title: Increased stability of malate dehydrogenase from Halobacterium salinarum at low salt concentration in reverse micelles.
abstract: The stability of malate dehydrogenase (hMDH) from Halobacterium salinarum in aqueous medium at low salt concentrations (1 and 0.5 M NaCl) was studied at 4 degrees and 25 degrees C. The results showed that hMDH was more stable at the higher salt concentration and the low temperature. hMDH was introduced into reverse micelles of hexadecyltrimethylammonium bromide in cyclohexane with 1-butanol as co-surfactant. The hMDH stability in this system was studied at two omega(0) ([H(2)O]/[surfactant]) values and the effects of salt concentration, presence of substrate and dilution before or after its introduction into reverse micelles were examined. The results showed that the half-life of hMDH dissolved in buffer with 1 M NaCl was 12-50 days in reverse micelles (depending on the various conditions), in contrast to only about 1 day in aqueous medium at 25 degrees C. These observations indicate that reverse micelles provide a microenvironment that allows a much greater stability of this enzyme compared with an aqueous medium.
authors.affiliation: División de Bioquímica, Facultad de Ciencias, Universidad de Alicante, Alicante, Spain. sonsoles.piera@mail.tju.edu
authors.forename: Sonsoles
authors.initials: S
authors.lastname: Piera-Velázquez
authors.forename: Frutos
authors.initials: F
authors.lastname: Marhuenda-Egea
authors.forename: Eduardo
authors.initials: E
authors.lastname: Cadenas
mesh_terms: D020001:1-Butanol; D019843:Archaeal Proteins / Q000737:chemistry* / Q000187:drug effects; D000077286:Cetrimonium; D002593:Cetrimonium Compounds; D003510:Cyclohexanes; D004655:Emulsions; D006207:Half-Life; D019617:Halobacterium salinarum / Q000201:enzymology*; D007038:Hypotonic Solutions / Q000494:pharmacology; D008291:Malate Dehydrogenase / Q000737:chemistry* / Q000187:drug effects; D008823:Micelles; D011489:Protein Denaturation; D012965:Sodium Chloride / Q000494:pharmacology; D012997:Solvents; D014867:Water
chemical_list: D019843:Archaeal Proteins; D002593:Cetrimonium Compounds; D003510:Cyclohexanes; D004655:Emulsions; D007038:Hypotonic Solutions; D008823:Micelles; D012997:Solvents; D014867:Water; D012965:Sodium Chloride; D020001:1-Butanol; D008291:Malate Dehydrogenase; D000077286:Cetrimonium