Interaction nonspecific

Another complication of the trNOE method may be the possibility that the ligand interacts nonspecifically with the protein. This has been discussed by Rao and coworkers [23]. Specificity of the interaction can best be demonstrated by a competition experiment with a strong binder. 

Acute toxicity to aquatic species can be rationalized mechanistically by one of two types of interactions nonspecific mechanisms (called narcosis) or specific mechanisms. The latter involves specific interactions, such as covalent electrophilic reactions with biological macromolecules, or specific noncovalent interactions that cause toxicity, such as uncoupling of phosphorylative oxidation, among others. Most chemicals that are toxic to aquatic organisms are narcotic. Some have both narcotic and specific mechanisms. A narcotic chemical enters the cellular membranes of the organism and, by its mere presence, causes perturbations in the membranes to the extent that alterations in the function of the membranes occur, resulting in toxicity. 

A model that is consistent with these observations of the action of trypsin and phospholipase A and with the discontinuities in the All-composition curves (Figures 2 and 3) is one in which the lipid monolayer is not a continuous palisade of uniformly oriented lipid molecules but rather an assembly of surface micelles. In this model, proposed by Colacicco (4, 5), the protein first comes into contact with the lipid molecules at the periphery of the surface micelles and then inserts itself as a unit between them. This is the basis for the generalized nonspecific interaction between lipids and proteins which results in increase of surface pressure. One may thus explain the identical All values obtained with films of lecithin and 80 mole % lactoside by picturing the lecithin molecules outside and the lactoside molecules inside the surface micelles. In this model lecithin prevents the bound lactoside from interacting nonspecifically with globulin and produces the same increase in pressure as with a film of pure lecithin. In the mixed micelle the lactose moiety of the lactoside protrudes into the aqueous subphase. Contact of the protein with these or other nonperipheral regions of the surface micelle would not increase the surface pressure. 

Antibody microarrays are the most common target microarrays. Target microarrays consist of different proteins printed onto planar-solid surfaces (7,8). In general, these arrays have found several applications in clinical studies because they allow identification of specific protein profiles. One of the major drawbacks of antibody microarrays is the need for oriented immobilization of the capture reagent onto the surface in order to avoid steric hindrance with the specific proteins presented in the sample. Therefore, to solve this problem, several strategies have been described that implied that chemical groups promote orientation and avoid cross-linkers that can interact nonspecifically with the query protein. Another important disadvantage is the loss of activity of proteins upon immobilization (9—11). 

Both avidin and its bacterial counterpart, streptavidin, are standard reagents for histochemical procedures. Avidin is a 66-kDa, positively charged glycoprotein with an isoelectric point of about 10.5 (4). The positively charged residues and the oligosaccharide component of avidin can interact nonspecifically with... 

Fig. 10.2.3. Structures of the inclusion complex (interaction specific for the CyD structure) and the complex with hydrogen bonding (interaction nonspecific for the CyD structure).

Potentially toxic nanoscale interactions Nonspecific uptake Inactivation of therapeutic proteins... 

Interaction Nonspecific Depends on the reactivity of the adsorbent and the adsorbate... 

Group A Molecules. These molecules have spherically symmetric electron shells. Examples are noble gases and the saturated hydrocarbons, which have only sigma bonds between the carbon atoms. Molecules of this type interact nonspecifically, through dispersive forces resulting from concordant electronic motion in the interacting molecules. 

It may be instructive to contrast the interactions between the ribosome and the nucleosomal particle which contains DNA. As noted above, the eukaryotic ribosome contains approximately 70 different proteins, and there is experimental evidence that the proteins interact with specific sequences of RNA. The nucleosome particles, which are the subunits comprising the chromatin, contain five major histone proteins, most represented twice, which interact nonspecifically with 140-170 DNA base pairs. 

---