Reduction of Ferrylmyoglobin by Theanine and Green Tea Catechins. Importance of Specific Acid Catalysis

Jie Yin; Mogens Larsen Andersen; Leif Horsfelt Skibsted

doi:10.1021/jf400219r

Reduction of Ferrylmyoglobin by Theanine and Green Tea Catechins. Importance of Specific Acid Catalysis

Jie Yin, Mogens Larsen Andersen, Leif Horsfelt Skibsted

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9 Citationer (Scopus)

Abstract

Reduction of the hypervalent heme pigment ferrylmyoglobin by green tea catechins in aqueous solution of pH = 7.5 was investigated by stopped-flow spectroscopy. Reduction by the gallic acid esters epigallocatechin gallate (EGCG, k₂ = 1460 L mol^-1 s^-1, 25.0 C, 0.16 ionic strength) and epicatechin gallate (ECG, 1410 L mol^-1 s ^-1) was found faster than for epicatechin (EC, 300 L mol^-1 s^-1) and epigallocatechin (EGC, 200 L mol^-1 s ^-1), even though the gallate ion (G, 330 L mol^-1 s ^-1) is similar in rate to EC. The rate for reduction by EC, EGC, ECG, EGCG, and G shows no correlation with their oxidation potentials or phenolic hydrogen-oxygen bond dissociation energy, but with the pK_a of the most acidic phenol group. Theanine, with an acidity similar to that of EC, reduces ferrylmyoglobin with a similar rate (200 L mol^-1 s ^-1), in support of general acid catalysis with an initial proton transfer prior to electron transfer.

Originalsprog	Engelsk
Tidsskrift	Journal of Agricultural and Food Chemistry
Vol/bind	61
Udgave nummer	12
Sider (fra-til)	3159–3166
Antal sider	8
ISSN	0021-8561
DOI	https://doi.org/10.1021/jf400219r
Status	Udgivet - 27 mar. 2013

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10.1021/jf400219r

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@article{e8749b5898df4d9492a8f9fec6723902,

title = "Reduction of Ferrylmyoglobin by Theanine and Green Tea Catechins. Importance of Specific Acid Catalysis",

abstract = "Reduction of the hypervalent heme pigment ferrylmyoglobin by green tea catechins in aqueous solution of pH = 7.5 was investigated by stopped-flow spectroscopy. Reduction by the gallic acid esters epigallocatechin gallate (EGCG, k2 = 1460 L mol-1 s-1, 25.0 C, 0.16 ionic strength) and epicatechin gallate (ECG, 1410 L mol-1 s -1) was found faster than for epicatechin (EC, 300 L mol-1 s-1) and epigallocatechin (EGC, 200 L mol-1 s -1), even though the gallate ion (G, 330 L mol-1 s -1) is similar in rate to EC. The rate for reduction by EC, EGC, ECG, EGCG, and G shows no correlation with their oxidation potentials or phenolic hydrogen-oxygen bond dissociation energy, but with the pKa of the most acidic phenol group. Theanine, with an acidity similar to that of EC, reduces ferrylmyoglobin with a similar rate (200 L mol-1 s -1), in support of general acid catalysis with an initial proton transfer prior to electron transfer.",

author = "Jie Yin and Andersen, {Mogens Larsen} and Skibsted, {Leif Horsfelt}",

year = "2013",

month = mar,

day = "27",

doi = "10.1021/jf400219r",

language = "English",

volume = "61",

pages = "3159–3166",

journal = "Journal of Agricultural and Food Chemistry",

issn = "0021-8561",

publisher = "American Chemical Society",

number = "12",

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TY - JOUR

T1 - Reduction of Ferrylmyoglobin by Theanine and Green Tea Catechins. Importance of Specific Acid Catalysis

AU - Yin, Jie

AU - Andersen, Mogens Larsen

AU - Skibsted, Leif Horsfelt

PY - 2013/3/27

Y1 - 2013/3/27

N2 - Reduction of the hypervalent heme pigment ferrylmyoglobin by green tea catechins in aqueous solution of pH = 7.5 was investigated by stopped-flow spectroscopy. Reduction by the gallic acid esters epigallocatechin gallate (EGCG, k2 = 1460 L mol-1 s-1, 25.0 C, 0.16 ionic strength) and epicatechin gallate (ECG, 1410 L mol-1 s -1) was found faster than for epicatechin (EC, 300 L mol-1 s-1) and epigallocatechin (EGC, 200 L mol-1 s -1), even though the gallate ion (G, 330 L mol-1 s -1) is similar in rate to EC. The rate for reduction by EC, EGC, ECG, EGCG, and G shows no correlation with their oxidation potentials or phenolic hydrogen-oxygen bond dissociation energy, but with the pKa of the most acidic phenol group. Theanine, with an acidity similar to that of EC, reduces ferrylmyoglobin with a similar rate (200 L mol-1 s -1), in support of general acid catalysis with an initial proton transfer prior to electron transfer.

AB - Reduction of the hypervalent heme pigment ferrylmyoglobin by green tea catechins in aqueous solution of pH = 7.5 was investigated by stopped-flow spectroscopy. Reduction by the gallic acid esters epigallocatechin gallate (EGCG, k2 = 1460 L mol-1 s-1, 25.0 C, 0.16 ionic strength) and epicatechin gallate (ECG, 1410 L mol-1 s -1) was found faster than for epicatechin (EC, 300 L mol-1 s-1) and epigallocatechin (EGC, 200 L mol-1 s -1), even though the gallate ion (G, 330 L mol-1 s -1) is similar in rate to EC. The rate for reduction by EC, EGC, ECG, EGCG, and G shows no correlation with their oxidation potentials or phenolic hydrogen-oxygen bond dissociation energy, but with the pKa of the most acidic phenol group. Theanine, with an acidity similar to that of EC, reduces ferrylmyoglobin with a similar rate (200 L mol-1 s -1), in support of general acid catalysis with an initial proton transfer prior to electron transfer.

U2 - 10.1021/jf400219r

DO - 10.1021/jf400219r

M3 - Journal article

C2 - 23461366

SN - 0021-8561

VL - 61

SP - 3159

EP - 3166

JO - Journal of Agricultural and Food Chemistry

JF - Journal of Agricultural and Food Chemistry

IS - 12

ER -

Reduction of Ferrylmyoglobin by Theanine and Green Tea Catechins. Importance of Specific Acid Catalysis

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