Tissue and organelles

Another possibility for extending the field of biosensors is to employ sections of animal or plant tissue as sources of enzymatic material. Tissue has the advantage of cohesion, and has a structure that is robust enough to be attached directly to the transducer without having to resort to protein immolnlization techniques. 

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Electron microscopy permits the detailed study of cell relationships within tissues and organelles within cells. Two ultrastructural techniques in which gold probes have proven invaluable are mununocytochemistry and in situ hybridization, and these will be described here. Until 1980, peroxidase was the marker of choice, but now colloidal gold is almost universally used. The advantages of colloidal gold are that ... 

Cytochrome P-450 is a hemoprotein that is distributed widely in nature in animal tissue and organelles, and in plants and microoganisms. Its main function lies in the monooxygenation of lipophilic substances, in which two electrons are taken up from NADPH with the reduction of one atom of dioxygen to water and insertion of the other into the substrate (equation 79). 

This review has stressed the need to isolate and chemically characterize the structures of the polymers of primary cell walls. Emphasis must be placed on working with cell wall polymers rather than with polymers obtained from other tissues and organelles. It is also important to obtain polymers from homogeneous preparations of primary cell walls rather than from walls isolated from tissues containing a mixture of wall types. Much of the early work on characterizing cell wall polymers was done with heterogeneous wall preparations. The availability of easily... 

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