Enzymatic characterization of the recombinant beta-xylosidase Xynb2
Dr. Liliana Kurz
Center for Environmental, Biological and Chemical Research Facultad de Ciencias y Tecnología, Universidad de Carabobo Valencia, Venezuela.

Abstract — Enzyme research on thermophilic microorganisms has steadily increased given their high catalytic capabilities in extreme conditions, ideal for biotechnological and industrial processes. XynB2, a β-xylosidase from Geobacillus stearothermophilus, and to date the only enzyme of this type displaying transglycosidase activity, offers attractive catalytic applications. Though previously biophysically and biochemically characterized, no detailed kinetics studies on the hydrolysis of various aryl-β-D-xyloside substrates have been reported. The goal of this study was to characterize recombinant XynB2 under maximal activity conditions (pH and temperature). The thermal stability of XynB2 was evaluated to be 69.0 ± 0.6 °C, with a t1/2 of 116 ± 10 min, corresponding to a first order reaction. These and other results obtained from this study may be useful for the application of XynB2 in different fields, including enzyme immobilization, in order to perform catalysis over other type of substrates, like those coming from wastewater, sewage, or industrial residues rich in xylans and/or cellulose.
Keywords — aryl-β-D-xylosides, enzyme catalysis, kinetic parameters, xylanase.

Multiple detection of thermophilic exoenzymes by transfer zymography
Prof. Jeff Wilkesman
Center for Environmental, Biological and Chemical Research Facultad de Ciencias y Tecnología Universidad de Carabobo, Valencia, Venezuela.

Abstract — Analysis of lipases and proteases present in cell-free fractions of thermophilic Bacillus sp. cultures were performed in an enhanced sequential zymography method. After the PAGE run, the gel was electrotransferred to another polyacrylamide gel containing a mixture of glycerol tributyrate, olive oil and gelatin. After transference, this substrate-mix gel was incubated for lipase detection, until bands appeared, and later stained with CBB for protease detection. Assets are, besides detecting two enzymes on a single gel, time and material saving.
Keywords — lipase, protease, sequential zymography, thermophiles.

Listeners are cordially invited!
Chiara Cabrele, Department of Molecular Biology, University of Salzburg

Sponsor: Etta-Becker-Donner Scholarship