Absence of synproportionation between oxy and ferryl leghemoglobin. off

TY - JOUR

T1 - Absence of synproportionation between oxy and ferryl leghemoglobin. off

AU - Mathieu, C

AU - Swaraj, K

AU - Davies, Michael Jonathan

AU - Trinchant, J C

AU - Puppo, A

PY - 1997/8

Y1 - 1997/8

N2 - The synproportionation reaction between ferryl leghemoglobin and oxyleghemoglobin does not occur, at least under conditions where this process could be clearly demonstrated with myoglobin and hemoglobin. In contrast, a cross synproportionation can occur between oxyleghemoglobin and ferryl myoglobin or between ferryl leghemoglobin and oxymyoglobin. The non-exposure, at the surface of the leghemoglobin molecule, of the nearest tyrosine residue to the heme group could explain this behaviour. Thus leghemoglobin per se does not appear to be able to act as an antioxidant in removing H2O2 by synproportionation. However, in the presence of ascorbate and/or glutathione which can reduce ferryl leghemoglobin, this hemoprotein could act as an H2O2-removing antioxidant, in a process similar to that described for myoglobin. This could also explain why, despite the absence of synproportionation, ferryl leghemoglobin is not detected in nodule extracts.

AB - The synproportionation reaction between ferryl leghemoglobin and oxyleghemoglobin does not occur, at least under conditions where this process could be clearly demonstrated with myoglobin and hemoglobin. In contrast, a cross synproportionation can occur between oxyleghemoglobin and ferryl myoglobin or between ferryl leghemoglobin and oxymyoglobin. The non-exposure, at the surface of the leghemoglobin molecule, of the nearest tyrosine residue to the heme group could explain this behaviour. Thus leghemoglobin per se does not appear to be able to act as an antioxidant in removing H2O2 by synproportionation. However, in the presence of ascorbate and/or glutathione which can reduce ferryl leghemoglobin, this hemoprotein could act as an H2O2-removing antioxidant, in a process similar to that described for myoglobin. This could also explain why, despite the absence of synproportionation, ferryl leghemoglobin is not detected in nodule extracts.

KW - Antioxidants

KW - Ascorbic Acid

KW - Cyclic N-Oxides

KW - Glutathione

KW - Hydrogen Peroxide

KW - Kinetics

KW - Leghemoglobin

KW - Models, Molecular

KW - NADH, NADPH Oxidoreductases

KW - Protein Conformation

KW - Soybeans

KW - Spectrophotometry

KW - Surface Properties

KW - Tyrosine

M3 - Journal article

C2 - 9350420

SN - 1071-5762

VL - 27

SP - 165

EP - 171

JO - Free Radical Research

JF - Free Radical Research

IS - 2

ER -