Degradation interacting molecules

The importance of the processes set in motion by a novel chemical suggests that when assessing how risky a particular novel chemical is we should think about how it will degrade, interact with other molecules, and fit into natural processes... 

Fig. 10.2 Delivery systems for therapeutic proteins. Noncovalent delivery systems include adsorption and encapsulation. By using pairs of interacting molecules, it is possible to implement affinity-based immobilization. Heparin-growth factor and avidin-biotin are shown here as examples. When covalent immobilization is used, the release of the therapeutic protein is dependent on the degradation of the matrix/scaffold. Alternatively, it is possible to use protease cleavable linker for the protein deposition in order to release the growth factor in response to specific proteases.

A related mechanism of degradation involves the direct interaction of the radioactive emission with other tracer molecules in the preparation. This phenomenon is likely to occur in high specific activity compounds stored at high radiochemical concentrations in the absence of free-radical scavengers. 

Ubiquitin/Proteasome. Figure 2 Functional consequences of ubiquitin linkage. Substrates (blue bars) are linked via lysine residues (K) to ubiquitin or ubiquitin chains, (a) Attachment of chains connected via Lysines in position 48 of ubiquitin (K48) targets substrates for proteasomal degradation. In contrast modification of one (b) or multiple (c) lysines by a single ubiquitin molecule mediates novel protein interactions or initiates endocytosis. Conjugation of K63-linked polyubiquitin (d) alters protein function and can also serve as a signal for endocytosis. 

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