- Title
- Carbonic anhydrase activity of dinuclear CuII complexes with patellamide model ligands
- Creator
- Comba, Peter; Gahan, Lawrence R.; Hanson, Graeme R.; Maeder, Marcel; Westphal, Michael
- Relation
- Dalton Transactions Vol. 43, Issue 8, p. 3144-3152
- Publisher Link
- http://dx.doi.org/10.1039/c3dt53135j
- Publisher
- Royal Society of Chemistry
- Resource Type
- journal article
- Date
- 2014
- Description
- The dicopper(II) complexes of six pseudo-octapeptides, synthetic analogues of ascidiacyclamide and the patellamides, found in ascidians of the Pacific and Indian Oceans, are shown to be efficient carbonic anhydrase model complexes with kcat up to 7.3 × 10³ s⁻¹ (uncatalyzed: 3.7 × 10⁻² s⁻¹; enzyme-catalyzed: 2 × 105–1.4 × 106 s⁻¹) and a turnover number (TON) of at least 1700, limited only by the experimental conditions used. So far, no copper-based natural carbonic anhydrases are known, no faster model systems have been described and the biological role of the patellamide macrocycles is so far unknown. The observed CO₂ hydration rates depend on the configuration of the isopropyl side chains of the pseudo-octapeptide scaffold, and the naturally observed R*,S*,R*,S* geometry is shown to lead to more efficient catalysts than the S*,S*,S*,S* isomers. The catalytic efficiency also depends on the heterocyclic donor groups of the pseudo-octapeptides. Interestingly, the dicopper(II) complex of the ligand with four imidazole groups is a more efficient catalyst than that of the close analogue of ascidiacyclamide with two thiazole and two oxazoline rings. The experimental observations indicate that the nucleophilic attack of a CuII-coordinated hydroxide at the CO₂ carbon center is rate determining, i.e. formation of the catalyst-CO₂ adduct and release of carbonate/bicarbonate are relatively fast processes.
- Subject
- dicopper(II); Pacific and Indian Oceans; patellamide macrocycles; geometry
- Identifier
- http://hdl.handle.net/1959.13/1305176
- Identifier
- uon:20991
- Identifier
- ISSN:1477-9226
- Language
- eng
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