Binding with proteins and membranes

The monomeric species, not the micellar form of surfactant, are involved in the surfactant binding with proteins and membranes (64). The free monomeric concentration of the surfactant, therefore, determines the amount bound. Nonionic surfactants are bound in smaller number and with lower affinity, partly because of the generally low CMCs for these surfactants as... 

The volumes reflect binding to proteins and membranes. Only fluconazole, with its moderate lipophilicity and neutral character (low nonspecific binding), has a volume of distribution related to physiology (total body water). 

The role of protein in photoactivation was investigated using trypsi-nized membranes and 1 uM DCMU. In the absence of DCMU the whole chain electron transport as also PS II was equally affected in trypsinized chloroplasts. 1 uM DCMU protected PS II and whole chain activities from photoinactivation only in the trypsinized membranes. As DCMU binds with protein and trypsin selectively degraded this protein, DCMU protection against photoinactivation to Qq could not be seen, as DCMU had little or no to bind with. The DCMU protection against photoinactivation could be interpreted... 

Clearly, the techniques discussed in this chapter are most useful in combination with other complementary approaches to the study of molecular motion and interactions. Examples other than those already alluded to are the chemical kinetics related to drug-DNA binding (47), and the accessibility of probes associated with proteins and membranes to diffusable quenchers (18,37). The search will continue for more sensitive modes of measurement and for reporter groups which exert a minimal perturbation of the target molecules. 

Ca2+ influx initiates protein and membrane associations by several different mechanisms. Allosteric regulation of the hydrophobicity of protein-binding surfaces frequently occurs. One of the best studied examples is the Ca2+-dependent binding of calmodulin to other proteins (Ch. 22). Annexins are a family of proteins that exhibit Ca2+-dependent associations with cell membranes through direct interaction with phospholipids, and conversely, interactions with phospholipids increase their affinities for Ca2+ [7]. 

In this chapter we will mainly focus on questions related to the S-donor ligands. So, how can platinum reach the DNA after administration of the drug, after or despite its reactions with rescue agents, its transport through the cell membrane, and its possible binding to proteins and peptides as an intermediate ... 

In instances where nature has not provided an appropriate fluorophore, one can often add an extrinsic label. The earliest probes include dansyl chloride [1] and ANS (Fig. 3). Dansyl chloride can be covalently attached to macromolecules by reaction with amino groups. ANS often binds spontaneously but non-covalently to proteins and membranes, probably by hydrophobic and electrostatic interactions. The emission of both molecules is sensitive to the polarity of the surrounding environment. ANS is nearly non-fluorescent in water, but fluoresces strongly upon association with serum albumin, immunoglobulins and other proteins. A wide variety of covalent and non-covalent probes are available [2,3]. 

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