Effect of shear on membrane-associated enzymes: Studies of the release of intracellular protein and of the progesterone 11alpha-hydroxylase complex from rhizopus nigricans.
Rhizopus nigricans ATCC 6227b grown in either shake flasks or a fermentor was sheared in a concentric cylinder viscometer. The cells grown in shake flasks were found to be more susceptible to disruption by shear than those grown in the fermentor. Cells resuspended in a medium containing reduced glutathione and EDTA were found to be more easily disrupted than cells resuspended in 0.5% NaCl. The optimum condition for disruption of shake flask cells grown in the former medium with retention of progesterone 11alpha-hydroxylase activity was a laminar shear rate of 4300 s(-1), for a period of 3 min at 4 degrees C. During the first 30 s the apparent viscosity was found to decrease significantly with applied shear.
Department of Chemical and Biochemical Engineering, University College London, London WC1E 7JE, England.
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Talboys
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Dunnill