Resonance Raman study on synergistic activation of soluble guanylate cyclase by imidazole, YC-1 and GTP

Pal, Biswajit; Li, Zhengqiang; Ohta, Takao; Takenaka, Shigeo; Tsuyama, Shingo; Kitagawa, Teizo

doi:10.1016/j.jinorgbio.2003.12.007

Cited by 20 publications

(26 citation statements)

References 34 publications

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“…In a recent work we showed that 1.2 M imidazole treatment to the sGC 2 oxidized the heme and reduction of the ferric enzyme with dithionite produced enzyme similar to sGC 1 [55]. This observation may help to explain the contradictory features.…”

Section: Structure Of Native Sgc In Reduced Formmentioning

confidence: 76%

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Interactions of soluble guanylate cyclase with diatomics as probed by resonance Raman spectroscopy

Pal

Kitagawa

2005

Journal of Inorganic Biochemistry

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Section: Structure Of Native Sgc In Reduced Formmentioning

confidence: 76%

“…These compounds have revealed the presence of previously unknown regulatory sites in the enzyme, which may be physiologically important and may serve as target sites for endogenous molecules modulating sGC activity [66]. Recently, we have shown that YC-1 effect becomes more prominent in the presence of imidazole [55].…”

Section: Other Effectorsmentioning

confidence: 99%

Interactions of soluble guanylate cyclase with diatomics as probed by resonance Raman spectroscopy

Pal

Kitagawa

2005

Journal of Inorganic Biochemistry

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“…Previous RR studies on sGC and the truncated β1 heme domain showed the presence of two CO conformers based on the detection of two Fe-CO stretching frequencies at ~478 and ~487–496 cm −1 (27–30, 33, 36–38). The majority of these results only reported one stretching frequency for ν(C-O); this discrepancy is likely due to the weak intensity inherent to the C-O stretching mode in RR spectra and the difficulty in obtaining large quantities of full length sGC.…”

Section: Resultsmentioning

confidence: 98%

Determinants of the Heme–CO Vibrational Modes in the H-NOX Family

et al. 2011

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The H-NOX family of proteins have important functions in gaseous ligand signaling in organisms from bacteria to humans, including nitric oxide (NO) sensing in mammals, and provide a model system for probing ligand selectivity in hemoproteins. A unique vibrational feature that is ubiquitous throughout the Heme-Nitric oxide/OXygen binding (H-NOX) family is the presence of a high C-O stretching frequency. To investigate the cause of this spectroscopic characteristic, the Fe-CO and C-O stretching frequencies were probed in the H-NOX domain from Thermoanaerobacter tengcongensis (Tt H-NOX) using resonance Raman (RR) spectroscopy. Four classes of heme pocket mutants were generated to assess the changes in stretching frequency: (i) the distal H-bonding network, (ii) the proximal histidine ligand, (iii) modulation of the heme conformation via Ile-5 and Pro-115, and (iv) the conserved Tyr-Ser-Arg (YxSxR) motif. These mutations revealed important electrostatic interactions that dampen the back-donation of the FeII dπ electrons into the CO π* orbitals. The most significant change occurred upon disruption of the H-bonds between the strictly conserved YxSxR motif and the heme propionate groups, producing two dominant CO-bound heme conformations. One conformer was structurally similar to Tt H-NOX WT; whereas the other displayed a decrease in ν(C-O) of up to ~70 cm−1 relative to the WT protein, with minimal changes in ν(Fe-CO). Taken together, these results show that the electrostatic interactions in the Tt H-NOX binding pocket are primarily responsible for the high ν(C-O) by decreasing the Fe dπ → CO π* back-donation, and suggest that the dominant mechanism by which this family modulates the FeII-CO bond likely involves the YxSxR motif.

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“…Even though the spectrum was measured at an extremely low laser power (ϳ0.05 milliwatt), its intensity was dependent on the excitation laser power (data not shown), suggesting that this Raman band is derived from the photo-dissociated species. Because the 5-coordinate (5c) heme-CO species has been observed at 521-524 cm Ϫ1 (41,42) and it is sometimes hardly photo-dissociated (43), we assigned this band to the photodissociated 5c-CO species. The Asn and Arg mutants also showed Fe-C at 496 cm Ϫ1 , whereas the Val mutant showed a slight downshift in Fe-C .…”

Section: Resultsmentioning

confidence: 99%

Unique Peroxidase Reaction Mechanism in Prostaglandin Endoperoxide H Synthase-2

Ichimura

Uchida

Taniguchi

et al. 2007

Journal of Biological Chemistry

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Prostaglandin-endoperoxide H synthase-2 (PGHS-2) shows peroxidase activity to promote the cyclooxygenase reaction for prostaglandin H 2 , but one of the highly conserved amino acid residues in peroxidases, distal Arg, stabilizing the developing negative charge on the peroxide through a hydrogen-bonding interaction, is replaced with a neutral amino acid residue, Gln. To characterize the peroxidase reaction in PGHS-2, we prepared three distal glutamine (Gln-189) mutants, Arg (Gln3 Arg), Asn (Gln3 Asn), and Val (Gln3 Val) mutants, and examined their peroxidase activity together with their structural characterization by absorption and resonance Raman spectra. Although a previous study (Landino, L. M., Crews, B. C., Gierse, J. K., Hauser, S. D., and Marnett, L. (1997) J. Biol. Chem. 272, 21565-21574) suggested that the Gln residue might serve as a functionally equivalent residue to Arg, our current results clearly showed that the peroxidase activity of the Val and Asn mutants was comparable with that of the wild-type enzyme. In addition, the Fe-C and C-O stretching modes in the CO adduct were almost unperturbed by the mutation, implying that Gln-189 might not directly interact with the heme-ligated peroxide. Rather, the peroxidase activity of the Arg mutant was depressed, concomitant with the heme environmental change from a sixcoordinate to a five-coordinate structure. Introduction of the bulky amino acid residue, Arg, would interfere with the ligation of a water molecule to the heme iron, suggesting that the side chain volume, and not the amide group, at position 189 is essential for the peroxidase activity of PGHS-2. Thus, we can conclude that the O-O bond cleavage in PGHS-2 is promoted without interactions with charged side chains at the peroxide binding site, which is significantly different from that in typical plant peroxidases.Prostaglandin endoperoxide H synthase (PGHS, 3 also known as cyclooxygenase or COX) is a membrane-bound heme-containing protein catalyzing the first committed step in prostanoid biosynthesis (1-3) including two sequential enzymatic reactions, bis-oxygenation of arachidonic acid to prostaglandin G 2 (PGG 2 ) (cyclooxygenase reaction) and the reduction of PGG 2 to prostaglandin H 2 (PGH 2 ) (peroxidase reaction). PGH 2 is, then, further metabolized to various kinds of prostaglandins, prostacyclins, and thromboxanes by the appropriate synthase (2). Two isoforms of PGHS have been discovered thus far, PGHS-1 and PGHS-2, both of which are composed of ϳ600 amino acid residues, sharing more than 60% sequence identity (4, 5), and their crystal structures are essentially superimposable (6 -8).Although both the PGHS isozymes function as a homodimer of ϳ70-kDa subunits and have similar catalytic properties, they have distinctly different biological functions. PGHS-1 is a "housekeeping" enzyme, expressed constitutively in most tissues, and produces prostaglandins to regulate cellular responses to hormonal stimulation and to regulate vascular homeostasis. PGHS-2, in contrast, is inducibly expressed i...

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Resonance Raman study on synergistic activation of soluble guanylate cyclase by imidazole, YC-1 and GTP

Cited by 20 publications

References 34 publications

Interactions of soluble guanylate cyclase with diatomics as probed by resonance Raman spectroscopy

Interactions of soluble guanylate cyclase with diatomics as probed by resonance Raman spectroscopy

Determinants of the Heme–CO Vibrational Modes in the H-NOX Family

Unique Peroxidase Reaction Mechanism in Prostaglandin Endoperoxide H Synthase-2

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