Mechanisms biological

The fixation reaction involves eight single electron-transfer reactions, consistent with the apparent limiting stoichiometry [Eq. (85)]. However, this does not exclude the possibility that the electrons are transferred to dinitrogen within the enzymes in groups of two or more. 

Dihydrogen is evolved prior to reduction of dinitrogen, as exemplified by transition metal complexes [Eqs. (86) and (87)]. 

After five electrons have been transferred (at E4), then the intermediate state (Mo=NNH2) (see Section VI,B) is formed. This does not, 

SCHEME 24. Proposed trihydride molybdenum site of nitrogenase and the reactions resulting in H2H formation. 

If it is assumed that each state E has an equal probability, then the amount of hydrazine produced suggests that the hydrazido(2-) intermediate concentration corresponds to one-eighth the total molybdenum content of the enzyme. This is consistent with one dinitrogen bound per molybdenum, so that dinitrogen does not bridge between the two molybdenum atoms present in the large protein (329). 

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As a conclusion one can say that the distinction of islands of specific activity from within a sea of baseline toxicity, with each island representing a local chemical biological mechanism domain, is still a challenge to be solved by scientists working both experimentally and computationally. 

Mechanisms of Leukocyte Adsorption. The exact mechanism of leukocyte adhesion to filter media is not yet fuUy understood. Multiple mechanisms simultaneously contribute to the adhesion of cells to biomaterials, however, physical and biological mechanisms have been distinguished. Physical mechanisms include barrier phenomenon, surface tension, and electrostatic charge biological mechanisms include cell activation and cell to cell binding. 

R. N. Loeppky and Y. T. Bao, in I. K. O NeiU and H. Bartsch, eds., Nitroso Compounds Biological Mechanisms, Exposures and CancerEtiology, International Agency for Research on Cancer, Lyon, France, 1992, pp. P16a—b. 

Quantum, by contrast, converted an ethylene—carbon monoxide polymer into a polyester-containing terpolymer by treatment with acidic hydrogen peroxide, the Baeyer-Villiger reaction (eq. 11). Depending on the degree of conversion to polyester, the polymer is totally or partially degraded by a biological mechanism. 

Supplement "Corticosteroids Their Biological Mechanisms and AppHcation to the Treatment of Asthma", Am. Rev. Respir. Dis. 141, SI (1990). 

Biological. Several recent patents have claimed the production of ethylene oxide from a wide variety of raw materials using enzymatic catalysts (221—224). However, no commercial production routes based on biological mechanisms have been proposed. 

In order to discuss the biological mechanisms involved in the aetiology of genital tract malformations, testicular cancer and lowered sperm counts, some knowledge of the processes involved in the differentiation and development of the male reproductive tract and determination of normal testicular function is required. An early embryo has the potential to develop either a male or a female... 

The interactions may be physicochemical without the participation of biological mechanisms for example, deep lung exposure to highly soluble irritative gases, such as sulfur dioxide, may become enhanced due to adsorption of the gas onto fine particles. Biological interactions may occur at all stages and body sites. For example, toxicity is increased when adverse effects are due to some reactive metabolic intermediate and exposure to another agent stimulates its metabolic activation (enzyme induction). 

The Chemical Regulation of Biological Mechanisms, (ed. Creighton, A, M., Turner, S.), The Royal Soc. of Chem. Special Publication No. 42, London 1982... 

Target Contrast medium Commercial product or experimental Biological mechanism Reference... 

Biotransformation Conversion of a chemical into one or more products by a biological mechanism (predominantly by enzyme action). 

Suggest syntheses for TMs (9) and (10) needed as intermediates TM (9) in the synthesis of brominated hydroxy benzoic acids and TM (10) in the synthesis of model compounds for studying biological mechanisms of ester hydrolysis,... 

Root DE, Flaherty SP, Kelley BP, Stockwell BR. Biological mechanism profiling using an annotated compound library. Chem Biol 2003 10 881-92. 

Biological Mechanisms for Association with Organic Components of Soil and Sediment... 

Like age, the WBC count at presentation is a reliable indicator of CR rate and outcome. WBC count is indicative of tumor burden, although the underlying biologic mechanisms that account for the unfavorable outcomes associated with an elevated WBC count are unclear. Patients with WBC counts of less than 50 X 103/jliL (50 x 109/L) are considered standard risk, and a higher WBC count at presentation is associated with higher risk of treatment failure (Table 92-6). 

Krinsky NI, Landrum JT, and Bone RA (2003), Biologic mechanisms of the protective role of lutein and zeax-anthin in the eye, Ann. Rev. Nutr. 23 171-201. 

Krinsky, N. I. (2002). Possible biologic mechanisms for a protective role of xanthophylls. J. Nutr. 132(3) 540S-542S. 

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