TY - JOUR A1 - Lumpe, Henning A1 - Mayer, Peter A1 - Daumann, Lena J. T1 - Crystal structure of a calcium(II)–pyrroloquinoline quinone (PQQ) complex outside a protein environment Y1 - 2020-11-05 VL - 76 IS - 12 SP - 1051 EP - 1056 JF - Acta Crystallographica Section C DO - 10.23689/fidgeo-4206 PB - 5 Abbey Square CY - Chester, Cheshire CH1 2HU, England N2 - Pyrroloquinoline quinone (PQQ) is an important cofactor of calcium‐ and lanthanide‐dependent alcohol dehydrogenases, and has been known for over 30 years. Crystal structures of Ca–MDH enzymes (MDH is methanol dehydrogenase) have been known for some time; however, crystal structures of PQQ with biorelevant metal ions have been lacking in the literature for decades. We report here the first crystal structure analysis of a Ca–PQQ complex outside the protein environment, namely, poly[[undecaaquabis(μ‐4,5‐dioxo‐4,5‐dihydro‐1H‐pyrrolo[2,3‐f]quinoline‐2,7,9‐tricarboxylato)tricalcium(II)] dihydrate], {[Ca3(C14H3N2O8)2(H2O)11]·2H2O}n. The complex crystallized as Ca3PQQ2·13H2O with Ca2+ in three different positions and PQQ3−, including an extensive hydrogen‐bond network. Similarities and differences to the recently reported structure with biorelevant europium (Eu2PQQ2) are discussed. N2 - Pyrroloquinoline quinone (PQQ) is an important cofactor of calcium‐ and lanthanide‐dependent alcohol dehydrogenases. The crystal structure of a Ca–PQQ complex (Ca3PQQ2·13H2O) is reported for the first time outside a protein environment. image UR - http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/8546 ER -