VOLTAMMETRIC DETERMINATION OF ACID DISSOCIATION-CONSTANTS OF PYRROLOQUINOLINE QUINONE AND ITS REDUCED FORM UNDER ACIDIC CONDITIONS

被引：37

作者：

KANO, K ^{[1
]}

MORI, K ^{[1
]}

UNO, B ^{[1
]}

KUBOTA, T ^{[1
]}

IKEDA, T ^{[1
]}

SENDA, M ^{[1
]}

机构：

[1] KYOTO UNIV,FAC AGR,DEPT AGR CHEM,KYOTO 606,JAPAN

来源：

BIOELECTROCHEMISTRY AND BIOENERGETICS | 1990年 / 24卷 / 02期

关键词：

D O I：

10.1016/0302-4598(90)85021-9

中图分类号：

Q5 [生物化学]; Q7 [分子生物学];

学科分类号：

071010 ; 081704 ;

摘要：

The voltammetric properties of the coenzyme pyrroloquinoline quinone (PQQox) have been investigated in the pH range from 0 to 8. PQQox gives a quasi-reversible cyclic voltammogram at a platinum electrode, which is ascribed to a two-electron redox reaction of PQQox to pyrroloquinoline quinol (PQQred). The standard redox potential (Eo′) of the PQQox/PQQred couple has been determined using cyclic voltammetry. From the analysis of the Eo′ vs. pH relationship, the four macroscopic acid dissociation constants (Ka) of both PQQox and PQQred have been determined. The pKas have been assigned to the pyridyl nitrogen and three carboxyl groups. The Eo′ of the PQQox/PQQred couple at pH 7.0 has been determined as -0.175 V vs. SCE (a saturated calomel electrode) with a semiquinone (PQQsem) formation constant of 0.02, where PQQox, PQQred, and PQQsem are present as trianions with the three carboxylate anion substituents. The pH dependence of the absorption spectra of PQQox, has been interpreted in terms of the pKa values. © 1990.

引用

页码：193 / 201

页数：9