Enzyme activity - Factbites

Enzyme activity - Factbites
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Topic: Enzyme activity

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	Enzyme - Wikipedia, the free encyclopedia
		An enzyme can, however, run a normally non-spontaneous reaction 'backwards' by coupling it to a spontaneous one, as long as the net free energy from the total of both reactions is negative.
		Like any catalyst, enzymes work by lowering the activation energy of a reaction, thus allowing the reaction to proceed to its steady state or completion much faster than it otherwise would; the enzyme (again, as with any catalyst) remains unaltered by the completed reaction and can therefore continue catalysis.
		Enzymes can perform up to several million catalytic reactions per second; to determine the maximum speed of an enzymatic reaction, the substrate concentration is increased until a constant rate of product formation is achieved.
	en.wikipedia.org /wiki/Enzyme

	Enzyme activity - Wikipedia, the free encyclopedia
		Molecular activity is expressed as molecules of substrate transformed per minute per molecule of enzyme.
		Enzyme activity is the catalytic effect exerted by an
		It is the amount of enzyme that will catalyze the transformation of one micromole of substrate per minute under standard conditions of temperature, pH and optimal substrate concentration.
	en.wikipedia.org /wiki/Enzyme_activity

	Amylase Lab Activity
		For instance you could study the effects of temperature on enzyme activity by placing three identically prepared plates in 3 temperature environments such as a refrigerator, an incubator and at room temperature.
		To determine the amount of starch digested by a given enzyme dilution it is necessary to determine the volume of the starch-agar clear zone.
		Each enzyme only catalyzes one kind of chemical reaction so there is a lot of enzymes in a typical cell.
	www.kabt.org /Labs/Amylase.htm

	Introduction to Enzyme Activity
		Enzymes are protein catalysts that influence the rate of a reaction.
		The formation of enzyme-substrate complexes is confined to relatively small areas of the enzyme molecule known as active sites, the precision with which an enzyme binds its substrate led to a rather stylized concept of the enzyme substrate complex which is based on the analogy of a lock and key.
		If the environment of the enzyme is too acidic or too basic, the enzyme may irreversibly denature, or unravel, until it no longer has the shape necessary for proper functioning.
	faculty.uca.edu /~march/bio1/enzymes/introenz.htm

	Characteristics of Enzymes
		Isomerases- Enzymes that catalyze the isomerization of molecules.
		Enzymes are the substances that allow life to exist at earth temperatures.
		Once the enzyme is inhibited the process cannot take place, and a toxicological symptom occurs that often leads to paralysis, coma or even death of the organism.
	members.aol.com /logan20/enzymes.html

	Myogenin Induces a Shift of Enzyme Activity from Glycolytic to Oxidative Metabolism in Muscles of Transgenic Mice -- Hughes et al. 145 (3): 633 -- The Journal of Cell Biology
		Enzyme activity in four wild-type soleus muscles was determined and divided by the mean value for each enzyme in the wild-type plantaris (Table I).
		Enzyme activity in plantaris, tibialis anterior, and soleus muscles from MMg transgenic mice was determined and divided by the mean value for each enzyme found in the same wild-type muscles (Table I).
		Enzyme activity in plantaris, tibialis anterior, and soleus muscles from MId transgenic mice (left) or in MMg + MId transgenic mice (right) was determined and divided by the mean value for each enzyme found in wild-type muscles (Table I).
	www.jcb.org /cgi/content/full/145/3/633

	BBC Education - AS Guru - Biology - Biological Molecules - Proteins - Enzymes
		Enzyme molecules have a complicated three-dimensional shape due to the particular way the amino acid chain that makes up the protein is folded.
		Once the enzyme and the substrate are joined they form an enzyme-substrate complex.
		Further research into enzymes has shown that the lock and key hypothesis, or model, does not always explain the whole story.
	www.bbc.co.uk /education/asguru/biology/02biologicalmolecules/01proteins/11enzymes/index.shtml

	Enzymes
		In either case, the chain is broken, the two fragments separate from the enzyme, and the enzyme is free to attach to a new location on the bacterial cell wall and continue its work of digesting it.
		Enzymes bind temporarily to one or more of the reactants of the reaction they catalyze.
		The enzyme is antibacterial because it degrades the polysaccharide that is found in the cell walls of many bacteria.
	users.rcn.com /jkimball.ma.ultranet/BiologyPages/E/Enzymes.html

	Effect of temperature and pH on enzyme activity
		Enzymes are usually quantified by their activity, not their concentration in terms of protein.
		The shape of the pH-activity curve is governed by the individual titration curves for the amino acid residues involved in substrate binding, catalysis and in maintaining an active conformation for the enzyme.
		This loss in activity may or may not be reversible on bringing the temperature back down to the optimum.
	www.fst.rdg.ac.uk /online/fs355/frame6.htm

	Influences on Enzyme Activity
		This allows the enzyme to respond to small changes in [substrate] because it is still on the steep part of the curve.
		As the concentration of the end-product increases, it exerts a negative feedback inhibition on an earlier enzyme in the pathway.
		Enzymes can also be inhibited by specific molecules, drugs, or poisons.
	www-rohan.sdsu.edu /~ens632/EnzymeKinetics.htm

	MedlinePlus Medical Encyclopedia: Enzyme markers
		Enzyme markers are tests for specific enzyme activity in the body.
		Results are reported as a percentage of typical (normal) enzyme activity.
		Diseases can cause enzymes to stop functioning or decrease their activity.
	www.nlm.nih.gov /medlineplus/ency/article/002354.htm

	Enzyme Activity in Alkaptonurics
		This enzyme converts homogentisic acid to maleylacetoacetic acid and a deficiency for this enzyme would allow for homogentisic acid to accumulate in cells and be excreted in the urine.
		He had suggested that the specific enzyme was involved in the degradation of homogentisic acid, an intermediate in the breakdown pathway of phenylalanine and tyrosine.
		It is clear that the enzyme activities for both types of individuals are virtually identical except for the enzyme homogenetisic oxidase.
	www.people.virginia.edu /~rjh9u/garrod.html

	Effects of pH
		As with activity, for each enzyme there is also a region of pH optimal stability.
		pH is also a factor in the stability of enzymes.
		Each of these physical and chemical parameters must be considered and optimized in order for an enzymatic reaction to be accurate and reproducible.
	www.worthington-biochem.com /introBiochem/effectspH.html

	Effect of temperature and pressure on enzyme activity
		A schematic diagram showing the effect of the temperature on the activity of an enzyme catalysed reaction.
		In this simple case, the half-life of the enzyme is shown to be inversely proportional to the rate of denaturation.
		These may have been formed during the past history of the enzyme during preparation and storage due to a number of minor reactions, such as deamidation of one or two asparagine or glutamine residues, limited proteolysis or disulphide interchange.
	www.lsbu.ac.uk /biology/enztech/temperature.html

	Activity Of Enzyme That Affects Mood Decreased In Brains Of Teenage Suicide Victims
		CHICAGO -- The activity of a brain enzyme known to affect mood may be decreased in teens who commit suicide, according to an article in the July issue of the Archives of General Psychiatry, one of the JAMA/Archives journals.
		Activity Of Enzyme That Affects Mood Decreased In Brains Of Teenage Suicide Victims
		The researchers found that protein kinase C activity was statistically significantly decreased in measurements in certain brain areas in teenage suicide victims' brains compared with measurements from the brains of control subjects.
	www.sciencedaily.com /releases/2004/07/040712083524.htm

	Enzyme units
		The activity is a measure of enzyme content that is clearly of major interest when the enzyme is to be used in a process.
		More relevant parameters are the activity of the enzyme preparation and the activities of any contaminating enzymes.
		These activities are usually measured in terms of the activity unit ( U) which is defined as the amount which will catalyse the transformation of 1 micromole of the substrate per minute under standard conditions.
	www.lsbu.ac.uk /biology/enztech/units.html

	Overexpression of a dominant-negative ornithine decarboxylase in mouse skin: effect on enzyme activity and papilloma formation -- Shantz et al. 23 (4): 657 -- Carcinogenesis
		a truncated ODC with wild-type activity ( 2, 3).
		ODC activity by expression of the ODC mutant, K69A/C360A.
		activity in spite of the presence of the ODCdn transgene.
	carcin.oupjournals.org /cgi/content/full/23/4/657

	GOT Enzyme Activity Assay
		To assay the activity of GOT we will use a different type of enzyme assay from that used in Expt #2 to assay the phosphatase, which was an end-point type of assay.
		I will discuss in the next lecture how we will convert the A-340 changes with time or absorbance rates for GOT to enzyme activity measured in terms of µmol OAA produced per min.
		This allows you to measure the activity of GOT since its activity level will limit the supply of OAA for the MDH activity.
	www.bio.mtu.edu /campbell/gotw43.htm

	Enzyme activity essays
		Enzyme Activity Aim: To investigate enzyme activity by testing for changes in a starch solution when the enzyme amylase is added and how this reaction is affected by heat, pH, ratios etc. Background of Enzymes Enzymes are biological catalysts produced by living cells.
		Enzymes themselves are made of protein and each one has a differently shaped active site, where the reaction takes place.
		A single cell may contain 100,000 different enzymes, which are needed to take part in its 1,000 to 2,000 chemical reactions.
	www.megaessays.com /viewpaper.php?request=4680

	Researchers First To Directly Increase Enzyme’s Activity
		However, in the reaction that transforms the organic matter into fuel, the low activity of the enzyme cellulase acts as a bottleneck, slowing the whole procedure down.
		The resulting mutant increased the enzyme’s activity by 13 percent.
		Sakon’s group increased the enzyme’s activity by 13 percent.
	www.sciencedaily.com /releases/1999/03/990323050251.htm

	Residues 190-210 of human topoisomerase I are required for enzyme activity in vivo but not in vitro -- Christensen et al. 31 (24): 7255 -- Nucleic Acids Research
		a crucial role for the activity of the enzyme in its physiological
		Residues 190-210 of human topoisomerase I are required for enzyme activity in vivo but not in vitro -- Christensen et al.
		the enzyme lacking this region is indicated by a lesser cytotoxicity.
	nar.oupjournals.org /cgi/content/abstract/31/24/7255

	Understanding Digestion, Assimilation And Enzyme Nutrition
		Exogenous plant enzymes are active in the pH range of 1.0 to 11.0 and can facilitate the utilization of a much larger amounts of protein, carbohydrates and fat before HCL is secreted in sufficient amounts to neutralize their activity.
		Food enzymes are essentially destroyed at 118 degrees Fahrenheit, thus most modern methods of food preparation leave food devoid of digestive enzyme activity.
		By continuing to be on enzyme therapy, which insured proper assimilation of her food, the progression of undigested foods in her body has been halted.
	www.extremehealthusa.com /digestive.html

	Chromogenic Substrates University IU and Enzyme Activity
		The enzyme activity expressed as katal is related to the type of substrate, to the nature of the enzyme and to the experimental conditions.
		In the following paragraphs, a tentative correlation between the different types of units and the enzyme activity with Chromogenix substrates is reported.
		The conversion factors, have been taken from journal articles or from laboratory results within the Chromogenix RandD department, thus the consultation of such references or of the assay conditions reported in the kinetic tables is recommended.
	www.chromogenicsubstrates.com /tech/chromogenic_substrates_iu.htm

	The Measurement of Enzyme Activity
		As a catalyst, though, the enzyme is independent of the reaction that it catalyzes; the enzyme itself does not appear as a substrate or product of the reaction on which it operates.
		The introduction of the enzyme begins the process of hydrolysis upon the sucrose, and the exact time at which the invertase was added was recorded.
		To test the linear nature of the enzyme mechanism, an analog of derivation is needed because of the experimental data's discrete nature.
	www.trinity.edu /slibs/enzymelab

	THE EFFECT OF HANDS-ON HEALING ON ENZYME ACTIVITY
		Using the 't' test for paired samples as the mode of statistical analysis, in all three trials the 'healed' enzyme was found to have a significantly higher level of activity than the untreated control (P( 0.01) and in one trial to differ significantly from the unhealed control (P( 0.01).
		To test the hypothesis that hands-on healing influences the activity of enzymes, which in turn might account for the many reports that healing stimulates the body's own healing processes.
		Prior to mixing, one test tube of enzyme was exposed to a healer's hands, a second to a non-healer's hands while the third remained untreated.
	www.webserve.co.uk /bunnell/enzyme.html

	Elevations in Cathepsin B Protein Content and Enzyme Activity Occur Independently of Glycosylation during Colorectal Tumor Progression -- Iacobuzio-Donahue et al. 272 (46): 29190 -- Journal of Biological Chemistry
		To determine cathepsin B enzyme activity, the cathepsin B-specific substrate, Z-Ala-Arg-Arg-MNA was used.
		enzyme activity to be frequently and significantly elevated in
		B enzyme activity in the normal extraction was 42.40 nmol/mg/min;
	www.jbc.org /cgi/content/full/272/46/29190

	Enzyme Activity
		BarleyMax has a very high level of enzyme activity which make the vitamins and minerals in BarleyMax easily used by the body.
		Enzymes are the life force of raw foods.
		Edward Howell, biochemist and nutrition researcher shows us how important food enzymes from raw foods are in maintaining optimal health and conserving the body's enzyme potential for vital functions.
	www.divinehealth.com /enzyme_activity.htm

	Regulation of the angiotensin-converting enzyme activity by a time-course hypoxia in the carotid body -- Lam et al. 96 (2): 809 -- Journal of Applied Physiology
		Regulation of the angiotensin-converting enzyme activity by a time-course hypoxia in the carotid body -- Lam et al.
		Regulation of the angiotensin-converting enzyme activity by a time-course hypoxia in the carotid body
		II in the carotid body and thus its agonist action at the AT receptor.
	www.jap.org /cgi/content/abstract/96/2/809

	Skeletal Muscle Lipid Content and Oxidative Enzyme Activity in Relation to Muscle Fiber Type in Type 2 Diabetes and Obesity -- He et al. 50 (4): 817 -- Diabetes
		Oxidative enzyme activity was greater in lean subjects than in obese or type 2 diabetic subjects for all three fiber types.
		There was not a significant difference in skeletal muscle glycolytic enzyme activity in lean, obese, or type 2 diabetic subjects within each fiber type.
		in the activities of oxidative enzyme citrate synthase, cytochrome
	diabetes.diabetesjournals.org /cgi/content/full/50/4/817

	Restriction Enzyme Digestion of DNA: Introduction
		This activity is designed to enhance your understanding and retention by illustrating DNA structure, restriction enzyme digestion of DNA, analysis of digested DNA by agarose gel electrophoresis, and the principles involved in constructing a restriction map from primary data.
		Restriction enzymes are enzymes isolated from bacteria that recognize specific sequences in DNA and then cut the DNA to produce fragments, called restriction fragments.
		Restriction enzymes play a very important role in the construction of recombinant DNA molecules, as is done in gene cloning experiments.
	www.phschool.com /science/biology_place/biocoach/red/intro.html

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