S.A. Barker

Immobilization of lipase from Candida cylindraceae and its use in the synthesis of menthol esters by transesterification.

Lipase (EC 3.1.1.3) from Candida cylindraceae has been immobilized by the cellulose-titanium chloride method, and on EP-400 polyethylene, with and without glutaraldehyde crosslinking, to give active preparations when assessed by their ability to catalyse the hydrolysis of tributyrin. In both cases, the use of glutaraldehyde crosslinking was shown to improve the stability of the preparations for repeated use. The lipase immobilized on EP-400 polyethylene was found to be effective in transesterification using tributyrin or triacetin as acyl donors with l-menthol as acceptor. The production of methyl butanoate and of methyl acetate using this immobilized preparation was in each case enhanced in the presence of Amberlite IR 47 Anion exchange resin (OH form).

The interaction of areneboronic acids with monosaccharides

Abstract The interaction of benzeneboronic acid, 4-methoxybenzeneboronic acid, and 3-nitrobenzeneboronic acid with d -glucose, d -mannose, and d -fructose at various pH values has been investigated by means of optical rotation methods. The effects of ( a ) various molar ratios of sugar and acid and ( b ) overall concentration on the extent of complex formation are reported.

Cross-linked polyacrylamide derivatives (enzacryls) as water-insoluble carriers of amylolytic enzymes

Abstract Methods are described for the water-insolubilisation of alpha- and beta-amylase by chemical coupling to two cross-linked copolymers of acrylamide. For one copolymer, coupling was effected either by diazo or isothiocyanato groups, and for the other, acid azide groups were employed. Active derivatives of alpha-amylase were prepared by diazo, isothiocyanato, and acid azide coupling, whereas active derivatives of beta-amylase could be prepared only by diazo and isothiocyanato coupling. The stabilities of the active, copolyacrylamide-bound preparations of amylase were comparable to those of the corresponding, cellulose-bound enzymes. In the case of alpha-amylase, the copolyacrylamide derivatives were more stable than the free enzyme in solution.

A Spectrophotometric method for the determination of formic acid in the periodate oxidation of carbohydrates

Abstract A spectrophotometric method of assaying formic acid, in the range 5–200μg, has been devised by using the chromophore (λ max 450 mμ) formed on heating formic acid with 2-thiobarbituric acid under acidic conditions. The method may be used to monitor formic acid production from carbohydrates during periodate oxidation, since any interfering aldehydes are reduced with sodium borohydride following termination of the reaction with ethylene glycol.

Preparation and stability of exo-amylolytic enzymes chemically coupled to microcrystalline cellulose

Abstract The preparation of active, water-insoluble derivatives of β- and γ-amylase by chemical coupling with a diazotised 3-( p -aminophenoxy)-2-hydroxypropyl ether of cellulose, and a water-insoluble derivative of β-amylase by coupling with a 2-hydroxy-3-( p -isothiocyanatophenoxy)propyl ether of cellulose is described. The activity retained on insolubilisation is considerably higher than that commonly retained on water-insolubilisation of hydrolytic enzymes active against macromolecular substrates. It is suggested that this is connected with the exo-hydrolytic character of β- and γ-amylase. The insoluble enzymes are relatively more resistant to heat denaturation than the free enzymes in solution.

β-d-glucosidase chemically bound to microcrystalline cellulose☆

Abstract Almond β- d -glucosidase reacts with cellulose carbonate to give an enzymically active, insoluble, enzyme derivative. The coupling reaction is pH-dependent, the optimum being at pH ∼7.8. The bound enzyme is more stable than the free form to incubation at 37°. The pH-activity profile for the bound is similar to that for the free enzyme.

Preparation and properties of α-amylase chemically coupled to microcrystalline cellulose

Abstract Methods are reported for the preparation of water-insoluble derivatives of α-amylase, in which the enzyme is covalently linked to microcrystalline cellulose. Coupling was effected via diazotised 3-(p-aminophenoxy)-2-hydroxypropyl ethers and 2-hydroxy-3-(p-isothiocyanatophenoxy)propyl ethers of cellulose having different degrees of substitution; low substitution results in higher retention of α-amylase activity. The water-insoluble enzyme shows greater heat stability than the native α-amylase, 20% of the original activity remaining after 7 days at 45°.

Galactomannan peptides of Trichophyton mentagrophytes.

Abstract Glycopeptides from deep and surface cultures of Trichophyton mentagrophytes have been separated and their sugar and amino acid components assayed. Aspects of some structure-biological activity relationships are presented.

The use of poly(4-vinylbenzeneboronic acid) resins in the fractionation and interconversion of carbohydrates

Abstract Poly(4-vinylbenzeneboronic acid) resins have been prepared and used as chromatographic packings in the fractionation of carbohydrates with water as the eluent. The effect of the pH and temperature of the eluent on the fractionations was investigated. These resins have also been used to displace the pseudo-equilibrium established in aqueous alkali between d -glucose, d -fructose, and d -mannose to give high yields of d -fructose, and the use of a model reactor for the preparation of d -fructose is described.

Separations of isomeric polyols.

Abstract A method is presented for the automated determination of erythritol and threitol, which may be present in mixtures obtained from the partial oxidation of hexitols or oxidation of polysaccharides, by chromatography on Dowex 1 (molybdate). Separations of allitol and ribitol from their isomers are also described. Chromatography on Dowex 1 (sulfate) allowed the separation of propane-1,2-diol, glycolaldehyde, glycerol, erythritol, and xylitol.