Citation M. H. Garrett, V. H. Chan, H. P. Jenssen, M. H. Whitmore, A. Sacra, D. J. Singel, and D.... more Citation M. H. Garrett, V. H. Chan, H. P. Jenssen, M. H. Whitmore, A. Sacra, D. J. Singel, and D. J. Simkin, "Comparison of Chromium-Doped Forsterite and Åkermanite Laser Host Crystals," in Advanced Solid State Lasers, G. Dube and L. Chase, eds., Vol. 10 of OSA Proceedings Series (Optical Society of America, 1991), paper C4L12. http://www.opticsinfobase.org/abstract.cfm?URI=ASSL-1991-C4L12
Optical Zeeman experiments were performed on Cr:forsterite with the magnetic field applied along ... more Optical Zeeman experiments were performed on Cr:forsterite with the magnetic field applied along the crystallographic a and c axes. The strong agreement between these optical results and previous EPR studies for both alignments establishes the identity of the near infrared emission center as tetrahedral Cr4+.
ABSTRACT Optical Zeeman spectra of the near-IR luminescent center in Cr:forsterite were obtained ... more ABSTRACT Optical Zeeman spectra of the near-IR luminescent center in Cr:forsterite were obtained with an external magnetic field applied along the crystallographic a and c axes. The field-dependent sublevel splittings of the triplet spin ground state were resolved through fluorescence line narrowing (FLN) techniques. The excellent correspondence between the observed splittings and those calculated for the tetrahedral Cr4+ center, previously identified and characterized in forsterite by electron paramagnetic resonance, firmly establishes the identity of the near-IR center as tetrahedral Cr4+. A simple model for the FLN excitation-emission cycle, including the influence of the external field on the optical line positions and intensities, is described.
ABSTRACT We report a 13C DNP NMR study of the organic conductor fluoranthenyl (FA) radical cation... more ABSTRACT We report a 13C DNP NMR study of the organic conductor fluoranthenyl (FA) radical cation salt (FA)2+PF6−. We have been able to suppress the Knight shift by saturating the ESR line. Overhauser enhancements achieved were large enough to detect 1016 carbons after 1 s of microwave saturation.
Congeners of nitrogen monoxide (NO) are neuroprotective and neurodestructive. To address this app... more Congeners of nitrogen monoxide (NO) are neuroprotective and neurodestructive. To address this apparent paradox, we considered the effects on neurons of compounds characterized by alternative redox states of NO: nitric oxide (NO.) and nitrosonium ion (NO+). Nitric oxide, generated from NO. donors or synthesized endogenously after NMDA (N-methyl-D-aspartate) receptor activation, can lead to neurotoxicity. Here, we report that NO.- mediated neurotoxicity is engendered, at least in part, by reaction with superoxide anion (O2.-), apparently leading to formation of peroxynitrite (ONOO-), and not by NO. alone. In contrast, the neuroprotective effects of NO result from downregulation of NMDA-receptor activity by reaction with thiol group(s) of the receptor's redox modulatory site. This reaction is not mediated by NO. itself, but occurs under conditions supporting S-nitrosylation of NMDA receptor thiol (reaction or transfer of NO+). Moreover, the redox versatility of NO allows for its in...
Nitric oxide (NO.), a potentially toxic molecule, has been implicated in a wide range of biologic... more Nitric oxide (NO.), a potentially toxic molecule, has been implicated in a wide range of biological functions. Details of its biochemistry, however, remain poorly understood. The broader chemistry of nitrogen monoxide (NO) involves a redox array of species with distinctive properties and reactivities: NO+ (nitrosonium), NO., and NO- (nitroxyl anion). The integration of this chemistry with current perspectives of NO biology illuminates many aspects of NO biochemistry, including the enzymatic mechanism of synthesis, the mode of transport and targeting in biological systems, the means by which its toxicity is mitigated, and the function-regulating interaction with target proteins.
A three step protocol for protein S-nitrosothiol conversion to fluorescent mixed disulfides with ... more A three step protocol for protein S-nitrosothiol conversion to fluorescent mixed disulfides with purified proteins, referred to as the thiosulfonate switch, is explored which involves: (1) thiol blocking at pH 4.0 using S-phenylsulfonylcysteine (SPSC); (2) trapping of protein S-nitrosothiols as their S-phenylsulfonylcysteines employing sodium benzenesulfinate; and (3) tagging the protein thiosulfonate with a fluorescent rhodamine based probe bearing a reactive thiol (Rhod-SH), which forms a mixed disulfide between the probe and the formerly S-nitrosated cysteine residue. S-Nitrosated bovine serum albumin and the S-nitrosated C-terminally truncated form of AdhR-SH (alcohol dehydrogenase regulator) designated as AdhR*-SNO were selectively labelled by the thiosulfonate switch both individually and in protein mixtures containing free thiols. This protocol features the facile reaction of thiols with S-phenylsulfonylcysteines forming mixed disulfides at mild acidic pH (pH = 4.0) in both t...
Citation M. H. Garrett, V. H. Chan, H. P. Jenssen, M. H. Whitmore, A. Sacra, D. J. Singel, and D.... more Citation M. H. Garrett, V. H. Chan, H. P. Jenssen, M. H. Whitmore, A. Sacra, D. J. Singel, and D. J. Simkin, "Comparison of Chromium-Doped Forsterite and Åkermanite Laser Host Crystals," in Advanced Solid State Lasers, G. Dube and L. Chase, eds., Vol. 10 of OSA Proceedings Series (Optical Society of America, 1991), paper C4L12. http://www.opticsinfobase.org/abstract.cfm?URI=ASSL-1991-C4L12
Optical Zeeman experiments were performed on Cr:forsterite with the magnetic field applied along ... more Optical Zeeman experiments were performed on Cr:forsterite with the magnetic field applied along the crystallographic a and c axes. The strong agreement between these optical results and previous EPR studies for both alignments establishes the identity of the near infrared emission center as tetrahedral Cr4+.
ABSTRACT Optical Zeeman spectra of the near-IR luminescent center in Cr:forsterite were obtained ... more ABSTRACT Optical Zeeman spectra of the near-IR luminescent center in Cr:forsterite were obtained with an external magnetic field applied along the crystallographic a and c axes. The field-dependent sublevel splittings of the triplet spin ground state were resolved through fluorescence line narrowing (FLN) techniques. The excellent correspondence between the observed splittings and those calculated for the tetrahedral Cr4+ center, previously identified and characterized in forsterite by electron paramagnetic resonance, firmly establishes the identity of the near-IR center as tetrahedral Cr4+. A simple model for the FLN excitation-emission cycle, including the influence of the external field on the optical line positions and intensities, is described.
ABSTRACT We report a 13C DNP NMR study of the organic conductor fluoranthenyl (FA) radical cation... more ABSTRACT We report a 13C DNP NMR study of the organic conductor fluoranthenyl (FA) radical cation salt (FA)2+PF6−. We have been able to suppress the Knight shift by saturating the ESR line. Overhauser enhancements achieved were large enough to detect 1016 carbons after 1 s of microwave saturation.
Congeners of nitrogen monoxide (NO) are neuroprotective and neurodestructive. To address this app... more Congeners of nitrogen monoxide (NO) are neuroprotective and neurodestructive. To address this apparent paradox, we considered the effects on neurons of compounds characterized by alternative redox states of NO: nitric oxide (NO.) and nitrosonium ion (NO+). Nitric oxide, generated from NO. donors or synthesized endogenously after NMDA (N-methyl-D-aspartate) receptor activation, can lead to neurotoxicity. Here, we report that NO.- mediated neurotoxicity is engendered, at least in part, by reaction with superoxide anion (O2.-), apparently leading to formation of peroxynitrite (ONOO-), and not by NO. alone. In contrast, the neuroprotective effects of NO result from downregulation of NMDA-receptor activity by reaction with thiol group(s) of the receptor's redox modulatory site. This reaction is not mediated by NO. itself, but occurs under conditions supporting S-nitrosylation of NMDA receptor thiol (reaction or transfer of NO+). Moreover, the redox versatility of NO allows for its in...
Nitric oxide (NO.), a potentially toxic molecule, has been implicated in a wide range of biologic... more Nitric oxide (NO.), a potentially toxic molecule, has been implicated in a wide range of biological functions. Details of its biochemistry, however, remain poorly understood. The broader chemistry of nitrogen monoxide (NO) involves a redox array of species with distinctive properties and reactivities: NO+ (nitrosonium), NO., and NO- (nitroxyl anion). The integration of this chemistry with current perspectives of NO biology illuminates many aspects of NO biochemistry, including the enzymatic mechanism of synthesis, the mode of transport and targeting in biological systems, the means by which its toxicity is mitigated, and the function-regulating interaction with target proteins.
A three step protocol for protein S-nitrosothiol conversion to fluorescent mixed disulfides with ... more A three step protocol for protein S-nitrosothiol conversion to fluorescent mixed disulfides with purified proteins, referred to as the thiosulfonate switch, is explored which involves: (1) thiol blocking at pH 4.0 using S-phenylsulfonylcysteine (SPSC); (2) trapping of protein S-nitrosothiols as their S-phenylsulfonylcysteines employing sodium benzenesulfinate; and (3) tagging the protein thiosulfonate with a fluorescent rhodamine based probe bearing a reactive thiol (Rhod-SH), which forms a mixed disulfide between the probe and the formerly S-nitrosated cysteine residue. S-Nitrosated bovine serum albumin and the S-nitrosated C-terminally truncated form of AdhR-SH (alcohol dehydrogenase regulator) designated as AdhR*-SNO were selectively labelled by the thiosulfonate switch both individually and in protein mixtures containing free thiols. This protocol features the facile reaction of thiols with S-phenylsulfonylcysteines forming mixed disulfides at mild acidic pH (pH = 4.0) in both t...
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