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EFFECT OF TEMPERATURE ON TWO ENZYMES FROM A PSYCHROPHILIC CHLOROMONAS (CHLOROPHYTA) 1
Author(s) -
Loppes Roland,
Devos Nathalie,
Willem Sabine,
Barthélemy Pascal,
Matagne René F.
Publication year - 1996
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1111/j.0022-3646.1996.00276.x
Subject(s) - psychrophile , biology , extremophile , mesophile , nitrate reductase , chlamydomonas reinhardtii , enzyme , chlorophyta , botany , pectate lyase , biochemistry , thermophile , algae , bacteria , pectinase , genetics , mutant , gene
A psychrophilic green alga belonging to the Chloromonas genus and here named ANT1 was collected in Antarctica. The activities of two enzymes, nitrate reductase and argininosuccinate lyase, were measured at various temperatures and compared to the corresponding enzyme activities in the mesophilic species Chlamydomonas reinhardtii Dangeard. For both enzymes, the temperature for apparent optimal activity was about 20°C lower in ANT1 than in C. reinhardtii. The enzymes were also submitted to various heat treatments before measuring their activities. Both psychrophilic enzymes were more sensitive to heat than the corresponding mesophilic enzymes. It is worth stressing, however, that in both species nitrate reductase was much more sensitive to heat than argininosuccinate lyase, which probably indicates that the peculiar structure of each protein primarily determines its dependence to temperature. Secondary adaptations to low temperatures should then occur to confer the psychrophilic character.