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Topic: Chemical specificity

In the News (Thu 31 May 12)

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	Relationships Among Plants, Insect Herbivores, Pathogens, Parasitoids, and Secondary Metabolites
		Specific chemical pathways have been shown to be induced in plants as a result of insect herbivore feeding or attack by pathogens (1).
		Chemical labeling experiments established that the systemic volatiles are synthesized at the site of release, suggesting that a mobile chemical messenger is transported from the damage location to distal, undamaged leaves to trigger synthesis and volatile release.
		Chemical labeling studies have established that the compounds released in much greater quantities during the day and specifically in response to insect damage are synthesized de novo and are not stored in the plant, therefore showing to be the volatiles that are herbivore-induced.
	www.colostate.edu /Depts/Entomology/courses/en570/papers_2000/mannix.html (3667 words)

	Chemical specificity - Wikipedia, the free encyclopedia
		Chemical specificity is the ability of a protein's binding site to bind specific ligands.
		The fewer ligands a protein can bind, the greater its specificity.
		This page was last modified 15:37, 8 December 2005.
	en.wikipedia.org /wiki/Chemical_specificity (57 words)

	oe magazine - chemical imaging comes of age (Site not responding. Last check: 2007-11-01)
		Before the introduction of technologies like the CCD camera and electronically tunable wavelength filters that ushered in the age of chemical imaging, optical spectroscopy was an immensely important technique that had established itself as a premier analytical tool for determining sample composition and concentration.
		Recording specific spectral features such as band shape or peak height as a function of the sampling position can be used to construct chemical maps of the sample heterogeneity.
		Chemical images of the Pap samples are collected using an optical microscope that is coupled to a Fourier transform visible step-scan Sagnac interferometer and CCD detector.
	oemagazine.com /fromTheMagazine/may02/raman.html (2291 words)

	Specificity (Site not responding. Last check: 2007-11-01)
		Chemical catalysts display only limited selectivity, whereas enzymes show three levels of specificity: for the reactants, for the susceptible bond involved in the reaction, and the type of product produced.
		A useful advantage of enzyme specificity is that in a number of cases it extends to selective discrimination between stereoisomers of a substrate molecule.
		Specificity is an inherent feature of enzyme catalysis because the reaction takes in a particular region of the enzyme that is designed to accommodate the specific participants involved in the reaction.
	www-biol.paisley.ac.uk /Courses/StFunMac/glossary/specificity.html (585 words)

	Miniature Spectrometers for Chemical Detection
		Solving this sensor vs instrument dilemma is important because rapid on-site analysis is increasingly needed, and analytical chemical detection requires both chemical specificity and sensitivity-the ability to detect a specific chemical in trace amounts with the sensitivity of the human nose (part-per-million to part-per-billion levels).
		Recently developed chemical sensor technologies that look for simple, single-parameter changes-such as resonance frequency changes in quartz-crystal microbalances, swelling in polymers, refraction index changes in optical fibers, and bending in microcantilevers-might have the required sensitivity for a given application; however, because they typically lack chemical specificity, they often provide dubious data.
		The chemical detector surfaces can then be regenerated for repeat analysis by resistive heating of the detector elements to desorb the deposited chemicals.
	www.ornl.gov /info/ornlreview/measure/analy/minia/mini.htm (2611 words)

	SEMINAR/STUDY TOUR IN THE U.S.S.R. ON GENETIC SELECTION AND HYBRIDIZATION OF CULTIVATED FISHES
		Moreover, genes, in all probability, determine the relatively different chemical composition of the cell nucleus, the amount of water and oxygen in the cell, the colloid state of the karyoplasm, etc., that is, the genotype determines the nature of the secondary processes during irradiation.
		It should be mentioned that the study of the specificity in the reaction of definite loci to various mutagens is hindered by a series of modifying factors.
		For example, in plants the specificity of the effect of chemical mutagens can depend on the kind of plant, the mutagen dose, the length of its action and the conditions of cultivation of the first and subsequent generations.
	www.fao.org /docrep/005/B3310E/B3310E06.htm (5428 words)

	Binding site - Wikipedia, the free encyclopedia
		In biochemistry, a binding site is a region on a protein, DNA, or RNA to which specific other molecules and ions — in this context collectively called ligands, or more specifically, protein ligands — form a chemical bond.
		Binding sites also exhibit chemical specificity, a measure of the types of ligands that will bond, and affinity, which is a measure of the strength of the chemical bond.
		A more specific type of binding site is the transcription factor binding site, present on DNA.
	en.wikipedia.org /wiki/Binding_site (157 words)

	'Dog-on-a-chip' could replace drug-sniffing canines
		Specificity is the ability to differentiate a certain chemical from a group of many similar ones (e.g., cocaine from coffee grounds).
		This sensitivity is achieved through surface acoustic wave (SAW) electronics, a method of detecting a chemical by measuring the disturbance it causes in sound waves across a tiny quartz crystal.
		The ability to detect and identify small, non-volatile molecules like cocaine based on their electronic vapor signature could also be used in airports and other locations to detect explosives and chemical warfare agents, according to the researchers.
	www.eurekalert.org /pub_releases/2003-10/acs-cr102903.php (739 words)

	NRL - Carbon Nanotube Networks: A New Electronic Material
		Chemical Detection: Because they are composed entirely of surface atoms, the electrical resistance of SWNTs is extremely sensitive to the physisorption of certain chemical vapors.
		At NRL we have performed preliminary experiments to test the viability of CNN chemical detectors, with a focus on achieving high levels of sensitivity and chemical specificity.
		Future work includes improving the transistor performance by using chemical separation techniques to purify SWNTs based on electronic type, chemical functionalization of the SWNTs to further enhance the sensitivity and chemical specificity of the sensors, and exploring additional CNN applications such as biosensing.
	www.nrl.navy.mil /content.php?P=04REVIEW160 (956 words)

	Chemical & Engineering News: Latest News - Zeroing In On Active Catalytic Sites
		Researchers at the University of California, Riverside, have developed a procedure that identifies the nature of the sites to which specific reagent molecules bond and the selectivity of that process-key steps in understanding reaction mechanisms.
		Understanding the nature of the active sites that drive certain chemical transformations is an important but often elusive goal in catalytic studies, says Daniel R. Strongin, a chemistry professor at Temple University, Philadelphia, and a specialist in surface science.
		He adds that the methodology is general enough to have the potential to be applicable to many chemically important systems.
	pubs.acs.org /cen/news/84/i24/8424notw8.html (471 words)

	Charting chemical space: finding new tools to explore biology
		And if we look at the exploitation of the various chemical elements by biological systems, we see that in general biology has selected, and is now dependent on, those elements that are abundant in the Earth's crust.
		Chemical space can be thought of as consisting of vast numbers of synthetic small molecules with diverse templates, functionalities, chirality and biological properties.
		Thus, principles are being developed to generate ligands that elicit tailored and specific cellular responses through their ability to stabilize or destabilize specific protein complexes.
	www.nature.com /horizon/chemicalspace/sessionsummaries.html (2841 words)

	Chemical Drug Delivery Systems: Strategies And Applications - Technology Trendz - Express Pharma Pulse
		Chemical drug delivery systems and prodrugs are designed to target specific enzymes or carriers by considering enzyme-substrate specificity or carrier-substrate specificity in order to overcome various undesirable drug properties.
		Chemical delivery systems are also designed for b-blocking agents used in the treatment of glaucoma.
		Soft analogs are close structural analogs of known active drugs that have a specific metabolically sensitive moiety built into their structure to allow facile, one-step controllable deactivation and detoxication after the desired therapeutic activity is achieved.
	www.expresspharmapulse.com /20050818/technologytrendz01.shtml (1498 words)

	Timothy Lezon: Research (Site not responding. Last check: 2007-11-01)
		Each protein acts as a molecular machine that performs a very specific chemical task, and the various proteins within a cell work together in an orchestrated manner to sustain the chemical processes necessary for life.
		Even though the proteins exhibit remarkable chemical diversity, they are all simply linear chain molecules, the monomers of which are the 20 amino acids coded by the DNA.
		Under its natural physiological conditions, each protein adopts a distinct native state fold which, along with the chemical properties of the protein's constituent amino acids, endows the protein with the chemical specificity and sensitivity required for proper function.
	www.phys.psu.edu /~lezon (364 words)

	Rescue of Vasopressin V2 Receptor Mutants by Chemical Chaperones: Specificity and Mechanism -- Robben et al. 17 (1): ...
		Chemical Chaperones Induce Translocation of V2R-V206D to the Plasma Membrane
		Rescue of V2R mutants by pharmacological and chemical chaperones.
		Welch, W. J., and Brown, C. Influence of molecular and chemical chaperones on protein folding.
	www.molbiolcell.org /cgi/content/full/17/1/379 (4982 words)

	EPSIS - Electroconductive Polymer Sensor Interrogation System
		The chemical specificity of chemical sensors may be derived form the use of various indicator agents including: macrocyclic agents and other inorganic binding compounds, metal occlusions, and inorganic catalysts.
		The biological specificity of biosensor devices may be conferred by the use of immobilized co-factors, enzymes, antibodies, enzyme-antibody conjugates, stabilized receptors, and DNA fragments.
		The resulting electrical conductivity of these chemically sensitive polymers (under controlled circumstances) is precisely governed by the state of charge or extent of oxidation/reduction of the polymer.
	www.abtechsci.com /epsis.html (819 words)

	Magnetic Resonance Force Microscopy
		Magnetic resonance force microscopy (MRFM) is a scanned probe technique that combines the chemical specificity capabilities of magnetic resonance with the high sensitivity and resolution capabilities of atomic force microscopy.
		MRFM is a non-destructive technique capable of imaging three-dimensional subsurface entities of a broad range of materials with chemical specificity and the potential for achieving atomic-scale resolution.
		Mechanically-detected (or force-detected) magnetic resonance microscopy (as sometimes MRFM is called) detects magnetic resonance signals by measuring the force F = (m • ∇)B between the spin magnetization m of a specimen undergoing magnetic resonance and the field gradient ∇B produced by a small magnet.
	www.jhuapl.edu /areas/sciencetech/SensorTechnology/MRFM.asp (373 words)

	[No title]
		Active participation by scientists and engineers in the chemical, pharmaceutical, agrichemical, electronics, and energy industries dependent on chemistry-based manufacturing is required.
		Although the U.S. position in the world economy is enhanced enormously by the positive trade balance enjoyed by the chemical and allied industries, chemicals that go up the stacks and down the drains are both a serious detriment to the environment and a waste of valuable natural resources.
		Contributions of the research to the education of future chemists and chemical engineers with improved expertise in the environmental issues of chemical process and product design are also important.
	www.ibiblio.org /pub/docs/nih-nsf/chemical.920320 (2458 words)

	Targeted Prodrug Design to Optimize Drug Delivery (Site not responding. Last check: 2007-11-01)
		The prodrug approach, a chemical approach using reversible derivatives, can be useful in the optimization of the clinical application of a drug.
		to signify pharmacologically inactive chemical derivatives that could be used to alter the physicochemical properties of drugs, in a temporary manner, to increase their usefulness and/or to decrease associated toxicity.
		Thus, in terms of specificity, enzymes from nonhuman sources, particularly those of microbiological origin, are advantageous, and if their immunogenicity is controllable, then specificity may become the overriding consideration
	www.aapsj.org /view.asp?art=ps020106 (4711 words)

	Voet Chapter 12 Summary Notes: Introduction to Enzymes
		Note to self: This suggests a parametric scale of 0.0 to 1.0, with 0.0 being lock and key and 1.0 being induced fit, being a useful way to characterize the position that enzymes occupy in the spectrum between these two models.
		Enzymes are selective about the identities of the chemical groups on their substrates.
		Geometric specificity is a more stringent requirement than is stereospecificity.
	www.wdv.com /CellWorld/Biochemistry/BioChem5104/VoetNotes12.html (711 words)

	PROGRAMS AND PLANS--Immunoassay Field Screening Tests for Pesticides
		However, most of the commercial pesticide immunoassay tests are based on polyclonal antibodies and, therefore, exhibit chemical specificity for families of compounds instead of individual compounds (i.e., triazine herbicides rather than atrazine only).
		The primary function of the tests is to provide a qualitative to semiquantitative screening to detect the presence or absence of a targeted chemical or chemical family.
		Although each test is designed to be most sensitive to a particular chemical, it has some level of sensitivity to the whole family of chemicals and their metabolites.
	water.usgs.gov /admin/memo/QW/qw92.09.html (1763 words)

	Xie Group CARS
		Optical microscopy is unique among current imaging modalities in its ability to probe living specimens with subcellular resolution, enabling the visualization of morphological details in tissue and cells on the scale of a few hundred nanometers.
		The contrast in confocal reflectance microscopy and optical coherence tomography (OCT), for instance, is based on refractive index differences, and cannot directly probe the chemical composition of tissue structures.
		Fluorescence microscopy, while extremely sensitive and widely used, is limited in chemical selectivity by the small number of intrinsic fluorophores, such as NAD(P)H, riboflavins and elastin.
	bernstein.harvard.edu /research/cars-why.htm (796 words)

	In Situ Reaction Monitoring
		Raman spectroscopy provides the chemical specificity of a mid-IR analyzer with the ease of sampling of a near-IR analyzer.
		Advanced calibration protocols permit chemical models developed in the laboratory to be easily transferred to pilot or production reactors.
		Progesterone is both an important active agent and chemical intermediate in the pharmaceutical industry.
	www.kosi.com /raman/analyzers/ramanrxn1.html (608 words)

	Lawrence C. Katz
		Recordings of brain activity, in conjunction with sophisticated chemical analytical techniques, have enabled us to uncover the special smells used by animals to communicate their identity and sex to other members of their species.
		A synthetic version of this chemical makes urine more attractive to female mice, providing a direct link between the chemical specificity of a group of neurons and behavioral output.
		Thus, the output from the bulb appears to convey highly specific information about the nature of the olfactory stimulus, resembling the “labeled lines‿ that have been observed in coding of chemical stimuli in the taste system (see the abstract of Charles Zuker [HHMI, University of California, San Diego]).
	www.hhmi.org /research/investigators/katz.html (1378 words)

	The Antibody Resource Page \| antibody
		By taking advantage of the varied chemical properties of the 20 amino acids, the immune system is able to generate an array of antibody binding pockets that can accommodate the shape, charge, and hydrophobicity of seemingly any given antigen.
		While commonplace today, the use of chemical methodologies to understand immunological phenomena early on in the field of immunochemistry was considered a revolutionary approach.
		I have given to these lectures the title "Immuno-chemistry" and wish with this word to indicate that the chemical reactions of the substances that are produced by the injection of foreign substances into the blood of animals, i.e.
	www.antibodyresource.com /antibody.html (4912 words)

	Enzyme Concentrate Manufacturer,Textile Auxiliaries Manufacturer,Enzyme Concentrate Suppliers,Textile Auxiliaries ...
		A few enzymes will be specific for a particular type of chemical bond or functional group.
		Group specificity-the enzyme will act only on molecules that have specific function groups, such as amino, phosphate and methyl groups.
		Linkage specificity - the enzyme will act on a particular type of chemical bond regardless of the rest of the molecular structure.
	www.textiles-chemicals.com /enzyme-concentrate.html (348 words)

	New chemical instrument uses advanced missile technology
		It is nearly 5,000 times faster than other technology in screening samples of catalysts that react with liquids, and at least 20 times faster in screening catalysts that react with gas, such as those used in catalytic converters for automotive exhaust systems and in numerous manufacturing processes.
		This technique combines the chemical specificity and high sensitivity of FTIR with the ability to rapidly analyze multiple supported resin beads simultaneously.
		It is shown here that the chemical identify of ligands on a variety of supported resin beads can be identified in a single experiment without destroying or otherwise perturbing the system.
	news.uns.purdue.edu /html4ever/0006.Lauterbach.catalysts.html (948 words)

	Army Technology - Microsensor Systems - Trace Chemical Detection Through Surface Acoustic Wave Sensing (Site not responding. Last check: 2007-11-01)
		MSI provides instruments and sensors for the detection of nerve and blister Chemical Warfare Agents (CWA), blood and choking agents as well as several other classes of Toxic Industrial Chemicals (TIC) that may be used in chemical warfare, terrorist incidents or hazardous material spills.
		False positives alarms from fuels, cleaning solvents and other common chemicals are eliminated, decreasing the amount of training necessary to become competent with equipment.
		Specifically, the presence of blood agents (Hydrogen Cyanide/AC), choking agents (Phosgene/CG), hydride gases and halogens gases can be quickly identified, providing the user the ability to screen for a broad spectrum of potential threats.
	www.army-technology.com /contractors/nbc/microsensor_systems/index.html (800 words)

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