title: Limited proteolysis of myoglobin opens channel in ferrochelatase-globin complex for iron to zinc transmetallation.
abstract: Recombinant ferrochelatase (BsFECH) from Bacillus subtilis expressed in Escherichia coli BL21(DE3) was found by UV-visible spectroscopy to bind the model substrate tetraphenylporphyrin-sulfonate, TPPS, with Ka=3.8 10(5)mol/L in aqueous phosphate buffer pH 5.7 at 30°C, and to interact with metmyoglobin with Ka=1.07±0.13 10(5)mol/L at 30°C. The iron/zinc exchange in myoglobin occurring during maturation of Parma hams seems to depend on such substrate binding to BsFECH and was facilitated by limited pepsin proteolysis of myoglobin to open a reaction channel for metal exchange still with BsFECH associated to globin. BsFECH increased rate of zinc insertion in TPPS significantly and showed saturation kinetics with an apparent binding constant of Zn(II) to the [enzyme-TPPS] complex of 1.3 10(4)mol/L and a first-order rate constant of 6.6 10(-1)s(-1) for dissociation of the tertiary complex, a similar pattern was found for zinc/iron transmetallation in myoglobin.
authors.affiliation: Instituto de Química de São Carlos, Universidade de São Paulo, Avenida Trabalhador São Carlense 400, CP 780, 13560-470 São Carlos, Brazil.
authors.forename: Marcella O
authors.initials: MO
authors.lastname: Paganelli
authors.affiliation: Food Chemistry, Department of Food Science, University of Copenhagen, Rolighedsvej 30, DK-1958 Frederiksberg C, Denmark.
authors.forename: Alberto B
authors.initials: AB
authors.lastname: Grossi
authors.affiliation: Instituto de Química de São Carlos, Universidade de São Paulo, Avenida Trabalhador São Carlense 400, CP 780, 13560-470 São Carlos, Brazil.
authors.forename: Paulo R
authors.initials: PR
authors.lastname: Dores-Silva
authors.affiliation: Instituto de Química de São Carlos, Universidade de São Paulo, Avenida Trabalhador São Carlense 400, CP 780, 13560-470 São Carlos, Brazil.
authors.forename: Julio C
authors.initials: JC
authors.lastname: Borges
authors.affiliation: Instituto de Química de São Carlos, Universidade de São Paulo, Avenida Trabalhador São Carlense 400, CP 780, 13560-470 São Carlos, Brazil. Electronic address: drcardoso@iqsc.usp.br.
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Cardoso
authors.affiliation: Food Chemistry, Department of Food Science, University of Copenhagen, Rolighedsvej 30, DK-1958 Frederiksberg C, Denmark. Electronic address: ls@food.ku.dk.
authors.forename: Leif H
authors.initials: LH
authors.lastname: Skibsted
mesh_terms: D005294:Ferrochelatase / Q000378:metabolism*; D005914:Globins / Q000378:metabolism*; D007501:Iron / Q000737:chemistry*; D007700:Kinetics; D008786:Metmyoglobin / Q000378:metabolism; D009211:Myoglobin / Q000737:chemistry / Q000378:metabolism*; D011166:Porphyrins / Q000378:metabolism; D059748:Proteolysis; D011994:Recombinant Proteins / Q000378:metabolism; D015032:Zinc / Q000737:chemistry*
chemical_list: D009211:Myoglobin; D011166:Porphyrins; D011994:Recombinant Proteins; D008786:Metmyoglobin; C016136:tetraphenylporphine sulfonate; D005914:Globins; D007501:Iron; D005294:Ferrochelatase; D015032:Zinc
keywords: Ferrochelatase; Meat pigment; Myoglobin; Parma ham; Transmetallation