Zhang Z, Tillekeratne L M, Kirchhoff J R, Hudson R A
Department of Medicinal and Biological Chemistry, College of Pharmacy, University of Toledo, OH 43606, USA.
Biochem Biophys Res Commun. 1995 Jul 6;212(1):41-7. doi: 10.1006/bbrc.1995.1933.
Pyrroloquinoline quinone 1 (PQQ, methoxatin, 4,5-dihydro-4,5-dioxo-1H-pyrrolo[2,3-f]quinoline-2,7,9-tricarboxylic acid) is a novel coenzyme. Closely related isomeric analogues of PQQ may be formed in nature and may possess PQQ-like functions. Here, the electrochemical pH-dependent properties and the high performance liquid chromatographic (HPLC) separation protocols are reported for three major isomeric PQQ analogues likely to be formed in nature. The electrochemical data (cyclic voltammetry) provided the pKas of the five ionizable groups in each isomeric PQQ. The HPLC protocols provide the means of investigating the formation of PQQ and the PQQ isomers reported here during the normal turnover of eukaryotic amine oxidases containing integral topaquinone residues, as well as from direct enzyme-mediated reactions which remain to be characterized.
吡咯喹啉醌1（PQQ，甲氧喋呤，4,5-二氢-4,5-二氧代-1H-吡咯并[2,3-f]喹啉-2,7,9-三羧酸）是一种新型辅酶。与PQQ密切相关的同分异构体类似物可能在自然界中形成，并可能具有类似PQQ的功能。本文报道了三种可能在自然界中形成的主要同分异构PQQ类似物的电化学pH依赖性特性和高效液相色谱（HPLC）分离方法。电化学数据（循环伏安法）提供了每种同分异构PQQ中五个可电离基团的pKa值。HPLC方法提供了一种手段，用于研究在含有完整topaquinone残基的真核胺氧化酶的正常周转过程中以及在仍有待表征的直接酶介导反应中PQQ和本文报道的PQQ异构体的形成情况。
