title: Direct evidence of the metal-free nature of sirohydrochlorin in desulfoviridin.
abstract: We have obtained direct evidence that the majority of the sirohydrochlorin chromophore in the dissimilatory sulfite reductase desulfoviridin from Desulfovibrio gigas, is not associated with any metal. The evidence comes from resonance Raman measurements of native and deuterated samples of desulfoviridin. The breathing mode v4 (or v4*) at 1336 cm-1 in the native enzyme is downshifted to 1326 cm-1 upon deuteration. This mode is not sensitive to deuteration if a metal is present at the center of the chromophore inside protein or in solution. The results also establish the existence of exchangeable core hydrogen(s) at the pyrrolic nitrogen(s).
authors.affiliation: Department of Physics, Emory University, Atlanta, GA 30322.
authors.forename: K K
authors.initials: KK
authors.lastname: Lai
authors.forename: I
authors.initials: I
authors.lastname: Moura
authors.forename: M Y
authors.initials: MY
authors.lastname: Liu
authors.forename: J
authors.initials: J
authors.lastname: LeGall
authors.forename: K T
authors.initials: KT
authors.lastname: Yue
mesh_terms: D003901:Desulfovibrio / Q000737:chemistry; D008670:Metals / Q000737:chemistry; D050862:Oxidoreductases Acting on Sulfur Group Donors / Q000737:chemistry*; D013059:Spectrum Analysis, Raman; D014578:Uroporphyrins / Q000737:chemistry*
chemical_list: D008670:Metals; D014578:Uroporphyrins; C014188:sirohydrochlorin; D050862:Oxidoreductases Acting on Sulfur Group Donors