Activated characterization

B. Bauvois, J. Sanceau, J. Wietzerbin, Human U937 Cell Surface Peptidase Activities Characterization and Degradative Effect on Tumor Necrosis Factor-a , Eur. J. Immunol. 1992, 22, 923-930. 

LO activity is found in a variety of mammalian cells, most notably leukocytes, with the enzymes from neutrophils and the rat basophilic leukemia (RBL-1) cell line being the most studied several have been purified and cloned [5]. 5-LO is a cytosolic enzyme which requires calcium, ATP and additional uncharacterized cell components for optimal activity. Characterization and kinetic studies with 5-LO enzymes are often difficult, because of self-inactivation and complex cofactor requirements. 

In most kinetic investigations, one assumes the enzyme remains stable over the course of the measurement. When this is the case, corrective measures must be taken to obtain valid kinetic data. A useful test for any enzyme system is to plot enzyme activity versus time. This is readily accomplished by using a standardized assay (usually at optimal or saturating substrate concentrations) to measure the enzyme s specific activity periodically during the course of some experiment. This approach may fail to detect a reduction in activity characterized by lower affinity for substrate however, use of a subsaturating substrate concentration in a time-course study will reveal this behavior. 

LAR removes the 4-hydroxyl from leucoanthocyanidins to produce the corresponding 2,3-tran5-flavan-3-ols, e.g., catechin from leucocyanidin. Despite early biochemical characterization, it is only recently that a LAR cDNA was isolated and the encoded activity characterized in detail. Tanner et al. purified LAR to homogeneity from Desmodium uncinatum (silverleaf desmodium), and used a partial amino acid sequence to isolate a LAR cDNA. The cDNA was expressed in E. coli, N. tabacum, and Trifolium repens (white clover), with the transgenic plants showing significantly higher levels of LAR activity than nontransformed plants. 

Wagner et al. 33) have shown that two distinct polysaccharide fractions from Echinacea purpurea exhibited pronounced activities characterized by a high rate of phagocytosis stimulation. One polysaccharide was shown to be a heteroxylan of molecular weight 35000 and an arabinorhamnogalactan of molecular weight 450000. The main characteristics of these polysaccharides from Echinacea were the optimal solubility in water, the high content of uronic acids, and the very complex structure. 

Lawrence, R. C. 1967. Microbial lipases and related esterases. Part II. Estimation of lipase activity. Characterization of lipases. Recent work concerning their effect on dairy products. Dairy Sci. Abstr. 29, 59-70. 

Rotaru, G. 1980. The milk clotting activity characterization of an enzymatic preparation from Aspergillus niger. Bull. Univ. Galati Technol. Chimia Produselor Aliment. 3, 43-48. 

The macrolide antibiotics provide us with excellent examples of natural products conforming to the acetate pathway, but composed principally of propionate units, or mixtures of propionate and acetate units. The macrolides are a large family of compounds, many with antibiotic activity, characterized by a macrocyclic lactone ring, typically 12, 14, or 16 membered, reflecting the number of units utilized. Zear-alenone (Figure 3.59), a toxin produced by the... 

The second phase of ecological risk assessment, the analysis phase, includes two principal activities characterization of exposure and characterization of ecological effects (Figure 28.1). 

Quantitation Once protein expression profiling activities characterize qualitative features, the attention turns to delineating protein interactions and mechanistic pathways responsible for disease. These studies also require rapid sequence determination/confirmation combined with accurate and sensitive quantitative analysis. The quantitation approaches would allow for direct comparison of protein amounts (absolute or relative) from a variety of cellular states. Because of the reasons stated previously, quantitative applications are likely to be less dependent on 2-DGE and rely primarily on formats that involve specific purification and/or chromatographic separation with mass spectrometry. 

The field of particle size distribution analysis has experienced a renaissance over the past five years and is now a rapidly growing and lively area of scientific and technological activity. This revitalization has been driven by advances in electronics and computer technology in conjunction with the market pull for particle size distribution analysis methods that cover a wide dynamic particle size range and have improved resolution. These technological advances are embodied in computer-aided, user-friendly, reliable, and cost-effective instrumentation. Three activities characterize this renaissance. 

These results agree remarkably well with recent calculation235. It was proposed that at kinetic energies > 0.4 eV a different mechanism is being activated, characterized by nucleophilic attack at Cl rather than at C to give a [Me Cl2] intermediate complex in which the two chlorine atoms have become equivalent235. 

The paraffins dehydrogenation on platinum-alumina catalysts proceeds with constant rate up to some time-on-stream after which a slow deactivation of the catalysts takes place Since relative changes of the catalyst activity ( characterized by reaction rate) are proportional to relative amounts of the deposited coke it can suppose that coke formation is the main reason of deactivation. Deactivation can be related with an attainment of a threshold in coke concentration (Co) on catalysts. The threshold amounts are 1.8 wt.% for A-I, 6,8% and 2.2% for A-II and A-IXI catalysts respectively. The isobutane dehydrogenation in non-stationary region (C > Co) is described by the following kinetic equation ... 

Cockerill (4) prepared protein tyrosine kinase inhibitors consisting of anilinoquinazoline derivatives, (IV), to regulate aberrant protein tyrosine kinase activity characterized by overexpression or mutation resulting in uncontrolled cell growth. 

Berman cl, Yeo EL, Wencel-Drake JD, Furie BC, Ginsberg MH, Furie B. a platelet alphagranuie membrane protein Ih is associated with the plasma membrane after activation characterization and subcellular localization ofidateletacdvation-dependera granule-external membrane proteia7C/in/nvest 78 130-137,1986. 

Garcia-Domenech, R. and De Julidn-Ortiz, V. (1998). Antimicrobial Activity Characterization in a Heterogeneous Group of Compounds. J.Chem.Inf.Comput.Sci., 38,445- 9. 

Morphine (0.66 mg/kg i.m.) alone stimulates motor activity, characterized by muscle tremors and restlessness from 1 to 3 h after administration (Kalpravidh et al 1984). Morphine increases arterial blood pressure, heart rate and respiratory rate in ponies for up to 4 h (Kalpravidh et al 1984). The cardiopulmonary response to morphine (0.12-0.66 mg/kg) administered i.v. with xylazine (0.66 mg/kg) is characterized by quiet standing, decreased heart rate, cardiac output and respiratory rate and increased arterial blood pressure (Muir et al 1979). In the same study. 

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