Photochemical effects associated with the copper absorption bands of the native hemocyanin from <i>Octopus vulgaris</i>

Tallandini, Laura; Salvato, Benedetto

doi:10.1016/0014-5793(75)80093-7

Cited by 16 publications

(3 citation statements)

References 8 publications

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“…This result is in good agreement with evidence obtained from acid-base titrations of molluscan and arthropod hemocyanins which showed the existence of histidines in the active site of hemocyanin (Salvato et al, 1974;Engelborghs et al, 1976). Photooxidation experiments with light irradiation at the absorption band in the near ultraviolet also point to histidine residues in the active site (Wood and Bannister, 1968;Tallandini et al, 1975).…”

Section: Discussionsupporting

confidence: 89%

Nitrite and nitric oxide treatment of Helix pomatia hemocyanin: single and double oxidation of the active site

Vanderdeen¹,

Hoving²

1977

Biochemistry

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The reaction of nitrite and nitric oxide with Helix pomatia hemocyanin has been studied. One or both of the two copper ions in the active site can be oxidized, depending upon reaction conditions. The single oxidation of the oxygen binding site can be reversed by reduction with hydroxylamine, and the oxygen binding properties of the protein are simultaneously restored. The experiments, including electron paramagnetic resonance, indicate that nitric oxide is not a ligand of copper in the singly oxidized active site and that the oxidized copper ions is coupled to at least two nitrogen atoms of amino acid residues. The doubly oxidized protein can be reduced to a singly oxidized one with ascorbic acid or hydroxylamine; the latter reagent is again able to reduce the singly oxidized state and to restore the oxygen binding properties.

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Section: Discussionsupporting

confidence: 89%

Nitrite and nitric oxide treatment of Helix pomatia hemocyanin: single and double oxidation of the active site

Vanderdeen¹,

Hoving²

1977

Biochemistry

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“…The UV resonance Raman spectrum of oxyHc is most straightforwardly interpreted in terms of three imidazole ligands;1 this number also accords with the imidazole photooxidation stoichiometry. [16][17] Consequently, we think it likely that the coordination number is five for oxyHc (three imidazoles, O2, and the putative extra bridging ligand) and three for deoxyHc, the three imidazoles presumably remaining bound to Cu(I). The oxyHc resonance Raman spectra suggest that one of the copperimidazole bonds has a lowered stretching frequency, and presumably a slightly larger bond distance, than the other two.…”

Section: Discussionmentioning

confidence: 99%

Structural studies of the hemocyanin active site. 1. Extended x-ray absorption fine structure (EXAFS) analysis

Brown¹,

Powers²,

Kincaid³

et al. 1980

J. Am. Chem. Soc.

191

105

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“…In contrast to the rapidly increasing information on the involvement of the metal in the binding and activation of oxygen in these copper proteins (Eickman et al, 1979;Brown et al, 1980; Himmelwright et al, 1980), the knowledge of the part played by the protein moiety especially with regard to the metal ligands and the active-site residues is still limited. Although a number of investigations implicate the involvement of histidyl residues as metal ligands of the active-site copper (Salvato et al, 1974;Tallandini et al, 1975;Engelborghs & Lontie, 1973;Gutteridge et al, 1977) , progress has been hampered by the complexity and molecular heterogeneity of these molecules. In this report, the residues of the active-site region of Neurospora tyrosinase were identified by chemical modification employing dye-sensitized photooxidation.…”

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confidence: 99%

Histidine at the active site of Neurospora tyrosinase

Pfiffner¹,

Lerch²

1981

Biochemistry

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The involvement of histidyl residues as potential ligands to the binuclear active-site copper of Neurospora tyrosinase was explored by dye-sensitized photooxidation. The enzymatic activity of the holoenzyme was shown to be unaffected by exposure to light in the presence of methylene blue; however, irradiation of the apoenzyme under the same conditions led to a progressive loss of its ability to be reactivated with Cu2+. This photoinactivation was paralleled by a decrease in the histidine content whereas the number of histidyl residues in the holoenzyme remained constant. Copper measurements of photooxidized, reconstituted apoenzyme demonstrated the loss of binding of one copper atom per mole of enzyme as a consequence of photosensitized oxidation of three out of nine histidine residues. Their sequence positions were determined by a comparison of the relative yields of the histidine containing peptides of photooxidized holo- and apotyrosinases. The data obtained show the preferential modification of histidyl residues 188, 193, and 289 and suggest that they constitute metal ligands to one of the two active-site copper atoms. Substitution of copper by cobalt was found to afford complete protection of the histidyl residues from being modified by dye-sensitized photooxidation.

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Photochemical effects associated with the copper absorption bands of the native hemocyanin from Octopus vulgaris

Cited by 16 publications

References 8 publications

Nitrite and nitric oxide treatment of Helix pomatia hemocyanin: single and double oxidation of the active site

Nitrite and nitric oxide treatment of Helix pomatia hemocyanin: single and double oxidation of the active site

Structural studies of the hemocyanin active site. 1. Extended x-ray absorption fine structure (EXAFS) analysis

Histidine at the active site of Neurospora tyrosinase

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