title: Temperature optima of enzyme-catalysed reactions in microemulsion systems.
abstract: Ternary phase systems (water/surfactant/organic solvent) were utilised to increase and broaden the temperature optima of enzyme-catalysed reactions. Alcohol dehydrogenases from yeast and Thermoanaerobium brockii (EC 1.1.1.1 and EC 1.1.1.2), lactate dehydrogenase from Lactobacillus delbrueckii (EC 1.1.1.28) and the particulate hydrogenase from Ralstonia eutropha (EC 1.18.99.1) were used as model enzymes in microemulsions, consisting of the surfactant Aerosol OT, and various alkane solvent and aqueous phases. All enzymes exhibited, besides an increase in specific activity, an upshift of the temperature optimum of the catalysed reaction. The temperature optimum could be further shifted by variation of the chain length of the solvent used and/or the addition of compatible solutes to the aqueous phase. Under optimised conditions, catalytic reactions of enzymes from mesophilic microorganisms had temperature optima in the range generally obtained with enzymes from thermophilic organisms.
authors.affiliation: Institut für Mikrobiologie und Genetik, Universität Göttingen, Grisebachstrasse 8, 37077 Göttingen, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Mlejnek
authors.forename: B
authors.initials: B
authors.lastname: Seiffert
authors.forename: T
authors.initials: T
authors.lastname: Demberg
authors.forename: M
authors.initials: M
authors.lastname: Kämper
authors.forename: M
authors.initials: M
authors.lastname: Hoppert
mesh_terms: D000426:Alcohol Dehydrogenase / Q000378:metabolism*; D000473:Alkanes / Q000737:chemistry; D002384:Catalysis; D004143:Dioctyl Sulfosuccinic Acid / Q000737:chemistry; D004655:Emulsions; D004795:Enzyme Stability; D006094:Gram-Positive Bacteria / Q000201:enzymology; D006864:Hydrogenase / Q000378:metabolism*; D007770:L-Lactate Dehydrogenase / Q000378:metabolism*; D043367:Ralstonia / Q000201:enzymology; D012441:Saccharomyces cerevisiae / Q000201:enzymology; D013696:Temperature; D014867:Water / Q000737:chemistry
chemical_list: D000473:Alkanes; D004655:Emulsions; D014867:Water; D004143:Dioctyl Sulfosuccinic Acid; D000426:Alcohol Dehydrogenase; D007770:L-Lactate Dehydrogenase; D006864:Hydrogenase