title: Biochemical and Electron Microscopic Studies of the Streptomyces reticuli Cellulase (Avicelase) in Its Mycelium-Associated and Extracellular Forms.
abstract: Streptomyces reticuli is able to grow efficiently with crystalline cellulose (Avicel) as the sole carbon source. Cultivation in the presence of the nonionic detergent Tween 80 at a concentration of 0.1% led to a 10-fold increase in extracellular cellulolytic activity. Under these conditions, one single 82-kDa cellulase (Avicelase) capable of degrading crystalline and soluble cellulose as well as cellodextrins and p-nitrophenylcellobioside was purified to apparent homogeneity by a procedure which consisted of two consecutive anion-exchange chromatographies followed by chromatofocusing. Aggregation, which was a major problem during protein purification, could be avoided by including Triton X-100 at a concentration of 0.1% in every chromatographic step. The Avicelase was identified in extracellular and mycelium-associated forms, the latter of which could be released efficiently by nonionic detergents. In addition, a 42-kDa truncated form retaining cellulolytic activity was identified which had been generated from the 82-kDa enzyme by a protease. Antibodies raised against the mycelium-associated Avicelase reacted with the 42-kDa derivative and the extracellular form. The mycelial association of the enzyme was confirmed by immunofluorescence and immunoelectron microscopies.
authors.affiliation: Fachbereich Biologie/Chemie, Universität Osnabrück, D-4500 Osnabrück, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Schlochtermeier
authors.forename: F
authors.initials: F
authors.lastname: Niemeyer
authors.forename: H
authors.initials: H
authors.lastname: Schrempf