TY - JOUR

T1 - Sequential Proton Loss Electron Transfer in Deactivation of Iron(IV) Binding Protein by Tyrosine Based Food Components

AU - Tang, Ning

AU - Skibsted, Leif Horsfelt

PY - 2017

Y1 - 2017

N2 - The iron(IV) binding protein ferrylmyoglobin, MbFe(IV)=O, was found to be reduced by tyrosine based food components in aqueous solution through a sequential proton loss electron transfer reaction mechanism without binding to the protein as confirmed by isothermal titration calorimetry. Dopamine and epinephrine are the most efficient food components reducing ferrylmyoglobin to oxymyoglobin, MbFe(II)O2, and metmyoglobin, MbFe(III), as revealed by multivariate curve resolution alternating least-squares with second order rate constants of 33.6 ± 2.3 L/mol/s (ΔH† of 19 ± 5 kJ/mol, ΔS† of -136 ± 18 J/mol K) and 228.9 ± 13.3 L/mol/s (ΔH† of 110 ± 7 kJ/mol, ΔS† of 131 ± 25 J/mol K), respectively, at pH 7.4 and 25 °C. The other tyrosine based food components were found to reduce ferrylmyoglobin to metmyoglobin with similar reduction rates at pH 7.4 and 25 °C. These reduction reactions were enhanced by protonation of ferrylmyoglobin and facilitated proton transfer at acidic conditions. Enthalpy-entropy compensation effects were observed for the activation parameters (ΔH† and ΔS†), indicating the common reaction mechanism. Moreover, principal component analysis combined with heat map were performed to understand the relationship between density functional theory calculated molecular descriptors and kinetic data, which was further modeled by partial least squares for quantitative structure-activity relationship analysis. In addition, a three tyrosine residue containing protein, lysozyme, was also found to be able to reduce ferrylmyoglobin with a second order rate constant of 66 ± 28 L/mol/s as determined by a competitive kinetic method.

AB - The iron(IV) binding protein ferrylmyoglobin, MbFe(IV)=O, was found to be reduced by tyrosine based food components in aqueous solution through a sequential proton loss electron transfer reaction mechanism without binding to the protein as confirmed by isothermal titration calorimetry. Dopamine and epinephrine are the most efficient food components reducing ferrylmyoglobin to oxymyoglobin, MbFe(II)O2, and metmyoglobin, MbFe(III), as revealed by multivariate curve resolution alternating least-squares with second order rate constants of 33.6 ± 2.3 L/mol/s (ΔH† of 19 ± 5 kJ/mol, ΔS† of -136 ± 18 J/mol K) and 228.9 ± 13.3 L/mol/s (ΔH† of 110 ± 7 kJ/mol, ΔS† of 131 ± 25 J/mol K), respectively, at pH 7.4 and 25 °C. The other tyrosine based food components were found to reduce ferrylmyoglobin to metmyoglobin with similar reduction rates at pH 7.4 and 25 °C. These reduction reactions were enhanced by protonation of ferrylmyoglobin and facilitated proton transfer at acidic conditions. Enthalpy-entropy compensation effects were observed for the activation parameters (ΔH† and ΔS†), indicating the common reaction mechanism. Moreover, principal component analysis combined with heat map were performed to understand the relationship between density functional theory calculated molecular descriptors and kinetic data, which was further modeled by partial least squares for quantitative structure-activity relationship analysis. In addition, a three tyrosine residue containing protein, lysozyme, was also found to be able to reduce ferrylmyoglobin with a second order rate constant of 66 ± 28 L/mol/s as determined by a competitive kinetic method.

KW - density functional theory

KW - ferrylmyoglobin

KW - quantitative structure-activity relationship

KW - sequential proton loss electron transfer

KW - tyrosine

U2 - 10.1021/acs.jafc.7b02420

DO - 10.1021/acs.jafc.7b02420

M3 - Journal article

C2 - 28681604

AN - SCOPUS:85026870969

VL - 65

SP - 6195

EP - 6210

JO - Journal of Agricultural and Food Chemistry

JF - Journal of Agricultural and Food Chemistry

SN - 0021-8561

IS - 30

ER -