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Topic: Enzyme catalysis

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	Botany online: Physical Chemistry - Mechanisms of Enzyme Catalysis
		Enzyme molecules are, compared to most of their substrate molecules, rather large.
		Often, the enzyme's surface is structured in a way that the coenzyme is bound to a specifically shaped pocket.
		At a constant enzyme concentration, the turn-over velocity (v) of an enzyme increases as a function of the substrate concentration.
	www.biologie.uni-hamburg.de /b-online/e18/18d.htm (976 words)

	Enzyme - Wikipedia, the free encyclopedia
		To name different enzymes, one typically uses the ending -ase with the name of the chemical being transformed (substrate), e.g., lactase is the enzyme that catalyzes the cleavage of lactose.
		Enzymes are usually specific as to the reactions they catalyze and the substrates that are involved in these reactions.
		Enzymes are very specific and it was suggested by Emil Fischer in 1890 that this was because the enzyme had a particular shape into which the substrate(s) fit exactly.
	en.wikipedia.org /wiki/Enzyme (3549 words)

	Enzyme Catalysis
		Enzymes are biological macromolecules that catalyze chemical reactions.
		First, enzymes show high specificities toward their physiological substrates; compounds that differ only slightly from the natural substrate are often not acted upon.
		For example, the induced fit hypothesis postulates that the conformation of the enzyme changes during the substrate binding process such that interactions between the enzyme and the substrate are optimized.
	www.chem.ucsb.edu /~kalju/catalysis.html (565 words)

	Enzyme catalysis, kinetics, and allostery
		The specificity of an enzyme is therefore a measure of the specificity of an enzyme for competing substrates or of competing enzymes for a single substrate.
		The enzyme is activated by the proteolytic removal of two di-peptides at positions 14-15 and 147-148.
		Its 'enzyme' activity is not the catalysis of a reaction, but to increase the water solubility of oxygen and to facilitate its transport to the muscle cell.
	www.whatislife.com /reader/enzyme/enzyme.html (3420 words)

	Chemical Sciences: Enzyme Catalysis
		Enzymes are normally named after the reactions they catalyze because their molecular structure is very complex and in many cases unknown.
		For example, superoxide dismutase is the enzyme responsible for the destruction of the superoxide ion in living organisms.
		In some reactions catalyzed by enzymes, the reaction appears to take place on the surface of the catalyst enzyme molecules themselves, which may or may not be in homogeneous solution.
	www.psigate.ac.uk /newsite/reference/plambeck/chem2/p02175.htm (854 words)

	Computational Methods for Enzyme Catalysis
		Enzymes have many potential uses in chemical technology, but naturally occurring enzymes may have to be modified in order to effect the desired reactivity.
		However, examination of the structures of typical enzymes and their complexes with other molecules reveals that typically only a small portion of the enzyme is actually in contact with the reactants or potentially involved in the reaction.
		The enzyme is bovine pancreatic ribonuclease A (RNase) which is one of the most widely studied enzymes for the past forty years.
	math.nist.gov /hpcc/cstl/proj-1.html (632 words)

	BC Online: 7D - Enzyme Catalysis in Organic Solvent
		Enzyme in anhydrous organic solvents are so useful (from a synthetic point) not only since new types of reactions can be catalyzed (such as transesterification, ammonolysis, thiolysis) but also because the stereoselectivity, regioselectivity, and chemoselectivity of the enzyme often changes from activities of the enzyme in water.
		In a manner analogous to using an enzyme as a heterogeneous catalyst in nonpolar solvent, Sharpless is pioneering a technique to conduct organic reactions in water.
		As in enzyme catalysis in nonpolar solvent, the reactions must be mixed vigorously to disperse reactants in micro-drops (a suspension) in water, greatly increasing the surface area that might allow water to act on transition states or intermediates to stabilize them through hydrogen bonding.
	employees.csbsju.edu /hjakubowski/classes/ch331/catalysis/olcatorgsolv.html (1378 words)

	Is the Brain a Catalyst (Site not responding. Last check: )
		In the case of catalysis, the action of the soliton is to provide sufficient energy via conformation changes to cause the wave functions of the substrate and products to overlap and thereby increase the likelihood of quantum tunneling at the transition state.
		At the level of the enzyme we observe highly specific instances of catalysis whereas, at the level of the cell, we observe a continuous and non-specific catalytic phenomenon.
		Also, because the process of enzyme catalysis, and catalysis more generally, appears to involve oscillatory waves, the proposal is consistent with the considerable evidence and arguments that have implicated resonance in perception and neuroscience (e.g., Shepard, 1984; John, 2000).
	www.pitt.edu /~cogtalks/davia102.html (997 words)

	ap sample lab 2 catalysis3 (Site not responding. Last check: )
		Catalysis is a substance that lowers reaction energy and allows the reaction to take place in less time and at lower temperatures.
		Most enzymes denaturalize around 40-50°C. The law of mass action states the direction of enzyme-catalyzed reaction is dependent on conservation of enzyme/substrate/product.
		The boiled catalysis was not as reactive as the regular catalysis, because boiling the catalysis denatures it.
	sps.k12.ar.us /massengale/ap_sample_lab_2_catalysis3.htm (1741 words)

	The mechanism of enzyme catalysis
		All catalysts, including enzymes, function by forming a transition state, with the reactants, of lower free energy than would be found in the uncatalysed reaction (Figure 1.1).
		The most important of these involves the enzyme initially binding the substrate(s), in the correct orientation to react, close to the catalytic groups on the active enzyme complex and any other substrates.
		The energies available to enzymes for binding their substrates are determined primarily by the complementarity of structures (i.e.
	www.lsbu.ac.uk /biology/enztech/mechan.html (704 words)

	Age-related effects in enzyme catalysis. (Site not responding. Last check: )
		While the amount of this enzyme in muscle tissue does not change with age, both its specific activity and affinity towards its co-enzyme are significantly reduced in the old tissue.
		Age-related structural changes were found to exist in the nicotinamide binding site of the enzyme and the reactions leading to the activity loss in 'old' glyceraldehyde-3-phosphate dehydrogenase were shown to involve a reversible modification of the essential cysteine-149 residue at the active site of the enzyme.
		The enzyme modified in this way closely resembles native 'old' glyceraldehyde-3-phosphate dehydrogenase, indicating that the structural modifications in the latter enzyme are indeed introduced by a post-translational process.
	www.arclab.org /medlineupdates/abstract_6369109.html (211 words)

	Enzyme (Site not responding. Last check: )
		An enzyme can be a large protein made up of several hundred amino acids, or several proteins that act together as a unit.
		Enzymes can couple two or more reactions, so that a thermodynamically favourable reaction can be used to "drive" a thermodynamically unfavorable one.
		Enzymes are essential to living organisms, and a malfunction of even a single enzyme out of approximately 2,000 present in our bodies can lead to severe or lethal illness.
	www.yotor.com /wiki/en/en/Enzyme.htm (1499 words)

	mclect7
		Enzymes catalyze reactions by providing a template upon which a substrate can reside, be distorted into a reaction shape, and coerced into bond-braking or bond-forming reactions.
		Enzymes are incredibly specific, meaning, their catalytic action is highly dependent upon a certain complementarity between the enzyme active site (business section) and the substrate.
		Usually general acid catalysis or general base catalysis is operative, however, both mechanisms may "gang up" on a substrate to induce the catalysis.
	www.umt.edu /medchem/teaching/medchem/mclect7.htm (2292 words)

	Floating Ball Analogies for Enzyme Catalysis
		(A) A barrier dam is lowered to represent enzyme catalysis.
		The green ball represents a potential enzyme substrate (compound X) that is bouncing up and down in energy level due to constant encounters with waves (an analogy for the thermal bombardment of the substrate with the surrounding water molecules).
		In the right-hand box, enzyme catalysis lowers the activation energy for reaction number 1 only; now the jostling of the waves allows passage of the molecule over this energy barrier only, inducing reaction 1.
	www.accessexcellence.org /RC/VL/GG/enzyme_Cat.html (229 words)

	enzymekinetics info window
		The interactions between enzymes and substrates are often difficult to understand and the model allows users to visualize the complex reaction.
		Enzyme catalysis is often assumed to be controlled by the rate of complex formation and dissociation, because it occurs much faster than the rate of catalysis.
		Enzyme catalysis can also be controlled using inhibitors.
	ccl.northwestern.edu /cm/models/enzymekinetics/info.html (964 words)

	ECC 1989 - Cyclic Process of Enzyme Catalysis - Page 4 of 18 - JWLABS
		An enzyme catalytic process is a cyclic reaction because the enzyme is recycled at each turnover.
		Again, the reaction is driven by the negative free energy of the S to P conversion, although the description of the process is inherently unidirectional since it is shown to proceed only in the clockwise direction.
		To be more precise, the enzyme state which favors the binding substrate must be different from the state which favors the binding of the product state.
	www.jwlabs.com /ecc4.htm (441 words)

	untitled
		Enzymes are proteins that act as biological catalysts within the cells of all living organisms.
		Enzymes are very specific in the types of reactions in which they will participate.
		Summarize the reaction of the enzyme and the substrate:
	www.bhs.jordan.k12.ut.us /~science/Enzyme.htm (896 words)

	Bioc 462a Lecture Notes
		It's possible that the substrate and enzyme interact unfavorably and this unfavorable interaction is relieved in the transition state.
		Binding substrate to enzyme may stabilize a different conformation of either the enzyme or the substrate, orienting catalytic groups on the enzyme or promoting tighter transition state binding, and/or excluding water.
		The enzyme molecule is now in its original state, with the His imidazole in its neutral form, the catalytic triad appropriately hydrogen-bonded, and the active site ready to bind another molecule of substrate and do it all again.
	www.biochem.arizona.edu /classes/bioc462/462a/NOTES/ENZYMES/enzyme_mechanism.html (5949 words)

	AP Lab Two/Enzyme Catalysis
		Note that the enzyme is not changed in the reaction and can even be recycled to break down additional substrate molecules.
		Each enzyme is specific for a particular reaction because its amino acid sequence is unique and causes it top have a unique three-dimensional structure.
		Since enzymes are catalysts for chemical reactions, enzyme reactions also tend to go faster with increase temperature.
	www.ekcsk12.org /science/aplabreview/aplabtwoenzymecatalysis.htm (1304 words)

	ScienceWeek
		The catalysis of many proton-transfer reactions, for example, requires the recognition of a change in a CH bond length of about 0.5 in going from the reactant to the transition state.
		An increasing number of articles propose a variety of origins for enzyme catalysis described by terms such as correlated conformational fluctuations, dynamical and nonequilibrium effects, electrostatic pre-organization, entropic guidance, fluctuating barrier height, near-attack configurations, reactant destabilization, and tunneling.
		The thesis of the present article is that modern simulations of transition states are a powerful tool for discovering these mechanisms and that all such mechanisms can be understood in terms of various contributions to a specific equation from transition state theory relating the rate constant for a reaction as a function of the temperature.
	scienceweek.com /2004/sa040227-4.htm (1426 words)

	enzyme purification and analysis
		Our expertise in protein purification and characterization is based on an over ten year scientific experience with enzymes of proteolysis and cell energy metabolism.
		Recombinant enzymes are compared with the natural forms to examine their physiological function.
		gentle enzyme purification to homogeneity, preserving the native structure and function
	www.amplab.de /enzyme_analysis.htm (84 words)

	ScienceWeek
		The structure showed the transition state for glycoside cleavage to be stabilized by the enzyme: The strong electrostatic field of the two carboxylates contributed by Asp52 and Glu35 on either side of the active-site cleft are positioned to interact with the developing positive charge on the oxocarbenium ion.
		The authors have studied dynamics of an enzyme during catalysis at atomic resolution using nuclear magnetic resonance relaxation methods.
		During catalytic action of the enzyme cyclophilin A, the authors detect conformational fluctuations of the active site that occur on a time scale of hundreds of microseconds.
	scienceweek.com /2003/sc031024-4.htm (793 words)

Article 32- Enzyme Catalysis Without Water</a></td></tr> <tr><td valign=top><img style="margin-top:4px;" src=/images/a.gif></td><td></td><td> One of the fastest growing areas of industrial biotechnology is the use of <b>enzymes</b> in non-aqueous media. </td></tr> <tr><td valign=top><img style="margin-top:4px;" src=/images/a.gif></td><td></td><td> This counterintuitive behavior is explained by the fact that <b>enzymes</b> are in their most stable state in pure water. </td></tr> <tr><td valign=top><img style="margin-top:4px;" src=/images/a.gif></td><td></td><td> We were merely interested in watching an <b>enzyme</b> lose activity and had no inkling that the condition we thought would totally kill the <b>enzyme</b> would actually sustain it.</td></tr> <tr><td></td><td colspan=2><font color=gray>www.winstonbrill.com /bril001/html/article_index/articles/1-50/article32_body.html</font> (1204 words)</td></tr> </table> </td> </tr> </table><body face="Arial"> <br> <table cellpadding=0> <tr> <td> </td> <td> <table > <tr><td> </td><td colspan=2><u>ENZYME CATALYSIS</u> <i>(Site not responding. Last check: )</i></td></tr> <tr><td valign=top><img style="margin-top:4px;" src=/images/a.gif></td><td></td><td> The mechanisms by which <b>enzymes</b> catalyze reactions are of interest from a purely scientific, physical organic perspective, but also from an applied point of view: understanding an <b>enzyme</b> mechanism has implications for inhibitor design and potentially, rational drug design. </td></tr> <tr><td valign=top><img style="margin-top:4px;" src=/images/a.gif></td><td></td><td> The decarboxylation of OMP is catalyzed by a highly proficient <b>enzyme</b>, OMP decarboxylase; the mechanism remains unknown. </td></tr> <tr><td valign=top><img style="margin-top:4px;" src=/images/a.gif></td><td></td><td> Computational and experimental studies are used to uncover the mechanisms by which the <b>enzyme</b> can effect <b>catalysis</b>.</td></tr> <tr><td></td><td colspan=2><font color=gray>rutchem.rutgers.edu /faculty/lee/enzymecatalysis.html</font> (181 words)</td></tr> </table> </td> </tr> </table><body face="Arial"> <br> <table cellpadding=0> <tr> <td> </td> <td> <table > <tr><td> </td><td colspan=2><a href="http://www.chemistry.ucsc.edu/~fink/231/lecture2.htm">CHEMICAL CATALYSIS</a></td></tr> <tr><td valign=top><img style="margin-top:4px;" src=/images/a.gif></td><td></td><td> Perhaps not surprisingly, the mechanisms used by <b>enzymes</b> are those found in physical-organic chemistry of the substrate. </td></tr> <tr><td valign=top><img style="margin-top:4px;" src=/images/a.gif></td><td></td><td> The answer, which comes from the Bronsted <b>catalysis</b> law, is that the stronger the base, or acid, the better it will be as a general catalyst. </td></tr> <tr><td valign=top><img style="margin-top:4px;" src=/images/a.gif></td><td></td><td> The efficiency of general base <b>catalysis</b> increases with the base strength of the catalyst, the slope of a plot of log k2 (second-order rate constant) vs. pK gives a measure of the sensitivity of the reaction to the strength of the base.</td></tr> <tr><td></td><td colspan=2><font color=gray>www.chemistry.ucsc.edu /~fink/231/lecture2.htm</font> (927 words)</td></tr> </table> </td> </tr> </table><body face="Arial"> <br> <table cellpadding=0> <tr> <td> </td> <td> <table > <tr><td> </td><td colspan=2><u>Amazon.com: Catalysis in Chemistry and Enzymology: Books</u> <i>(Site not responding. Last check: )</i></td></tr> <tr><td valign=top><img style="margin-top:4px;" src=/images/a.gif></td><td></td><td> <b>Enzymes</b>: A Practical Introduction to Structure, Mechanism, and Data Analysis by Robert A. Copeland </td></tr> <tr><td valign=top><img style="margin-top:4px;" src=/images/a.gif></td><td></td><td> jencks' classic tome <b>"catalysis</b> in chemistry and enzymology" gives such insights into the mechanisms of <b>enzymes</b> which many people are still working with. </td></tr> <tr><td valign=top><img style="margin-top:4px;" src=/images/a.gif></td><td></td><td> what jencks clearly outlines are how the major forms of <b>enzyme</b> reactions work, what their mechanisms are, and how these reactions are catalyzed in terms of kinetics and thermodynamics.</td></tr> <tr><td></td><td colspan=2><font color=gray>www.amazon.com /exec/obidos/tg/detail/-/0486654605?v=glance</font> (755 words)</td></tr> </table> </td> </tr> </table><body face="Arial"> <br> <table cellpadding=0> <tr> <td> </td> <td> <table > <tr><td> </td><td colspan=2><u>Tailoring the pH dependence of enzyme catalysis using protein engineering</u> <i>(Site not responding. Last check: )</i></td></tr> <tr><td valign=top><img style="margin-top:4px;" src=/images/a.gif></td><td></td><td> Department of Chemistry, Imperial College of Science and Technology, London SW7 2AY, UK One of the goals of protein engineering is to tailor the pH dependence of <b>enzyme</b> <b>catalysis</b> to optimize activity in industrial processes. </td></tr> <tr><td valign=top><img style="margin-top:4px;" src=/images/a.gif></td><td></td><td> Electrostatic effects are of considerable importance in <b>enzyme</b> <b>catalysis</b> and are thought to play a major part in stabilizing charged transition states </td></tr> <tr><td valign=top><img style="margin-top:4px;" src=/images/a.gif></td><td></td><td> However, it is extremely difficult to calculate electrostatic effects in proteins because of the microheterogeneity of the dielectric constant.</td></tr> <tr><td></td><td colspan=2><font color=gray>www.nature.com /cgi-taf/DynaPage.taf?file=/nature/journal/v318/n6044/abs/318375a0.html</font> (421 words)</td></tr> </table> </td> </tr> </table><body face="Arial"> <br> <table cellpadding=0> <tr> <td> </td> <td> <table > <tr><td> </td><td colspan=2><a href="http://www.jbc.org/cgi/content/abstract/275/50/39200">The Role of alpha -Amino Group of the N-terminal Serine of beta Subunit for Enzyme Catalysis and Autoproteolytic ...</a></td></tr> <tr><td valign=top><img style="margin-top:4px;" src=/images/a.gif></td><td></td><td> The Role of alpha -Amino Group of the N-terminal Serine of beta Subunit for <b>Enzyme</b> <b>Catalysis</b> and Autoproteolytic Activation of Glutaryl 7-Aminocephalosporanic <a href="/topics/Acid" title="Acid" class=fl>Acid</a> Acylase -- Lee et al. </td></tr> <tr><td valign=top><img style="margin-top:4px;" src=/images/a.gif></td><td></td><td> Subunit for <b>Enzyme</b> <b>Catalysis</b> and Autoproteolytic Activation of Glutaryl 7-Aminocephalosporanic <a href="/topics/Acid" title="Acid" class=fl>Acid</a> Acylase </td></tr> <tr><td valign=top><img style="margin-top:4px;" src=/images/a.gif></td><td></td><td> <b>enzyme</b> <b>catalysis</b> and in the secondary cleavage of the <b>enzyme</b> precursor.</td></tr> <tr><td></td><td colspan=2><font color=gray>www.jbc.org /cgi/content/abstract/275/50/39200</font> (546 words)</td></tr> </table> </td> </tr> </table><body face="Arial"> <br> <table cellpadding=0> <tr> <td> </td> <td> <table > <tr><td> </td><td colspan=2><a href="http://www.pnas.org/cgi/content/short/75/11/5250">Energetics of Enzyme Catalysis -- Warshel 75 (11): 5250 -- Proceedings of the National Academy of Sciences</a></td></tr> <tr><td valign=top><img style="margin-top:4px;" src=/images/a.gif></td><td></td><td> Energetics of <b>Enzyme</b> <b>Catalysis</b> -- Warshel 75 (11): 5250 -- Proceedings of the National Academy of Sciences </td></tr> <tr><td valign=top><img style="margin-top:4px;" src=/images/a.gif></td><td></td><td> Quantitative studies of the energetics of enzymatic reactions and the corresponding reactions in aqueous solutions indicate that charge stabilization is the most important energy contribution in <b>enzyme</b> <b>catalysis</b>. </td></tr> <tr><td valign=top><img style="margin-top:4px;" src=/images/a.gif></td><td></td><td> This is established quantitatively by comparing the relative stabilization of the transition states of the reaction of lysozyme and the corresponding reaction in aqueous solution.</td></tr> <tr><td></td><td colspan=2><font color=gray>www.pnas.org /cgi/content/short/75/11/5250</font> (458 words)</td></tr> </table> </td> </tr> </table><script language="JavaScript">  </script> <script language="JavaScript">  </script> <script language="JavaScript" src="http://pagead2.googlesyndication.com/pagead/show_ads.js"> </script> <br> <p style="margin-left:30px;font-size:13px;"><b>Try your search on: <a href="http://www.qwika.com/find/Enzyme catalysis">Qwika</a> (all wikis)</b></p> <form action=http://www.factbites.com/search.php><table width="100%" cellspacing=0 cellpadding=0 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