Browsing by Author "Tello, M"

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    Characterization of three new manganese peroxidase genes from the ligninolytic basidiomycete Ceriporiopsis subvermispora
    (2000) Tello, M; Corsini, G; Larrondo, LF; Salas, L; Lobos, S; Vicuña, R
    Three new genes (Cs-mnp2A, Cs-mnp2B and Cs-mnp3) coding for manganese-dependent peroxidase (MnP) have been identified in the white-rot basidiomycete Ceriporiopsis subvermispora. The mature proteins contain 366 (MnP2A and MnP2B) and 364 (MnP3) amino acids, which are preceded by leader sequences of 21 and 24 amino acids, respectively. Cs-mnp2A and Cs-mnp2B appear to be alleles, since the corresponding protein sequences differ in only five residues, The upstream region of Cs-mnp2B contains a TATA box, AP-1 and AP-2 sites, as well as sites for transcription regulation by metals (two), cAMP (two) and xenobiotics (one). Some of these elements are also found in the regulatory region of Cs-MnP3, Transcription of Cs-mnp2A and Cs-mnp2B, but not that of Cs-mnp3, is activated by manganese. (C) 2000 Elsevier Science B.V. All rights reserved.
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    Enzymology and molecular genetics of the ligninolytic system of the basidiomycete Ceriporiopsis subvermispora
    (2001) Lobos, S; Tello, M; Polanco, R; Larrondo, LF; Manubens, A; Salas, L; Vicuña, R
    Lignin, the most abundant renewable source of aromatic carbon on earth, consists in a highly irregular three-dimensional biopolymer of oxygenated phenylpropanoid units. In natural environments, lignin is only degraded efficiently by some fungi belonging to the group of basidiomycetes. These microorganisms secrete an array of oxidases and peroxidases for this purpose, which may be produced in various combinations. This article summarizes our studies on a particular strain called Ceriporiopsis subvermispora, a fungus which is highly agressive towards lignin when growing on wood.
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    Isolation and characterization of homokaryotic strains from the ligninolytic basidiomycete Ceriporiopsis subvermispora
    (2001) Tello, M; Seelenfreund, D; Lobos, S; Gaskell, J; Cullen, D; Vicuña, R
    Genetic analyses of the lignin-degrading fungus Ceriporiopsis subvermispora is complicated by a dikaryotic nuclear condition and the absence of sport: forms. Previous investigations had identified a family of closely related sequences encoding manganese peroxidase (MnP), but the relationship between genes and allelic variants could not be experimentally established. Addressing this issue, homokaryotic derivatives of C. subvermipora strain FP105752 were isolated from regenerated protoplasts. Designated CsA and CsB. their homokaryotic nature was established by polymerase chain reaction amplification and sequence analysis of the allelic variants of three MnP genes. Isoelectrofocusing revealed fewer MnP isoenzymes in filtrates of homokaryon cultures relative to the parental strain. The homokaryotic strains will simplify genetic analyses, particularly the identification of neu genes. (C) 2001 Federation of European Microbiological Societies. published by Elsevier Science B.V. All rights reserved.
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    Synthesis of gizzerosine, a toxic substance found in fish meal
    (1999) Herrera, C; Tello, M; Ibañez, I; Valenzuela, O; Olivares, L
    A simple methodology was used for the synthesis of racemic gizzerosine, whose S-enantiomer has been considered as the main responsible substance for producing the black vomit syndrome in birds. This work has been carried out using classical reactions of the traditional organic chemistry, based on the Gabriel synthesis for the preparation of synthetic amino acids. With the use of easily available materials and reactants, this substance was obtained in reasonable yields and at a lower cost, than that reported previously by others. The intermediaries were analyzed using physical and spectroscopic techniques. The synthetic gizzerosine, obtained in the present work, was confirmed as the expected product, corroborating the structure, by means of the proton nuclear magnetic resonance spectra. The results of the analyses were consistent with the data reported previously in literature, respect to the physical and chemical characterization of the final product of the described synthesis pathway.