Browsing by Author "Steiner, J"

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    An α-L-arabinofuranosidase from Penicillium purpurogenum
    (2000) De Ioannes, P; Peirano, A; Steiner, J; Eyzaguirre, J
    Penicillium purpurogenum secretes arabinofuranosidase to the growth medium. Highest levels of enzyme (1.0 U ml(-1)) are obtained when L-arabitol is used as carbon source, while 0.85 and 0.7 U ml(-1) are produced with sugar beet pulp and oat spelts xylan, respectively. By means of a zymogram, three bands with arabinofuranosidase activity have been detected in the supernatant of a culture grown in oat spelts xylan. One of the enzymes was purified to homogeneity from this supernatant using gel filtration (BioGel P-100), cation exchange chromatography (CM-Sephadex C-50), hydrophobic interaction chromatography (phenyl agarose) and a second BioGel P-100 column. The enzyme is a monomer of 58 kDa with a pI of 6.5. Optimum pH is 4.0 and optimal temperature 50 degrees C. The arabinofuranosidase is highly specific for alpha-L-arabinofuranosides and liberates arabinose from arabinoxylan. The enzyme shows hyperbolic kinetics towards p-nitrophenyl-alpha-L-arabinofuranoside with a K-M of 1.23 mM. A 36-residue N-terminal sequence is over 70% identical to that of fungal arabinofuranosidases belonging to family 54 of the glycosyl hydrolases. Based on the sequence similarity and other biochemical properties it is proposed that the purified enzyme from P. purpurogenum belongs to family 54. (C) 2000 Elsevier Science B.V. All rights reserved.
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    Cloning, sequencing and expression of the cDNA of endoxylanase B from Penicillium purpurogenum
    (1997) Diaz, R; Sapag, A; Peirano, A; Steiner, J; Eyzaguirre, J
    The cDNA, for xylanase B from Penicillium purpurogenum was cloned and sequenced. This DNA encodes a protein of 208 amino acids which is expected to yield a protein of 183 residues upon processing of the N terminus. The sequence of the predicted protein is very similar to that of 40 other xylanase domains which belong to family G of cellulases/xylanases (73-21% identity).
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    Short communication
    (1998) Steiner, J; Carmona, P; Ponce, C; Berti, M; Eyzaguirre, J
    Penicillium purpurogenum was mutated with u.v. light to increase xylanase production. The best mutant, UV-64, was treated with N-methyl-N'-nitro-N-nitrosoguanidine and a second generation of mutants was obtained (NG-188 and NG-737). NG-737 produced 125 U of xylanase/ml when grown on oat spelts xylan supplemented with wheat bran compared with 69 U/ml for the wild-type strain. The mutants also showed a 2.2-fold increase in beta-xylosidase as compared with the wild-type.