Compound I Formation and Reactivity in Dimeric Chlorite Dismutase: Impact of pH and the Dynamics of the Catalytic Arginine

• Data type: spectroscopic measurements (UV-visible, ECD, EPR), enzyme activity measurements, mass spectrometry, spectroelectrochemistry and data analysis.
• Files are in .DTA, .DSC, .xlsx, .m, .mat, .BSW, .csv, .txt, .dsx, .pdf, .uds formats
• Information on origin of the data:
  • EPR spectroscopic measurements in DTA and DSC formats
  • EPR spectroscopic simulation and analyses in m and mat format
  • Analysis of Rapid Freeze-Quench calibration curve is in xlsx format
  • UV-vis spectroscopic measurements in csv, xlsx, txt, uds and dsx format
  • ECD measurements in csv, xlsx and dsx format
  • Enzyme activity data in csv and xlsx format
  • Mass spectrometry data in pdf and xlsx format
  • Spectroelectrochemistry data in BSW and xlsx format
• The data are generated by:
  • UV−vis spectra were recorded using a Cary 60 UV–vis spectrophotometer (Agilent) and a U-3900 spectrophotometer (Hitachi, Mannheim, Germany).
  • Electronic circular dichroism spectroscopy was performed using Chirascan (Applied Photophysics, Leatherhead, UK).
  • Rapid Freeze-Quench of EPR sample was performed with the use of a device from BioLogic (Grenoble, France), consisting of an SFM-2000 stopped-flow unit and an MPS-70 controller unit, combined with a freeze-quench sample collector adapted for EPR tubes. The ejected volumes and flow rate were controlled by the BioLogic BIOKINE software, v. 4.72.
  • X-Band CW-EPR experiments were performed on X-band ELEXSYS E580 spectrometer (Bruker BioSpin GmbH) operating at a microwave frequency of ∼9.4 GHz and equipped with a standard TE102 cavity and a liquid He cryostat (Oxford Inc.)
  • Enzyme activity was measured polarographically following the release of O₂ by using a Clark-type oxygen electrode (Oxygraph Plus; Hansatech Instruments, Norfolk, UK).
  • Stopped-flow spectroscopy measurements were performed with a SX-18MV or Pi-star from Applied Photophysics using either a diode array detector or a monochromator and photomultiplier detector.
  • Mass spectrometry analysis was performed with an ion-trap mass spectrometer (amaZon speed ETD, Bruker) equipped with the standard ESI source in positive ion, DDA mode (i.e., switching to MSMS mode for eluting peaks).
  • All spectroelectrochemistry experiments were conducted in a homemade OTTLE (optical transparent thin-layer spectroelectrochemical) cell. In detail, the three-electrode configuration consisted of a gold minigrid working electrode (Buckbee-Mears, Chicago, IL), a homemade Ag/AgCl/KCl_sat microreference electrode separated from the working solution by a Vycor set, and a platinum wire as the counter electrode. UV−vis spectra were recorded using a Varian Cary C50 spectrophotometer.

• If the dataset includes multiple files that relate to each other:
  • Files in PARACAT_WP3_20230302_01_EPR folder includes EPR spectroscopic measurements and computer simulations/analyses, original data are in DTA/DSC formats; files in m format were used to process the data.
  • Files in PARACAT_WP3_20230302_02_UVVIS folder includes sequential and non-sequential stopped flow data, measured with detection by photodiode array or monochromator (time traces): original data is in dsx and csv format, xlsx format contains processed data; conventional photometric data is originally in txt and uds format, xlsx format contains processed data
  • Files in PARACAT_WP3_20230302_03_ECD folder contain ECD spectra: original data is in dsx and csv format, xlsx format contains processed data
  • Files in PARACAT_WP3_20230302_04_Enzyme activity folder contain polarographically detected changes in dioxygen concentration, due to enzyme activity: original data is in csv format, xlsx format contains processed data
  • Files in PARACAT_WP3_20230302_05_MassSpec folder contain mass spectrometry data for the MNP assay: original data is in pdf format, xlsx format contains processed data
  • Files in PARACAT_WP3_20230302_06_Spectroelectrochemistry folder includes spectroelectrochemistry measurements and computer analyses, original data are in BSW formats; files in xlsx format were used to process the data.

NB. See the “READ ME” text file in each subfolder for more detailed information on files organization.

• Information on:
  • Abbreviations:
    • , chlorite dismutase; CCld, chlorite dismutase from Cyanothece sp. PCC7425; CcP, cytochrome c peroxidase; DaCld, chlorite dismutase from Dechloromonas aromatica; E°′, standard reduction potential; ECD, electronic circular dichroism; EPR, electron paramagnetic resonance; HRP, horseradish peroxidase; LPO, lactoperoxidase; MNP, 2-methyl-2-nitrosopropane; MPO, myeloperoxidase; PAA, peracetic acid; RFQ, rapid freeze-quench.

• Units of measurement:
  • Concentration: mM (millimolar), µM (micromolar), nM (nanomolar), mg/mL (milligrams per milliliter)
  • Molecular mass: Da (Dalton)
  • Absorptivity: M^-1 cm^-1
  • Volume: mL (milliliters), µL (microliters), nL (nanoliters)
  • Wavelength: nm (nanometers)
  • Temperature: °C (Celsius degrees), K (Kelvin degrees)
  • Time: ms (milliseconds), s (seconds), min (minutes), h (hours),
  • Ellipticity: millidegrees
  • Frequency: GHz (gigahertz), kHz (kilohertz)
  • Power: mW (milliwatt)
  • Magnetic field: mT (milliTesla)
  • Reduction potential: mV (milliVolts)