Browsing by Author "Eyzaguirre, J"

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    Acetyl xylan esterase II from Penicillium purpurogenum is similar to an esterase from Trichoderma ressei but lacks a cellulose binding domain
    (1998) Gutiérrez, R; Cederlund, E; Hjelmqvist, L; Peirano, A; Herrera, F; Ghosh, D; Duax, W; Jörnvall, H; Eyzaguirre, J
    Penicillium purpurogenum produces at least two acetyl xylan esterases (AXE I and LI). The AXE II cDNA, genomic DNA and mature protein sequences were determined and show that the axe 2 gene contains two introns, that the primary translation product has a signal peptide of 27 residues, and that the mature protein has 207 residues, The sequence is similar to the catalytic domain of AXE I from Trichoderma reesei (67% residue identity) and putative active site residues are conserved, but the Penicillium enzyme lacks the linker and cellulose binding domain, thus explaining why it does not bind cellulose in contrast to the Tricoderma enzyme. These results point to a possible common ancestor gene for the active site domain, while the linker and the binding domain may have been added to the Trichoderma esterase by gene fusion. (C) 1998 Federation of European Biochemical Societies.
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    Acetyl xylan esterase II from Penicillium purpurogenum is similar to an esterase from Trichoderma ressei but lacks a cellulose binding domain
    (1998) Gutierrez, R; Cederlund, E; Hjelmqvist, L; Peirano, A; Herrera, F; Ghosh, D; Duax, W; Jornvall, H; Eyzaguirre, J
    Penicillium purpurogenum produces at least two acetyl xylan esterases (AXE I and LI). The AXE II cDNA, genomic DNA and mature protein sequences were determined and show that the axe 2 gene contains two introns, that the primary translation product has a signal peptide of 27 residues, and that the mature protein has 207 residues, The sequence is similar to the catalytic domain of AXE I from Trichoderma reesei (67% residue identity) and putative active site residues are conserved, but the Penicillium enzyme lacks the linker and cellulose binding domain, thus explaining why it does not bind cellulose in contrast to the Tricoderma enzyme. These results point to a possible common ancestor gene for the active site domain, while the linker and the binding domain may have been added to the Trichoderma esterase by gene fusion. (C) 1998 Federation of European Biochemical Societies.
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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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    Multiple conformations of catalytic serine and histidine in acetylxylan esterase at 0.90 Å
    (2001) Ghosh, D; Sawicki, M; Lala, P; Erman, M; Pangborn, W; Eyzaguirre, J; Gutiérrez, R; Jörnvall, H; Thiel, DJ
    Acetylxylan esterase (AXEII; 207 amino acids) from Penicillium purpurogenum has substrate specificities toward acetate esters of D-xylopyranose residues in xylan and belongs to a new class of alpha/beta hydrolases. The crystal structure of AXEII has been determined by single isomorphous replacement and anomalous scattering, and refined at 0.90- and 1.10-Angstrom resolutions with data collected at 85 K and 295 K, respectively. The tertiary structure consists of a doubly wound alpha/beta sandwich, having a central six-stranded parallel beta -sheet flanked by two parallel ol-helices on each side. The catalytic residues Ser(90), His(187), and Ap(175) are located at the C-terminal end of the sheet, an exposed region of the molecule. The serine and histidine side chains in the 295 K structure show the frequently observed conformations in which Ser(90) is trans and the hydroxyl group is in the plane of the imidazole ring of His(187), However, the structure at 85 K displays an additional conformation in which Ser(90) side-chain hydroxyl is away from the plane of the imidazole ring of His(187). The His(187) side chain forms a hydrogen bond with a sulfate ion and adopts an altered conformation. The only other known hydrolase that has a similar tertiary structure is Fusarium solani cutinase, The exposed nature of the catalytic triad suggests that AXEII is a pure esterase, i.e. an alpha/beta hydrolase with specificity for nonlipidic polar substrates.