The measurement of spin-lattice relaxation rates from spin labels, such as nitroxides, in the presence and absence of spin relaxants provides information that is useful for determining biomolecular properties such as nucleic acid dynamics and the interaction of proteins with membranes. We compare X-band continuous wave (CW) and pulsed or time domain (TD) EPR methods for obtaining spin-lattice relaxation rates of spin labels across the entire range of rotational motion to which relaxation rates are sensitive. Model nitroxides and spin-labeled biological species are used to illustrate the potential complications that arise in extracting relaxation data under conditions typical to biological experiments. The effect of super hyperfine (SHF) structure is investigated for both CW and TD spectra. First and second harmonic absorption and dispersion CW spectra of the nitroxide spin label, TEMPOL, are all fit simultaneously to a model of SHF structure over a range of microwave amplitudes. The CW spectra are novel because all harmonics and microwave phases were acquired simultaneously using our homebuilt CW/TD spectrometer. The effect of the SHF structure on the pulsed free induction decay (FID) and pulsed saturation recovery spectrum is shown for both protonated and deuterated TEMPOL. We present novel pulsed saturation recovery measurements on biological molecules, including spin-lattice relaxation rates of spin-labeled proteins and spin-labeled double-stranded DNA. The impact of structure and dynamics on relaxation rates are discussed in the context of each of these examples. Collisional relaxation rates with oxygen and transition metal paramagnetic relaxants are extracted using both continuous wave and time domain methods. The extent of the errors inherent in the CW method and the advantages of pulsed methods for unambiguously measuring collisional relaxation rates are discussed. Spin-lattice relaxation rates, determined by both CW and pulsed methods, are used to determine the electrostatic potential on the surface of a protein.
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http://dx.doi.org/10.1016/j.jmr.2004.04.010 | DOI Listing |
Sci Rep
January 2025
U.S. Department of Agriculture, Agricultural Research Service, Beltsville, MD, 20705, USA.
Thermoinhibition, the suppression of seed germination by high temperatures, is an adaptive trait that ensures successful seedling establishment in natural environments. While beneficial for wild plants, thermoinhibition can adversely affect crop yields due to uneven and reduced germination rates, particularly in the face of climate change. To understand the genetic basis of thermoinhibition, we conducted a comprehensive genetic analysis of a diverse panel of Lactuca spp.
View Article and Find Full Text PDFBMC Infect Dis
January 2025
Basque Center for Applied Mathematics, Bilbao, Bizkaia, Spain.
Background: COVID-19, caused by SARS-CoV-2, has spread globally, presenting a significant public health challenge. Vaccination has played a critical role in reducing severe disease and deaths. However, the waning of immunity after vaccination and the emergence of immune-escape variants require the continuation of vaccination efforts, including booster doses, to maintain population immunity.
View Article and Find Full Text PDFCureus
December 2024
General Medicine, Kalinga Institute of Medical Sciences, Bhubaneswar, IND.
Autonomous sensory meridian response (ASMR) is a sensory phenomenon characterized by tingling sensations triggered by specific auditory or visual stimuli, offering a novel approach to anxiety reduction and relaxation. This review explores the therapeutic potential of ASMR in orthodontics by examining its physiological and psychological benefits, neuroscientific basis, and its potential to enhance patient comfort, manage dental anxiety, and improve communication within orthodontic practice. A comprehensive literature review was conducted to evaluate studies on ASMR's physiological, psychological, and clinical effects, focusing on ASMR-induced relaxation, patient-specific triggers, and its integration into orthodontic settings.
View Article and Find Full Text PDFBiomech Model Mechanobiol
December 2024
Bioengineering, University of California, Santa Barbara, Santa Barbara, United States.
The heart is a dynamic pump whose function is influenced by its mechanical properties. The viscoelastic properties of the heart, i.e.
View Article and Find Full Text PDFNeurogastroenterol Motil
December 2024
Trisco Foods, Carole Park, Queensland, Australia.
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