| Autor: |
Damiano VB; UNESP - State University of São Paulo, Biochemistry and Applied Microbiology Laboratory, Rua Cristóvão Colombo n 2265, 15054-000, São José do Rio Preto, SP, Brazil., Ward R, Gomes E, Alves-Prado HF, Da Silva R |
| Jazyk: |
angličtina |
| Zdroj: |
Applied biochemistry and biotechnology [Appl Biochem Biotechnol] 2006 Spring; Vol. 129-132, pp. 289-302. |
| DOI: |
10.1385/abab:129:1:289 |
| Abstrakt: |
The alkalophilic bacteria Bacillus licheniformis 77-2 produces significant quantities of thermostable cellulase-free xylanases. The crude xylanase was purified to apparent homogeneity by gel filtration (G-75) and ionic exchange chromatography (carboxymethyl sephadex, Q sepharose, and Mono Q), resulting in the isolation of two xylanases. The molecular masses of the enzymes were estimated to be 17 kDa (X-I) and 40 kDa (X-II), as determined by SDS-PAGE. The Km and V(max) values were 1.8 mg/mL and 7.05 U/mg protein (X-I), and 1.05 mg/mL and 9.1 U/mg protein (X-II). The xylanases demonstrated optimum activity at pH 7.0 and 8.0-10.0 for xylanase X-I and X-II, respectively, and, retained more than 75% of hydrolytic activity up to pH 11.0. The purified enzymes were most active at 70 and 75 degrees C for X-I and X-II, respectively, and, retained more than 90% of hydrolytic activity after 1 h of heating at 50 degrees C and 60 degrees C for X-I and X-II, respectively. The predominant products of xylan hydrolysates indicated that these enzymes were endoxylanases. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
|
Full text from SpringerLink