Solid-State Tunable kHz Ultraviolet Laser for Raman Applications

Zhao, Xiaojie; Chen, Ruopian; Tengroth, Charbel; Spiro, Thomas G.

doi:10.1366/0003702991945669

Cited by 43 publications

(65 citation statements)

References 20 publications

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“…Time-resolved Resonance Raman Spectroscopy-The experimental setup for the time-resolved resonance Raman measurements has been described elsewhere (21,22). The second harmonic of a Q-switched Nd:YLF laser (Photonics International GM-30-527) was used to pump a Ti:sapphire laser (Photonics International TU-UV), which gave a narrowed laser frequency output (Ͻ0.1 cm Ϫ1 ) tunable between 810 and 920 nm.…”

Section: Methodsmentioning

confidence: 99%

Dynamics of Carbon Monoxide Binding to CooA

Puranik

Nielsen

Youn

et al. 2004

Journal of Biological Chemistry

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Section: Methodsmentioning

confidence: 99%

Dynamics of Carbon Monoxide Binding to CooA

Puranik

Nielsen

Youn

et al. 2004

Journal of Biological Chemistry

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“…36 Figure 4 presents the REPs of tyrosine (Y8a) and tryptophan (W16) in PYP dark and in aqueous amino acids. 43 The REPs for tyrosine and tryptophan in PYP dark are red-shifted (∼900 cm -1 ) as a result of the protein environment, which lowers the energy of the resonant electronic transitions. Similar red shifts of the REP for tyrosine and tryptophan are observed in other proteins such as hemoglobin.…”

Section: Methodsmentioning

confidence: 99%

Structural Changes during the Photocycle of Photoactive Yellow Protein Monitored by Ultraviolet Resonance Raman Spectra of Tyrosine and Tryptophan

et al. 2005

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Photoactive yellow protein (PYP) is a bacterial blue light photoreceptor, and photoexcitation of dark-state PYP (PYP(dark)) triggers a photocycle that involves several intermediate states. We report the ultraviolet resonance Raman spectra of PYP with 225-250 nm excitations and investigate protein structural changes accompanying the formation of the putative signaling state denoted PYP(M). The PYP(M)-PYP(dark) difference spectra show several features of tyrosine and tryptophan, indicating environmental changes for these amino acid residues. The tyrosine difference signals show small upshifts with intensity changes in Y8a and Y9a bands. Although there are five tyrosine residues in PYP, Tyr42 and Tyr118 are suggested to be responsible for the difference signals on the basis of a global fitting analysis of the difference spectra at different excitation wavelengths and the crystal structure of PYP(dark). A further experiment on the Thr50-->Val mutant supports environmental changes in Tyr42. The observed upshift of the Y8a band suggests a weaker or broken hydrogen bond between Tyr42 and the chromophore in PYP(M). In addition, a reorientation of the OH group in Tyr42 is suggested from the upshift of the Y9a band. For tryptophan, the Raman bands of W3, W16, and W18 modes diminish in intensity upon formation of PYP(M). The loss of intensities is attributable to an exposure of tryptophan in PYP(M). PYP contains only one tryptophan (Trp119) that is located more than 10 A from the active site. Thus the observed changes are indicative of global conformational changes in protein during the transition from PYP(dark) to PYP(M). These results are in line with the currently proposed photocycle mechanism of PYP.

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“…Time-resolved Resonance Raman Measurements of Photorecombination-The set-up has been described in detail previously (14,15). The second harmonic of a Q-switched Nd:YLF laser (Photonics International GM-30-527) was used to pump a Ti:sapphire laser (Photonics International TU-UV) that gave a narrowed laser frequency output (Ͻ0.1 cm…”

Section: Stopped Flow Measurements Of Co Associationmentioning

confidence: 99%

Dynamics of Carbon Monoxide Binding to Cystathionine β-Synthase

Puranik

Weeks

Lahaye

et al. 2006

Journal of Biological Chemistry

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Cystathionine ␤-synthase (CBS) condenses homocysteine, a toxic metabolite, with serine in a pyridoxal phosphate-dependent reaction. It also contains a heme cofactor to which carbon monoxide (CO) or nitric oxide can bind, resulting in enzyme inhibition. To understand the mechanism of this regulation, we have investigated the equilibria and kinetics of CO binding to the highly active catalytic core of CBS, which is dimeric. CBS exhibits strong anticooperativity in CO binding with successive association constants of 0.24 and 0.02 M ؊1 . Stopped flow measurements reveal slow CO association (0.0166 s ؊1 ) limited by dissociation of the endogenous ligand, Cys-52. Rebinding of CO and of Cys-52 following CO photodissociation were independently monitored via time-resolved resonance Raman spectroscopy. The Cys-52 rebinding rate, 4000 s ؊1 , is essentially unchanged between pH 7.6 and 10.5, indicating that the pK a of Cys-52 is shifted below pH 7.6. This effect is attributed to the nearby Arg-266 residue, which is proposed to form a salt bridge with the dissociated Cys-52, thereby inhibiting its protonation and slowing rebinding to the Fe. This salt bridge suggests a pathway for enzyme inactivation upon CO binding, because Arg-266 is located on a helix that connects the heme and pyridoxal phosphate cofactor domains.

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Solid-State Tunable kHz Ultraviolet Laser for Raman Applications

Cited by 43 publications

References 20 publications

Dynamics of Carbon Monoxide Binding to CooA

Dynamics of Carbon Monoxide Binding to CooA

Structural Changes during the Photocycle of Photoactive Yellow Protein Monitored by Ultraviolet Resonance Raman Spectra of Tyrosine and Tryptophan

Dynamics of Carbon Monoxide Binding to Cystathionine β-Synthase

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