Liquid helium system

Manufactured by Oxford Instruments

The Liquid Helium System is a specialized laboratory equipment designed to provide a stable and controlled source of liquid helium. Liquid helium is a cryogenic fluid with an extremely low boiling point, which is essential for a variety of scientific and industrial applications that require ultra-low temperatures. The core function of the Liquid Helium System is to store, manage, and deliver liquid helium to support these applications.

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Lab products found in correlation

Sq epr tubes, by Wilmad (3 mentions) Sp9703, by Oxford Instruments (2 mentions) Emx epr spectrometer, by Bruker (1 mentions) Pd 10 desalting column, by GE Healthcare (1 mentions) V500 spectrometer, by Jasco (1 mentions) Compass data analysis version 4, by Bruker (1 mentions) Microtof qiii mass spectrometer, by Bruker (1 mentions) Esi l low concentration tuning mix, by Agilent Technologies (1 mentions) J 810 spectropolarimeter, by Jasco (1 mentions)

5 protocols using liquid helium system

Kinetic Analysis of Cygb Oxidation

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Monomeric WT, H81V and H81Y Cygb (80 μM) in 20 mM sodium phosphate buffer (pH 7.4) were reacted with hydrogen peroxide, either at 1:1 at (80 μM) or 1:10 (800 μM) protein:hydrogen peroxide ratio in Wilmad SQ EPR tubes (Wilmad Glass). The reaction was halted by flash-freezing in dry ice cooled methanol at various time points (0, 20, 45, 90, 180 s). The samples were stored in liquid nitrogen (77 K) prior to measurement. Electron paramagnetic resonance (EPR) spectra were taken using a Bruker EMX EPR spectrophotometer (X-band) equipped with a spherical high-quality resonator SP9703 and an Oxford Instruments liquid helium system. The modulation frequency was 100 kHz. Accurate
g values were obtained using the built-in microwave frequency counter and a 2,2-diphenyl-1-picrylhydrazyl powder standard, the
g value for which is g = 2.0027 ± 0.0002
^{22 ,
23 (link)}.

Beckerson P., Svistunenko D, & Reeder B. (2015). Effect of the distal histidine on the peroxidatic activity of monomeric cytoglobin. F1000Research, 4, 87.

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Sorghum Peroxidase EPR Spectroscopy

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Aliquots of sorghum peroxidase (sodium phosphate buffer, pH 6) were frozen in Wilmad SQ EPR tubes (Wilmad LabGlass, Vineland, NJ, USA) in methanol kept on dry ice. The EPR spectra of the frozen samples were recorded at 10 K on a Bruker EMX spectrometer (X-band) equipped with a spherical high-quality ER 4122 SP9703 resonator and an Oxford Instruments liquid helium system.

Nnamchi C.I., Parkin G., Efimov I., Basran J., Kwon H., Svistunenko D.A., Agirre J., Okolo B.N., Moneke A., Nwanguma B.C., Moody P.C, & Raven E.L. (2015). Structural and spectroscopic characterisation of a heme peroxidase from sorghum. Journal of Biological Inorganic Chemistry, 21, 63-70.

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Quantifying Rhombic Ferric Iron by EPR

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The method was derived from (34 (link), 64 (link)). Cells were grown in LB to an OD of ∼0.2 before centrifugation at 7800 g at room temperature and concentrated 200- to 300-fold before incubation at 37°C for 15 min in 20 mM desferrioxamine. Cells were again centrifuged, washed with cold 20 mM Tris (pH 7.4), and resuspended in a final volume of ∼0.5 ml Tris/10% glycerol. Aliquots (0.3 ml) were placed in EPR tubes, which were flash-frozen in methanol kept on dry ice. EPR measurements were performed at 10 K on a Bruker EMX EPR spectrometer equipped with a spherical high-quality Bruker resonator SP9703 and an Oxford Instruments liquid helium system for low temperature measurements. To measure intensities of the g = 4.3 EPR signal from rhombic ferric iron, the procedure of spectral subtraction with a variable coefficient was used (64 (link)).

Wareham L.K., Begg R., Jesse H.E., van Beilen J.W., Ali S., Svistunenko D., McLean S., Hellingwerf K.J., Sanguinetti G, & Poole R.K. (2016). Carbon Monoxide Gas Is Not Inert, but Global, in Its Consequences for Bacterial Gene Expression, Iron Acquisition, and Antibiotic Resistance. Antioxidants & Redox Signaling, 24(17), 1013-1028.

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Biophysical Characterization of RsrR Protein

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UV-visible absorbance measurements were performed using a Jasco V500 spectrometer, and CD spectra were measured with a Jasco J810 spectropolarimeter. EPR measurements were performed at 10 K using a Bruker EMX EPR spectrometer (X-band) equipped with a liquid helium system (Oxford Instruments). Spin concentrations in the protein samples were estimated by double integration of EPR spectra with reference to a 1 mM Cu(II) in 10 mM EDTA standard. For native MS analysis, His-tagged RsrR was exchanged into 250 mM ammonium acetate, pH 8, using PD10 desalting columns (GE Life Sciences), diluted to ~21 μM cluster and infused directly (0.3 mL/h) into the ESI source of a Bruker micrOTOF-QIII mass spectrometer (Bruker Daltonics, Coventry, UK) operating in the positive ion mode. Full mass spectra (m/z 700–3500) were recorded for 5 min. Spectra were combined, processed using the ESI Compass version 1.3 Maximum Entropy deconvolution routine in Bruker Compass Data analysis version 4.1 (Bruker Daltonik, Bremen, Germany). The mass spectrometer was calibrated with ESI-L low concentration tuning mix in the positive ion mode (Agilent Technologies, San Diego, CA).

Munnoch J.T., Martinez M.T., Svistunenko D.A., Crack J.C., Le Brun N.E, & Hutchings M.I. (2016). Characterization of a putative NsrR homologue in Streptomyces venezuelae reveals a new member of the Rrf2 superfamily. Scientific Reports, 6, 31597.

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EPR Characterization of GlxA Protein

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GlxA samples (85-120 μM) for EPR were prepared in duplicate in a mixed buffer system consisting of 10 mM each of Tris, potassium acetate, MES, MOPS and 200 mM KCl with the pH adjusted to 7.0. Wilmad SQ EPR tubes (Wilmad Glass) were filled with the GlxA solutions and frozen in methanol kept on dry ice. The tubes were then transferred to liquid nitrogen. All EPR spectra were measured on a Bruker EMX EPR spectrometer (X band). A spherical high-quality Bruker resonator ER 4122 SP 9703 and an Oxford Instruments liquid helium system were used to measure the low-temperature EPR spectra. Digitizing of a published EPR spectrum was performed using Un-Scan-It, v.6, Silk Scientific.

Chaplin A.K., Petrus M.L., Mangiameli G., Hough M.A., Svistunenko D.A., Nicholls P., Claessen D., Vijgenboom E, & Worrall J.A. (2015). GlxA is a new structural member of the radical copper oxidase family and is required for glycan deposition at hyphal tips and morphogenesis of Streptomyces lividans. The Biochemical journal, 469(3).

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