An endoglucanase homolog from the hyperthermophilic archaeon Pyrococcus horikoshii was expressed in Escherichia coli, and its enzymatic characteristics were examined. The expressed protein was a hyperthermostable endoglucanase which hydrolyzes celluloses, including Avicel and carboxymethyl cellulose, as well as ␤-glucose oligomers. This enzyme is the first endoglucanase belonging to glycosidase family 5 found from Pyrococcus species and is also the first hyperthermostable endoglucanase to which celluloses are the best substrates. This enzyme is expected to be useful for industrial hydrolysis of cellulose at high temperatures, particularly in biopolishing of cotton products.In the textile industry, cellulases have been used in large quantity for biopolishing of cotton products. This process is essential for removing fuzz and giving a soft touch and clean appearance to the fabrics. The enzymes that are presently used for this purpose are mesophilic cellulases from fungi, and their optimum reaction temperatures are between 50 and 55°C. If they are replaced by a hyperthermostable enzyme with an optimum temperature close to 100°C, which will make it possible to treat cotton products in steam, the processing will be much more simple, quick, and efficient than in the presently employed method. Desizing, the step to remove starch from the fabrics, is performed at temperatures at least 70°C, and higher temperatures are preferred. Because amylases active at these temperatures are available, this process is performed at temperatures higher than 70°C. However, cellulase treatment, which usually follows desizing, is performed at lower temperatures, since a cellulase that is active and stable in this temperature range has not been available. If such a hyperthermostable cellulase is introduced, it will be possible to combine desizing and biopolishing in a single step.For the purpose of producing such a hyperthermostable cellulase, we investigated the possibility of utilizing the genetic resources of hyperthermophilic archaea. Pyrococcus horikoshii

The selective and stable conversion of ethene to propene, 3C 2 H 4 f 2C 3 H 6 , was found on Ni-loaded mesoporous silica catalysts in a continuous gas-flow system at around 673 K and atmospheric pressure. The one-path conversion of ethene was 68%, and the propene selectivity was 48%. Nickel ion alone showed the specific activity for the reaction among 13 kinds of metal ions examined. The reaction mechanism was discussed from the viewpoints of metathesis and decomposition.

Hydrolysis of methyloleate was optimized using lipase from Chromobacterium viscosum immobilized on IRC-50. The optimization was studied by a statistical methodology using response surface methodology (RSM). The cumulative interactive effect of substrate, water concentration and time was studied in optimizing the hydrolysis of methyloleate. The interactive effect of substrate-time was found to be signi®cant compared to substrate-water and time-water interactions. A well correlation was observed between the optimum values obtained from the response surface contour plots and from the quadratic regression model equation. The optimal values obtained for substrate, water and time were found to be in the experimental range chosen.

No abstract

From the genome sequence data of the thermophilic archaeon Pyrococcus horikoshii, an open reading frame was found which encodes a protein (332 amino acids) homologous with an endoglucanase from Clostridium thermocellum (42% identity), deblocking aminopeptidase from Pyrococcus furiosus (42% identity) and an aminopeptidase from Aeromonas proteolytica (18% identity). This gene was cloned and expressed in Escherichia coli, and the characteristics of the expressed protein were examined. Although endoglucanase activity was not detected, this protein was found to have aminopeptidase activity to cleave the N-terminal amino acid from a variety of substrates including both N-blocked and non-blocked peptides. The enzyme was stable at 90³C, with the optimum temperature over 90³C. The metal ion bound to this enzyme was calcium, but it was not essential for the aminopeptidase activity. Instead, this enzyme required the cobalt ion for activity. This enzyme is expected to be useful for the removal of N K -acylated residues in short peptide sequence analysis at high temperatures.z 1999 Federation of European Biochemical Societies.