Molecular similarity principle

Horvath, D. and Jeandenans, C. (2003) Neighborhood behavior of in silico structural spaces with respect to in vitro activity spaces - a novel understanding of the molecular similarity principle in the context of multiple receptor binding... 

Tape >System of Analysis. A tape system which is used widely for analysis in the Pediatric Laboratory is a system whose principle was developed by the author. A reagent is placed on a paper tape. The paper is covered with a membrane, such as cellophane, cellulose nitrate or cellulose acetate, porous to low molecular weight substances. Finally, the serum is placed above the porous membrane, so that diffusion of the components of serum take place and a stain is produced on the paper (60). This principle has been incorporated for example, with glucose oxidase, in the conmercially available Dextro-Sticks. In addition, a similar principle is being applied by some for the analysis of components in urine (Ames Co., South Bend, Indiana). 

TRANSITION STATE THEORY POTENTIAL ENERGY SUREACE HAMMOND PRINCIPLE TRANSITION STRUCTURE CHEMICAL KINETICS TRANSITION-STATE ANALOGUES MOLECULAR SIMILARITY... 

Key Words Chemical database compound selection library design molecular diversity molecular similarity neighborhood behavior similar property principle similarity searching. 

In the context of compound partitioning, it should also be considered that relationships between structural and biological similarity can differ significantly. Much of the current molecular similarity research is based on the fundamental, and rather intuitive, similar property principle (18), which states that compounds with similar structures should generally have similar biologically activity. On the other hand, it is well known that minute structural modifications of active com-... 

It should be noted that the general understanding of molecular similarity goes beyond simple structural similarity and extends to biological activity, in accord with the so-called Similar Property Principle (Johnson and Maggiora 1990) postulating that molecules having similar structures and properties should also exhibit similar activity... 

In summary, it has been demonstrated that ISEs can be designed by employing molecular recognition principles. In particular, the feasibility of using hydrophobic vitamin B12 derivatives and electropolymerized porphyrin films in the development of polymer membrane anion-selective electrodes has been demonstrated. The studies indicated that the changes in the selectivity of these ISEs can be explained by the difference in structure of the ionophores. In addition, it was shown that by electropolymerization of a cobalt porphyrin, anion-selective electrodes can be prepared that have extended lifetimes compared with PVC-based ISEs, which use a similar compound as the ionophore. 

A similar principle is applied in dispersion polymerization in ionic liquids produced particles are in sub-micron range (41,42). The monomer, initiator and colloidal stabilizer are soluble in the liquid medium, but the obtained polymer is not. Different kinds of ionic liquids may be used, such as for styrene l-butyl-3-methylimidazolium tetrafluoroborate or N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide. In general, radical polymerization in ionic liquids provides higher polymerization rate and higher molecular weights than the process in bulk or organic solvents (homogenous system). 

A theoretical foundation of molecular similarity analysis is the assumption of neighborhood behavior ,which refers to the tendency of molecules with globally similar structures to exhibit similar biological activity. The well-known similarity-property principle (SPP) of Johnson and Maggiora expresses this paradigm and promotes a holistic view of molecular structure and properties. Molecular similarity applications assume that chemical similarity can be related to biological activity in a meaningful manner. However, the success of this approach ultimately depends on the way molecular similarity is defined. 

Molecular similarity and diversity methods have been developed based on the principle that similar molecules exhibit similar activi-ties/properties (l).Molecular similarity is a key concept in the identification of new molecules that have similar biological activity to one or more molecules of known activity. Molecular diversity concepts are used to explore "chemical space," with the scope of application ranging from a particular structure/reac-tion to a large database of different molecules. The process of evaluating similarity and diver-... 

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