Purification and catalytic properties of two catechol 1,2-dioxygenase isozymes from benzoate-grown cells of Acinetobacter radioresistens |
| |
Authors: | Briganti F Pessione E Giunta C Mazzoli R Scozzafava A |
| |
Institution: | (1) Dipartimento di Chimica, Università degli Studi di Firenze, 50121 Florence, Italy;(2) Dipartimento di Biologia Animale, Università di Torino, 10100 Turin, Italy;(3) Dipartimento di Chimica, Università degli Studi di Firenze, 50121 Florence, Italy |
| |
Abstract: | Two catechol 1,2-dioxygenase (C1,2O) isozymes (IsoA and IsoB) have been purified to homogeneity from a strain of Acinetobacter radioresistens grown on benzoate as the sole carbon and energy source. IsoA and IsoB are both homodimers composed of a single type of subunit with molecular mass of 38,600 and 37,700, Da respectively. In conditions of low ionic strength, IsoA can aggregate as a trimer, in contrast to IsoB, which maintains the dimeric structure, as also supported by the kinetic parameters (Hill numbers). IsoA is identical to the enzyme previously purified from the same bacterium grown on phenol, whereas the IsoB is selectively expressed using benzoate as carbon source. This is the first evidence of the presence of differently expressed C1,2O isozymes in A. radioresistens or more generally of multiple C1,2O isozymes in benzoate-grown Acinetobacter cells. Purified IsoA and IsoB contain approximately 1 iron(III) ion per subunit and both show electronic absorbance and EPR features typical of Fe(III) intradiol dioxygenases. The kinetic properties of the two enzymes such as the specificities toward substituted catechols, the main catalytic parameters, and their behavior in the presence of different kind of inhibitors are, unexpectedly, very similar, in contrast to most of the previously known dioxygenase isozymes. |
| |
Keywords: | Catechol 1 2-dioxygenase intradiol dioxygenase aromatic compound degradation Acinetobacter radioresistens isozymes differential expression |
本文献已被 PubMed SpringerLink 等数据库收录! |
|