Jonathan Woodward

Radical pairs (RPs) are important reaction intermediates generated whenever two radicals encounter one another, a bond is cleaved homolytically or electron transfer between non-radical species takes place. The concept of a radical pair as a reaction intermediate is introduced and developed through simple pictorial analogies, indicating how RP behaviour is governed by interplay of spin and spatial motion. Such analogies are then extended to describe the experimental consequences of RPs in magneti

Microcrystalline cellulose (10 mg of Avicel/ml) was hydrolysed to glucose by different concentrations of the purified cellulase components endoglucanase (EG) II and cellobiohydrolases (CBH) I and II, alone and in combination with each other, in the presence of excess beta-glucosidase. At a concentration of 360 micrograms/ml (160 micrograms of EG II/ml, 100 micrograms of CBH I/ml and 100 micrograms of CBH II/ml) the degree of synergism among them was negligible. As the concentration of cellulase

We demonstrate, by direct, single-cell imaging kinetic measurements, that endogenous autofluorescence in HeLa cells is sensitive to the application of external magnetic fields of 25 mT and less. We provide spectroscopic and mechanistic evidence that our findings can be explained in terms of magnetic field effects on photoinduced electron transfer reactions to flavins, through the radical pair mechanism. The observed magnetic field dependence is consistent with a triplet-born radical pair and a B

Abbreviations Immobilised enzymes: absorption and covalent coupling Immobilisation of biocatalysts by metal link/chelation processes Immobilisation of cells and enzymes by gel entrapment Immobilisation of enzymes by microencapsulation Immobilised enzyme electrodes Electrochemical techniques with immobilised biological materials Immobilised cells: transformation of steroids Immobilised plant cells: preparation and biosynthetic capacity Immobilised mammalian cells in hormone detection and quantita

We present measurements of the spectrum (1--80 MHz) of the effect of a weak (approximately 500 microT) radio frequency magnetic field on the electron-hole recombination of radical ion pairs in solution. Distinct spectra are observed for the pyrene anion/dimethylaniline cation radical pair in which one or both of the radicals are perdeuterated. The radical pair mechanism is developed theoretically and shown to account satisfactorily for both the magnetic field effect and the associated magnetic i

The enzyme beta-D-glucosidase has been immobilized on concanavalin A-Sepharose to give a maximum loading of 2050 units/g dry weight of support material. The immobilized beta-D-glucosidase was also entrapped within calcium alginate gel spheres with apparently only 35% retention of activity when assayed with 10mM cellobiose. However, it was discovered that, unlike the immobilized enzyme, the entrapped immobilized enzyme was not subject to substrate inhibition up to 100mM cellobiose, suggesting tha

Abstract The inhibition of β‐glucosidase in Trichoderma reesei C30 cellulase by D ‐glucose, its isomers, and derivatives was studied using cellobiose and ρ‐nitrophenyl‐β‐glucoside (PNPG) as substrates for determining enzyme activity. The enzymatic hydrolysis of both substrates was inhibited competitively by glucose with approximate K i values of 0.5m M and 8.7m M for cellobiose and PNPG as substrate, respectively. This inhibition by glucose was maximal at pH 4.8, and no inhibition was observed a