Biological relevance

The adliesion and fiision mechanisms between bilayers have also been studied with the SEA [M, 100]. Kuhl et al [17] found that solutions of short-chained polymers (PEG) could produce a short-range depletion attraction between lipid bilayers, which clearly depends on the polymer concentration (fignre Bl.20.1 It. This depletion attraction was found to mduce a membrane fusion widiin 10 minutes that was observed, in real-time, using PECO fringes. There has been considerable progress in the preparation of fluid membranes to mimic natural conditions in the SEA [ ], which promises even more exciting discoveries in biologically relevant areas. 

The proportionahty constant y is called the gyromagnetic ratio which is a function of the magnitude of the nuclear magnetic moment. Therefore each isotope having a net nuclear spia possesses a unique y. The y of some biologically relevant nuclei can be found ia Table 3. 

Table 3. Gyromagnetic Ratios for Biologically Relevant Nuclei ...

The methodological advances just presented have brought the field of nucleic acid force field calculations to a point where results from the calculations can be used with reasonable confidence to aid in the interpretation of experimental data as well as to be used for scientific investigations that are not accessible to experiment. Accordingly, a number of studies based on MD simulations, as well as other methods, have been undertaken to study a wide array of biologically relevant events associated with DNA. A brief overview of some of these efforts follows. 

Central to the quality of any computational smdy is the mathematical model used to relate the structure of a system to its energy. General details of the empirical force fields used in the study of biologically relevant molecules are covered in Chapter 2, and only particular information relevant to nucleic acids is discussed in this chapter. 

Because of possible catalytic and biological relevance of metal-sulfur clusters, several such compounds of cobalt have been prepared. The action of H2S or M2S (M = alkali metal) on a non-aqueous solution of a convenient cobalt compound (often containing, or in the presence of, a phosphine) is a typical route. Diamagnetic [Co6Ss(PR3)6] (R = Et, Ph) comprise an octahedral array of metal atoms (Co-Co in the range 281.7 to 289.4pm), all faces capped by atoms,and show facile redox behaviour... 

Electronic structure methods are aimed at solving the Schrodinger equation for a single or a few molecules, infinitely removed from all other molecules. Physically this corresponds to the situation occurring in the gas phase under low pressure (vacuum). Experimentally, however, the majority of chemical reactions are carried out in solution. Biologically relevant processes also occur in solution, aqueous systems with rather specific pH and ionic conditions. Most reactions are both qualitatively and quantitatively different under gas and solution phase conditions, especially those involving ions or polar species. Molecular properties are also sensitive to the environment. 

The macrocyclic hexamine [18]aneN6 was further found to recognize catechol, catecholamines and biologically relevant compounds (see Chart II)64). It interacts with all of these donor compounds in neutral pH solutions to form 1 1 complexes, which were determined polarographically. The stability constants pL are summarized in Table 6. 

Cellular screening systems can be developed with primary human cells cultured in biologically relevant contexts. The outputs of these systems are focused sets of biologically relevant parameters (gene transcription, protein... 

The steroid hormone 1,25-dihydroxy vitamin D3 (calcitriol) slowly increases both intestinal calcium absorption and bone resorption, and is also stimulated through low calcium levels. In contrast, calcitonin rapidly inhibits osteoclast activity and thus decreases serum calcium levels. Calcitonin is secreted by the clear cells of the thyroid and inhibits osteoclast activity by increasing the intracellular cyclic AMP content via binding to a specific cell surface receptor, thus causing a contraction of the resorbing cell membrane. The biological relevance of calcitonin in human calcium homeostasis is not well established. 

The challenge in the synthesis of chemical libraries is the vast number of different, potentially drug-like small molecules which is estimated to be as high as 1060. As all of these molecules can never be synthesized and tested, it is essential to define criteria for the composition of libraries spanning the biologically relevant areas of the chemical space most efficiently. An important criterion of a compound library is its chemical diversity, a term describing the similarity or dissimilarity of all library components. Thus, chemical diversity expresses how well a library represents all theoretical possibilities within the chemical property space. A library with low... 

In cell free systems or isolated cells, some enzymes of the arachidonate cascade can also recognize AEA and 2-AG as substrates, thereby producing the corresponding lipoxygenase and cyclooxygenase-2 derivatives. However, these metabolites have not yet been isolated from tissues and their biological relevance is still unknown. 

Biological Relevance and Emerging Roles for Mammalian TRP Channels... 

Do binucleating ligands have a biological relevance D. E. Fenton, Adv. Inorg. Bioinorg. Mech., 1983,2,188 (264). 

The synthesis of pyrido[2,3-d]pyrimidines has attracted considerable interest in heterocyclic chemistry. This ring system constitutes a deaza-analogue of the pyrazino[2,3-d]pyrimidine heterocychc core of fohc acid, analogues which can exhibit a wide range of biological properties as folate antagonists. Thus, the synthesis of this motif by MCR imder microwave-assisted conditions has the potential to rapidly introduce diversity into a biologically relevant scaffold. 

In summary, microwave irradiation has been applied to several soHd-phase syntheses of a large number of diverse and biologically relevant heterocycies. 

A library of biologically relevant 2-aryl-3-aminoimidazo[l,2-fl]pyridines and 2-aryl-3-aminoimidazo[l,2-fl]pyrazines was created using a combina-... 

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