Ture Damhus

Enzyme Catalyzed Degradation and Formation of Peroxycarboxylic Acids

The ability of hydrolases to catalyze perhydrolysis, i.e. lysis of acyl substrates with hydrogen peroxide to form peroxycarboxylic acids, has been investigated. Lipases, esterases and cholinesterases were found to catalyze perhydrolysis but the preference of the enzymes for hydrogen peroxide relative to water as nucleophile was only 10–100 fold, even in the best cases. Hence, perhydrolysis proceeds with a very low efficiency in aqueous systems. Furthermore, all lipases, esterases and cholinesterases tested degrade peroxycarboxylic acids to the corresponding carboxylic acid and hydrogen peroxide. This reaction is most pronounced in the case of lipases while less so for cholinesterases. Consequently, cholinesterases are superior to the other hydrolases studied in catalyzing net formation of peracids in aqueous systems. In organic solvents, immobilized lipases efficiently catalyze formation of peracids from either triglycerides or the parent carboxylic acid. Proteases and phospholipase A-2 were found to neit...

Determination of peroxycarboxylic acids by high-performance liquid chromatography with electrochemical detection

Abstract A sensitive high-performance liquid chromatographic method employing reversed-phase chromatography and amperometric detection of low levels of peroxycarboxylic acids is described. Detection limits of 0.1–0.6 μ M and linear dynamic ranges of at least 0.05–5 m M were obtained. As a consequence of the high sensitivity and selectivity provided by the electrochemical detector, the method is well suited for detection of various peroxycarboxylic acids even in the complex matrices represented by detergent solutions. As an illustration of the applicability of the system developed, the levels of various peroxycarboxylic acids were monitored in the course of a washing cycle performed with some commercially available detergents.

Lipase-Catalyzed Regioselective Acylation and Deacylation of Glucose Derivatives

In the development of an efficient synthesis of 1-O-decanoyl-2,3,4,6-tetra-O-acetyl-β-D-glucose (β-2) several lipase-based approaches have been explored. Among five immobilized Upases tested, the lipase from Candida antarctica proved particularly efficient for catalyzing selective hydrolysis in the 1-position of 1,2,3,4,6-penta-O-acetyl-β-D-glucose (β-1). Using triethylamine as catalyst, the hydrolysis product 2,3,4,6-tetra-O-acetyl-D-glucose (3) can be esterified with decanoyl chloride to form β-2 selectively, thereby providing an efficient chemo-enzymatic synthesis starting from readily available raw materials. Attempts to produce β-2 from β-1 by lipase-catalyzed interesterification or to esterify 3 with decanoic acid using a lipase as catalyst were unsuccessful. The latter finding was explained by the hemiacetal OH group of glucose being unable to act as nucleophile in the lysis of the lipase acyl-enzyme intermediate. Furthermore, β-2 was found to bee a too bulky substrate to fit into the active site o...

Catalytic Antibodies with Perhydrolytic Activity

Monoclonal antibodies catalyzing lysis of 4-nitrophenyl esters have been created using a phosphonate as hapten in the immunization. Among 960 hybridomas screened, 3 were found to produce antibodies catalyzing hydrolysis of 4-nitrophenyl butanoate (1). Two of the antibodies accelerate the reaction by factors of 1.3 × 104 and 1.1 × 104, respectively, while the third antibody is significantly less effective. The two catalytically most effective antibodies also catalyze perhydrolysis of 1, i.e., lysis with hydrogen peroxide, to generate peroxybutanoic acid. Perhydrolysis was found to be the predominant reaction even in dilute solutions of hydrogen peroxide. Both antibodies also catalyze hydrolysis of both 4-nitrophenyl hexanoate and decanoate, but do not catalyze hydrolysis of 4-nitrophenyl acetate. The antibodies are more selective with respect to the aromatic part of the substrate as they do not catalyze hydrolysis of 2-nitrophenyl butanoate or 4-sulfophenyl nonanoate. Furthermore, neither of the antibodies...