Formaldehyde hydrogenase and formate dehydrogenase were purified 130-fold and 19-fold respectively from Candida boidinii grown on methanol. The final enzyme preparations were homogeneous as judged by acrykdmide gel electrophoresis and by sedimentation in an ultracentrifuge. The molecular weights of the enzymes were determined by sedimentation equilibrium studies and calculated as 80000 and 74000 respectively. Dissociation into subunits was observed by treatment with sodium dodecylsulfate. The molecular weights of the polypeptide chains were estimated to be 40 000 and 36000 respectively.The NAD-linked formaldehyde dehydrogenase specifically requires reduced glutathione for activity. Besides formaldehyde only methylglyoxal served as a substrate but no other aldehyde tested. The K, values were found to be 0.25 mM for formaldehyde, 1.2 mM for methylglyoxal, 0.09 mM for NAD and 0.13 mM for glutathione. Evidence is presented which demonstrates that the reaction product of the formaldehyde-dehydrogenase-catalyzed oxidation of formaldehyde is Sformylglutathione rather than formate. The NAD-linked formate dehydrogenase catalyzes specifically the oxidation of formate to carbon dioxide, The K, values were found to be 13 mM for formate and 0.09 mM for NAD.

Intracellular proteins with catalytic or biological activity are of growing importance for developments in enzyme technology, as well as for the production of mammalian proteins by recombinant‐DNA technology. The release of these proteins from microorganisms is an important unit operation, as it is the first step in their isolation. Gram‐scale disruption of microorganisms can be performed by a variety of established methods based on chemical, enzymatic, physical, or mechanical principles. For the large scale disruption of microorganisms, mechanical disintegrators, such as high‐speed agitator bead mills or high‐pressure industrial homogenizers, are commonly employed. Both types of equipment were designed originally for other tasks; in the paint industry or in the milk industry, respectively. Therefore, it appeared necessary and possible to improve design and performance for the application in cell disintegration. The goal is a uniform exposure of the microbial cells and a minimal exposure of solubilized protein to high shear forces, in order to obtain high yields and to avoid the generation of too small cell wall fragments, which are difficult to separate. Both types of machines have been investigated for the disintegration of different microbial cells and the influence of the operating parameters analyzed on protein solubilization and enzyme yield. We will summarize the state of the art and discuss new data to illustrate trends in process development.

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