Stability and identification of active-site residues of carboxymethylcellulases from Aspergillus niger and Cellulomonas biazotea
Jazyk angličtina Země Spojené státy americké Médium print
Typ dokumentu časopisecké články, Research Support, U.S. Gov't, Non-P.H.S.
PubMed
9449777
DOI
10.1007/bf02816941
Knihovny.cz E-zdroje
- MeSH
- Actinomycetales enzymologie MeSH
- Aspergillus niger enzymologie MeSH
- bakteriální proteiny chemie izolace a purifikace MeSH
- celulasa * MeSH
- denaturace proteinů MeSH
- fungální proteiny chemie izolace a purifikace MeSH
- glykosidhydrolasy chemie izolace a purifikace MeSH
- izoenzymy chemie izolace a purifikace MeSH
- kinetika MeSH
- koncentrace vodíkových iontů MeSH
- močovina farmakologie MeSH
- rozpouštědla farmakologie MeSH
- teplota MeSH
- vazebná místa MeSH
- vztahy mezi strukturou a aktivitou MeSH
- Publikační typ
- časopisecké články MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
- Názvy látek
- bakteriální proteiny MeSH
- carboxymethylcellulase MeSH Prohlížeč
- celulasa * MeSH
- fungální proteiny MeSH
- glykosidhydrolasy MeSH
- izoenzymy MeSH
- močovina MeSH
- rozpouštědla MeSH
Determination of the apparent pKa's of purified carboxymethylcellulases from Aspergillus niger and Cellulomonas biazotea at different temperatures and in the presence of dioxane indicated two side chain carboxyl groups which controlled the limiting rate in both organisms. The thermostability of both enzymes slightly decreased with increasing pH from 5 to 75 but was unaffected in the presence of 0.5 mmol/L Mn2+. The CMCase from C. biazotea had an activation energy of 35 kJ/mol and a half-life of 89 min in the presence of 8 mol/L urea at 40 degrees C. The half-life of CMCase from A. niger in 8 mol/L urea and at 37 degrees C was 125 min as determined by a 0-9 mol/L transverse urea gradient PAGE. The CMCases from A. niger and C. biazotea had the same thermostabilities in the absence of CMC although the enzyme from the former was more thermostable in the presence of the substrate. The CMCase from A. niger was also more efficient in hydrolyzing CMC than the enzyme from C. biazotea.
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