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Ambident Behavior of the “New Vitamin” Methoxatin (Cofactor PQQ) towards Metals: Coordinative Stabilization of the Pyrrolide Form and the Semiquinone Form
Author(s) -
Schwederski Brigitte,
Kasack Volker,
Kaim Wolfgang,
Roth Eberhard,
Jordanov Jeanne
Publication year - 1990
Publication title -
angewandte chemie international edition in english
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 0570-0833
DOI - 10.1002/anie.199000781
Subject(s) - deprotonation , semiquinone , chemistry , cofactor , metal , ring (chemistry) , quinone , crystallography , stereochemistry , copper , oxygen , photochemistry , ion , organic chemistry , enzyme
The biochemical function of the o ‐quinonoid “new vitamin” methoxatin (Cofactor PQQ) is coupled with the formation of the semiquinone form and possibly also with metal coordination. In contrast to “hard” copper(II) fragments, the “soft” [Ru(bpy) 2 ] 2⊕ , which is capable of π‐back bonding, coordinates via the two o ‐quinone oxygen atoms of the methoxatin; both the semiquinoid intermediate as well as the form with deprotonated pyrrole ring are thereby stabilized and shifted into a physiologically relevant potential‐ and pH‐range.