| Autor: |
Zorn, Holger, Langhoff, Sabine, Scheibner, Manuela, Nimtz, Manfred, Berger, Ralf G. |
| Předmět: |
|
| Zdroj: |
Biological Chemistry; Jul2003, Vol. 384 Issue 7, p1049-1056, 8p, 2 Diagrams, 1 Chart, 4 Graphs |
| Abstrakt: |
Extracellular liquid of the edible fungus Lepista irina was found to effectively degrade β,β-carotene. β-Ionone, β-cyclocitral, dihydroactinidiolide, and 2-hydroxy-2,6,6-trimethylcyclohexanone were formed as volatile breakdown products of β,β-carotene with mycelium-free culture supernatants, whereas β-apo-10'-carotenal was identified as non-volatile degradation product. The key enzyme catalyzing the oxidative cleavage of β,β-carotene was purified with an overall yield of 63% and a purification factor of 43. Biochemical characterization showed a molecular mass of 50.5 κDa and an isoelectric point of 3.75. Fastest β,β-carotene degradation occurred at 34°C and pH values between 3.5 and 4. Degenerate oligonucleotides were derived from N-terminal and internal amino acid sequences. By means of PCR-based cDNA-library screening a 1284 bp cDNA was identified which showed great overall similarity to Pleurotus eryngii polyvalent peroxidases. The obtained sequence contains an open reading frame of 1083 nucleotides, encoding a polypeptide of 361 amino acids. A 30 amino acid signal peptide was identified upstream of the N-terminal sequence of the mature enzyme. The L. irina versatile peroxidase represents the first microbial enzyme capable of carotenoid degradation that has been characterized on a molecular level, proving the participation of extracellular enzymes of white rot fungi in biotic carotenoid degradation processes. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
|
