In the present study, partial lesions of the lower thoracic spinal cord in rats anaesthetized with halothane and nitrous oxide were made in order to elucidate which of the spinal funiculi mediate a nociceptive C fibre input to SI. Field potentials evoked by noxious CO2-laser stimulation were recorded in the left SI. Nociceptive C fibre input from the right hindpaw to SI was propagated by the dorsa

The phase behavior of different carboxylic acids/nonionic polymer/water systems has been studied. The carboxylic acids investigated are acetic acid, propionic acid, and butyric acid. The polymers used are a linear random copolymer of ethylene oxide and propylene oxide (UCON) and ethyl(hydroxyethyl)-cellulose (EHEC). These polymers display a lower critical solution temperature (LCST) in water. The

The reaction kinetics of αchymotrypsin (EC 3.4.21.1.) catalyzed esterification of N-protected phenylalanine with ethanol were studied. The enzyme was deposited on Chromosorb and reactions were performed mainly in water-saturated mixtures of ethyl acetate and heptane, but also other media were used, such as mixtures of ethyl acetate and acetonitrile. The hydrophobicity of the substrate was varied b

Esterification of N-acetyl phenylalanine with ethanol catalyzed by immobilized αchymotrypsin (EC 3.4.21.1) was studied in various reaction media. The effect of reaction medium polarity on enzymatic activity as well as equilibrium yield was measured. The reaction rate increased with increasing amounts of added water, reaching an optimum corresponding to water saturation of the reaction medium. Furt

A series of quinone-based compounds were tested for their ability to act as external electron acceptors in the 1-dehydrogenation of-αmethyl-hydrocortisone-21-acetate, with polyurethane-entrapped Arthrobacter simplex cells in buffer-saturated n-decan-1-ol. This organic solvent was needed to solubilize the steroid substrate. In aqueous medium, the conversion with free cells virtually stopped after o

When mixing chymotrypsin and a polymer, e.g. ethyl cellulose and drying them together, complexes are formed that are soluble in organic solvents. The enzyme maintains its activity and is even stabilized as compared to a preparation in which the enzyme is added as a dry powder to the solvent. In both cases, minute amounts of water are added afterwards. The system containing a polymer shows a marked

Enzymes adsorbed or deposited on porous support materials have been succesfully used as catalysts in organic media. However, the support must be chosen with great care. The support can affect the partitioning of substrates, products and water in the reaction mixture and thereby indirectly influence the catalytic properties of the enzyme. Furthermore, the support can influence both the enzyme kinet

Enzymatic reactions were performed in a modified auto-injector unit of a Shimadzu HPLC system. The reactions were analyzed by automated injections directly into the HPLC separation system. Two reactions were studied, and the enzymes mandelonitrile lyase and α-chymotrypsin were immobilized by adsorption onto a solid support, e.g., Celite and Chromosorb. The reactions were performed in various organ

The incorporation of a free fatty acid into the sn-1 position of phosphatidylcholine by lipase-catalyzed transesterification was investigated. The thermodynamic water activity of both the enzyme preparation and the substrate solution was adjusted to the same value prior to the reaction. The reaction rate increased with increasing water activity but the yield of modified phosphatidylcholine decreas

Scaling up of Lipozyme-catalyzed ester synthesis with >99% conversion and a reflux trap to remove product water from the reaction mixture is reported. Ethyl stearate was synthesized in 2000-g batch reactions from technical stearic acid. The ethyl stearate was purified to 97% by crystallization and interesterified with sunflower seed oil by means of a lipase catalyst to investigate reaction paramet

Enzymes immobilized by deposition onto a solid support at low enzyme loadings were shown to be stabilized by additives, such as proteins and PEG. The additive protects the enzyme from deactivation during immobilization. The amount of additive required to obtain full stabilization was dependent on the type of support material used and corresponded approximately to a monolayer coverage of the additi

Nucleophilic properties of amino acid amides were studied systematically in acyl-transfer reactions catalyzed by α-chymotrypsin and subtilisin from Bacillus subtilis strain 72 (subtilisin 72) using Mal-L-Ala-L-Ala-L-PheOMe and Bz-L-TyrOme as the acyl group donors. In α-chymotrypsin-catalyzed reactions in water the reactivity of the amino acid amides increases with hydrophobicity of the nucleophile