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Ein L 3 ZnOH‐Komplex als funktionelles Modell des Enzyms Carboanhydrase
Author(s) -
Alsfasser Ralf,
Ruf Michael,
Vahrenkamp Heinrich
Publication year - 1993
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19931260322
Subject(s) - chemistry , carbonic anhydrase , perchlorate , bicarbonate , stereochemistry , ligand (biochemistry) , medicinal chemistry , hydroxide , zinc , hydrolysis , enzyme , inorganic chemistry , ion , organic chemistry , biochemistry , receptor
An L 3 ZnOH Complex as a Functional Model of the Enzyme Carbonic Anhydrase The tridentate ligand hydrotris(3‐ tert 1‐butyl‐5‐methylpyrazolyl)borate (L 3 ) reacts with zinc perchlorate hexahydrate to form L 3 ZnOH ( 1 ) which is the first mononuclear neutral zinc hydroxide complex. 1 is a structural model of the enzyme carbonic anhydrase due to its tetrahedral coordination with three N‐heterocycles and one OH ion as ligands. Its functional analogy to the enzyme involves (a) reversible uptake of CO 2 forming the unstable bicarbonate complex L 3 ZnOCOOH ( 4 ) in solution from which the dinuclear carbonate complex L 3 ZnOC(O)OZnL 3 ( 3 ) crystallizes, (b) reaction with dialkyl pyrocarbonates forming the complexes L 3 ZnOC(O)OR ( 5 ) which are stable esters of the bicarbonate complex and which are easily hydrolyzed to ROH, CO 2 , and L 3 ZnOH, (c) thermal decarboxylation of the ethyl carbonate complex 5b resulting in the ethanolate complex L 3 ZnOEt ( 6 ) which is extremely sensitive to hydrolysis, (d) “inhibition” by small anions due to conversion of 1 into the complexes L 3 ZnX ( 7 ; XCl, CN, N 3 , OAc). The identity of the various L 3 Zn derivatives is established by NMR methods and structure determinations.