SummaryThe penetration of bovine serum albumin and penicillin acylase into Amberlite XAD7 beads was determined by staining split beads. The rates of penetration were measured and correlated with a theoretically derived equation.
SummaryPenicillin acylase has been immobilized to carboxymethylcellulose and to the resin Amberlite XAM. The reaction kinetics of the enzyme were affected by both intrinsic (molecular) and microenvironmental effects. The Michaelis constant for the enzyme increased after immobiiiation as a result of an intrinsic effect of the reagent, glutaraldehyde, used for enzyme immobilization. Microenvironmental effects were of two types: diffusional limitation of access of substrate and a reaction-generated pH depression in the support particles. This depression of internal pH was observed in all the preparations and could be reduced by addition of pH buffering salts to the reactor. An adsorbed pH-indicating dye was used to determine the surface and internal pH of particles of XAW-penicillin acylase under various reaction conditions. The extent of diffusional rate limitation in XAD7-penicillin acylase was related to the penetration depth of protein into the porous support particles. The penetration depth of protein and thus the diffusional limitation of the reaction rate could be controlled by the conditions of preparation of the immobilized enzyme. A staining technique was used to observe the location of the protein.
SummaryImmobilized penicillin acylase has been used for the deacylation of benzylpenicillin at 37°C in a continuous reactor consisting of four I liter stirred tanks connected in series. There was good agreement between the predicted and actual conversions obtained in each tank under steady-state conditions. The operational stability of the immobilized enzyme in the tanks depended on the pH and the rate of addition and concentration of alkali needed to neutralize the acid produced during the reaction.At pH 7 with the addition of 2M NaOH, the half-life for enzyme stability was greater than 400 hr in all tanks. This was over half the value for the immobilized enzyme when stored at 37°C and pH 7.
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