…The esterification reaction of tempo derivatives with lauroyl chloride was carried out in a one‐step [9] reaction using pyridine as a base and in a two‐step process, [4] through enolate formation, using lithium diisopropyl amide (LDA) as a strong base to obtain compound T‐C12 and T‐2‐C12, respectively (Scheme 1). The compounds were obtained in good/moderate yields after purification by silica gel chromatography (74 % and 60 % respectively).…”

Section: Resultsmentioning

confidence: 99%

“…Although EPR is recognized as a modality characterized by a good sensitivity, it has not yet found widespread application in the field of enzymatic assays. Only in recent years, its potential has been exploited in body fluids in assays designed to test the activity of the following enzymes: elastase, [2,3] alkaline phosphatase, [4] lipases [5] and cathepsin G [6] . The proposed approach invariantly relies on the use of nitroxide‐containing substrates that the enzyme transforms into products whose phosphorous hyperfine constant is different from the parent species.…”

Section: Introductionmentioning

confidence: 99%

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Highly Sensitive “Off/On” EPR Probes to Monitor Enzymatic Activity

Elkhanoufi

Stefanìa

Alberti

et al. 2022

Chemistry A European J

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The assessment of unregulated level of enzyme activity is a crucial parameter for early diagnoses in a wide range of pathologies. In this study, we propose the use of electron paramagnetic resonance (EPR) as an easy method to probe carboxylesterase (CE) enzymatic activity in vitro. For this application, were synthesized two amphiphilic, nitroxide containing esters, namely Tempo‐C12 (T‐C12) and Tempo‐2‐C12 (T‐2‐C12). They exhibit low solubility in water and form stable micelles in which the radicals are EPR almost silent, but the hydrolysis of the ester bond yields narrows and intense EPR signals. The intensity of the EPR signals is proportional to the enzymatic activity. CEs1, CEs2 and esterase from porcine liver (PLE) were investigated. The obtained results show that T‐C12 and T‐2‐C12‐containing systems display a much higher selectivity toward the CEs2, with a Limit of Detection of the same order of those ones obtained with optical methods.

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Section: Discussionmentioning

confidence: 77%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Highly Sensitive “Off/On” EPR Probes to Monitor Enzymatic Activity

Elkhanoufi

Stefanìa

Alberti

et al. 2022

Chemistry A European J

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“…Work at the University of Denver along with the University of Maryland [7][8][9][10][11][12], the Ohio State University [13][14][15][16][17][18], Dartmouth [19][20][21][22][23], the University of Chicago [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42], and the NIH [43][44][45][46][47][48][49][50][51] continues to demonstrate the utility of low-field EPR for pre-clinical EPR imaging. Expansion of these efforts continues at West Virginia University under the guidance of Tseytlin, Driesschaert and Khramtsov [52][53][54]…”

Section: Contributions To the Low Magnetic Field At The University Of Denvermentioning

confidence: 99%

EPR Everywhere

Biller

McPeak

2021

Appl Magn Reson

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This review is inspired by the contributions from the University of Denver group to low-field EPR, in honor of Professor Gareth Eaton's 80th birthday. The goal is to capture the spirit of innovation behind the body of work, especially as it pertains to development of new EPR techniques. The spirit of the DU EPR laboratory is one that never sought to limit what an EPR experiment could be, or how it could be applied. The most well-known example of this is the development and recent commercialization of rapid-scan EPR. Both of the Eatons have made it a point to remain knowledgeable on the newest developments in electronics and instrument design. To that end, our review touches on the use of miniaturized electronics and applications of single-board spectrometers based on software-defined radio (SDR) implementations and single-chip voltage-controlled oscillator (VCO) arrays. We also highlight several non-traditional approaches to the EPR experiment such as an EPR spectrometer with a "wand" form factor for analysis of the OxyChip, the EPR-MOUSE which enables non-destructive in situ analysis of many non-conforming samples, and interferometric EPR and frequency swept EPR as alternatives to classical high Q resonant structures.

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“…Functional information is encoded into an additional spectral and/or temporal dimension [22][23]. As a result, the images become four or even five-dimensional [24]. Rapid scan (RS) EPR is the method of choice for spectral-spatial imaging, especially when multi-line spin probes are used.…”

Section: Introductionmentioning

confidence: 99%

Rapid Scan EPR Imaging as a Tool for Magnetic Field Mapping

2020

Self Cite

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Functional four-dimensional spectral-spatial electron paramagnetic imaging (EPRI) is routinely used in biomedical research. Positions and widths of EPR lines in the spectral dimension report oxygen partial pressure, pH, and other important parameters of the tissue microenvironment. Images are measured in the homogeneous external magnetic field. An application of EPRI is proposed in which the field is perturbed by a magnetized object. A proof-of-concept imaging experiment was conducted, which permitted visualization of the magnetic field created by this object. A single-line lithium octa-n-butoxynaphthalocyanine spin probe was used in the experiment. The spectral position of the EPR line directly measured the strength of the perturbation field with spatial resolution. A three-dimensional magnetic field map was reconstructed as a result. Several applications of this technology can be anticipated. First is EPRI/MPI co-registration, where MPI is an emerging magnetic particle imaging technique. Second, EPRI can be an alternative to magnetic field cameras that are used for the development of high-end permanent magnets and their assemblies, consumer electronics, and industrial sensors. Besides the high resolution of magnetic field readings, EPR probes can be placed in the internal areas of various assemblies that are not accessible by the standard sensors. Third, EPRI can be used to develop systems for magnetic manipulation of cell cultures.

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Imaging of Enzyme Activity by Electron Paramagnetic Resonance: Concept and Experiment Using a Paramagnetic Substrate of Alkaline Phosphatase

Cited by 12 publications

References 28 publications

Highly Sensitive “Off/On” EPR Probes to Monitor Enzymatic Activity

Highly Sensitive “Off/On” EPR Probes to Monitor Enzymatic Activity

EPR Everywhere

Rapid Scan EPR Imaging as a Tool for Magnetic Field Mapping

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