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Titolo:
CHARACTERIZATION OF ACID INVERTASE FROM THE SNOW MOLD MONOGRAPHELLA-NIVALIS - A MESOPHILIC ENZYME FROM A PSYCHROPHILIC FUNGUS
Autore:
CAIRNS AJ; HOWARTH CJ; POLLOCK CJ;
Indirizzi:
INST GRASSLAND & ENVIRONM RES,DEPT CELL BIOL,PLAS GOGERDDAN ABERYSTWYTH SY23 3EB DYFED WALES INST GRASSLAND & ENVIRONM RES,DEPT ENVIRONM BIOL ABERYSTWYTH SY23 3EBDYFED WALES
Titolo Testata:
New phytologist
fascicolo: 3, volume: 130, anno: 1995,
pagine: 391 - 400
SICI:
0028-646X(1995)130:3<391:COAIFT>2.0.ZU;2-#
Fonte:
ISI
Lingua:
ENG
Soggetto:
LOLIUM-TEMULENTUM L; FRUCTOSYL TRANSFERASE-ACTIVITY; PSEUDOMONAS-FLUORESCENS; FRUCTAN BIOSYNTHESIS; EXCISED LEAVES; SCHIZOSACCHAROMYCES-POMBE; EXTRACELLULAR PROTEASES; DENOVO SYNTHESIS; PURIFICATION; METALLOPROTEASE;
Keywords:
CRYOPROTECTANT; COLD-ACTIVE; FRUCTAN; FUSARIUM NIVALE; LOW TEMPERATURE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
44
Recensione:
Indirizzi per estratti:
Citazione:
A.J. Cairns et al., "CHARACTERIZATION OF ACID INVERTASE FROM THE SNOW MOLD MONOGRAPHELLA-NIVALIS - A MESOPHILIC ENZYME FROM A PSYCHROPHILIC FUNGUS", New phytologist, 130(3), 1995, pp. 391-400

Abstract

A soluble acid invertase was extracted by mechanical disruption of mycelium of the psychrophile Monographella nivalis grown on sucrose in submerged culture. The crude preparation was stable to incubation at pH6.2 for 1 h at temperatures up to 47 degrees C and was stable to handling at room temperature. Half of the initial activity was lost after 1 h at 52 degrees C and all activity was lost after 1 h at 57 degrees C. A Single isoform with activity against sucrose was detected on bothnative PAGE and IEF activity gels, exhibiting an isoelectric point ofpH 3.6. The activity bound tightly to Concanavalin A-sepharose and was not displaced by 500 mM alpha-methyl mannopyranosidase indicating the enzyme to be a mannose-containing glycoprotein. By gel filtration, the apparent M(r) was determined at 195 kDa. The invertase was purified106-fold by salt precipitation. The partially purified enzyme exhibited maximal activity at pH 4.2 and apparent Michaelis constants for sucrose of 1.2, 2.0 and 2.6 mM at 3, 9 and 15 degrees C. The activity increased exponentially with temperature in the range 7-55 degrees C. Q(10) fell with increased temperature giving values of 1.96 between 5 and15 degrees C and 1.60 between 40 and 50 degrees C. Maximal activity was recorded at 55 degrees C. Arrhenius analysis of temperature data inthe range 7-52 degrees C produced a continuous linear relationship. The activation energy for sucrose hydrolysis was 38.8 kJ mol(-1). The thermal stability and thermal kinetic properties of the invertase were similar to those of invertases from mesophilic organisms. The invertase catalysed fructosyl transfer at 13% of the molar activity against sucrose when assayed under conditions analogous to those in culture. Themajor fructan products were neokestose, isokestose, kestose and an unidentified tetrasaccharide. Traces of larger fructans were also detected. The transient accumulation of fructan in cultures of M. nivalis can be explained as a side reaction of invertase activity. The enzymological and physiological data do not suggest a cryoprotective function for fructan during the growth of the fungus.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 04/12/20 alle ore 20:08:47