...Enzymes activity plays an important role on living organisms. Its activity can be affected by different factors, including environmental and molecular elements. Enzyme inhibition by some molecules can be competitive or noncompetitive according to the binding mechanism. The aim of this study was to determine the type of inhibition occurred by the phenylthiourea (PTU) on the catechol oxidase enzyme. Different substrate concentrations, 0.5, 1, and 1.5 mL, and presence (1mL) and absent of PTU was analyzed. Products were measured at 380 nm. Results showed product only when PTU was not present, except for in one tube. A PTU noncompetitive inhibition is proposed based on the inability to obtained product even when the substrate concentration is increased....
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... The results of the experiment did not support the created hypothesis that the poisonous enzyme PTU (Phenylthiourea) was a competitive inhibitor. In the experiment to test whether PTU was competitive a catechol oxidase substrate was added to the solution to determine it’s inhibition. As more of the substrate was added, no reaction occurred and the substance remained consistently clear. However, the results indicated that the catechol that was used continued to be inhibited by the PTU. Due to this inhibition, catechol oxidase was present in potatoes and the results suggested opposite from the hypothesis. Enzyme inhibitors are compounds that counteract substrate-enzyme interactions. Two classes of enzyme inhibitors are competitive and noncompetitive. Enzyme inhibitors work as one of the major controls in the biological systems. Competitive inhibitors act in the spot that are meant to be for it’s intended substrate. At any given moment enzymes may bind to its inhibitor, the substrate or neither. They are unable to bind to both at the same time. This inhibition competes with the substrate for binding sites on the enzymes. However, a competitive inhibitor is reversible if the concentration of the substrate is raised to high levels while the inhibitor is constant. Noncompetitive inhibitors do not compete for its position in the active site. It decreases the activity of the enzyme and binds equally even if it’s bound to the substrate or not. This causes the conformations...
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...Catechol oxidase is an interesting compound to work with, because of this chemical fruits and vegetables turn brown when dropped or cut. I will know how catechol oxidase performs under different pH levels using a spectrophotometer to record its absorbance. This will give the information to determine if more or less product is being made. After performing the test and understanding the results I will compare the difference between absorbance, and if any problems occurred during the process. Introduction Have you walked into a grocery store and noticed that some fruits and vegetables have brown spots on them, they no longer look fresh? For example, when you buy bananas and cut them at home and walk away and ten minutes later they have started to turn brown on the edges. The name for that reaction is catechol oxidase, which is made into the pigment called benzoquinone. In this experiment I will investigate catechol oxidase. The enzyme is a catalyst which makes some chemical reactions occur faster than if no enzyme was present. I will test how well catechol oxidase will function under different conditions, what happens in different pH and the absorbance of each. Catechol oxidase needs copper in order to active, during the process of oxidation electrons and hydrogens are eliminated from catechol. Like stated above the compound...
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...Effect of pH on Enzyme Activity and Benzoquinone Absorption Enzymes are partially or wholly proteins which help catalyze enzymatic reactions. As hypothesized, catechol oxidase (enzyme) was not able to function in a very acidic pH (pH 2) or a highly basic pH (pH 11). In both cases the catechol oxidase activity was decreased which resulted in minimum production of benzoquinone (product). Even though the original hypothesis was not completely supported, however, as seen in figure 1, the absorbance for the mixture is at its highest when the reaction occurs in the presence of a pH 8 buffer, which is close to the pH 7 originally hypothesized. The catechol oxidase is affected by the different pH concentration, and its most favorable pH value is pH...
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...In the presence of oxygen, catechol oxidase catalyze the removal of hydrogen electrons from catechol. Catechol is found in certain plants and is converted to benzoquinone, a pigment that is responsible for the browning of the surface (Schultz, 2006). This enzyme functions as a defense mechanism. Catechol oxidase is a naturally occurring antiseptic which protects damaged plants and vegetables against disease. This enzyme can be found in a variety of foods such as apricots, pears, bananas, mushrooms, and lettuce (Hawley, 2007). This experiment will examine for the presence of catechol oxidase in three particular foods: sweet potatoes, apples, and pears. Is catechol oxidase present in sweet potatoes, apples, and pears? This experiment hopes to address the question, is catechol oxidase present in apples, pears, and not sweet potatoes? The alternate hypothesis is catechol oxidase is present in sweet potatoes but not...
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...On my honor, I indicate with my personal signature that the work presented here is my own, and has not been plagiarized from another student or another source, in accordance with the honor code of University of the Pacific. (Please sign by typing your name or pasting an electronic signature if you have one) Signature: Jennae Fenton Date: 10/12/17 Abstract: The enzyme catechol oxidase is a protein that produces benzoquinone when the substrate catechol binds to the enzyme. This is commonly referred to as browning. How quickly produce spoils...
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...effect of temperature, pH, and substrate concentration on Enzyme activity? Purpose: Enzymes are proteins that speed up chemical reactions in cells. They break down molecules called substrates. Each enzymes have only one substrate that breaks down. Enzymes are produced in the cells of the body and affect the rate of almost all the chemical reactions which take place in living organisms. The rate of enzymes activity is influenced by temperature, pH, and substrate concentration. The purpose of this lab was to determine the affects of enzyme activity under specific temperature changes, pH values and substrate concentration. Since heat increases the rate of most chemical reactions, the addition of heat causes faster molecular movement. Most enzymes active in living tissue becomes denatured, their secondary or tertiary protein structure breaks down, at the temperature above 40 degrees C. In the effects of pH, it is expected that the changes in pH would have an effect on the action of enzymes. Lemon juice helps keep the apple from growing, because its full of ascorbic acid (Vitamin C) and it has a low acidic pH level. But extreme high levels of low pH values can result in a complete loss of enzymes activity thus leaving the apple to brown. The effects of substrate concentration, an enzyme substrate complex is formed when a substrate fits into active of an enzyme. The velocity, the rate of speed, at which the enzymes works will increase until it reaches a maximum. If the...
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...Step 1: Gather all the necessary materials. Place the beaker of enzyme (potato juice) in the plastic container, and fill the surrounding area around the beaker in the container with ice. Step 2: Take the Sharpie marker and label each of the 7 test tubes as follows. C1, C2(These will be the control variables) 1,2,3,4,5(these will be the experimental variables). Step3: Once all the test tubes are labeled with the correct number place each one in the test tube rack in in order from C1 to C2 on one side of the rack and test tubes 1 through 5 on the other side of the rack. Step 4: Using the graduated cylinder, measure out 10mL of the water with a pH of 7. Pour the water into one of the test tubes. Repeat this step until all 7 of the test...
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...percentages go up in tubes 2 and 3 but after 10 minutes the measured absorbance starts to decline, signaling the start of mitochondrial production. PTU is definitely limited in its effect of being a non-competitive inhibitor, once it is used up the remaining and unaffected mitochondria will continue cellular respiration. Through these results we can rationalize that if a human were to come in contact with the PTU toxin the effects can be limited to time. Another experiment also tested PTU as an inhibitor to catechol oxidase, a type of enzyme found in fruits. This enzyme is found in several places of a plant cell, one of these places is also in the mitochondria (Shomer, I., 1979). The solution of PTU used was at 0.02 Molarity with 0.02 to 0.12 concentration of catechol oxidase. One of the graphs given help proves our hypothesis, that PTU does indeed halt mitochondrial production. Their graph shows that PTU stunts the browning of a banana, an effect caused by the oxidation of catechol by aerobic respiration...
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...PHYSIOLOGICAL STUDIES OF THE FRUITS OF THE PINEAPPLE [ANANAS COMOSUS (L.) MERR.] WITH SPECIAL REFERENCE TO PHYSIOLOGICAL BREAKDOWN ERSTON V. MILLER Received July 17, 1950 Introduction Physiological breakdown of the fruits of the pineapple [Ananas comosus (L.) Merr.] is characterized by a darkening of the flesh of the fruitlets, beginning near their attachment to the core in a region an inch or two above the base of the fruit. The-disorder progresses upward and outward, subsequently involving all of the fruitlet except the ovary and a layer approximately one quarter inch deep below the skin. Only in advanced stages do the surface of the fruit and the core become involved. Hence in most fruits there may be no external symptoms of the disorder. Severe cases of physiological breakdown are frequently discovered in pineapples that appear normal and attractive from the exterior. The disorder is not a form of over-ripeness as is true of "internal breakdown" of apples. One of the commonest causes of physiological breakdown is exposure of the fruits to relatively low temperatures. The disorder has been observed in Florida in the fruits that were induced to ripen during the winter months by forcing the bloom with acetylene gas during "off season." Physiological breakdown has been reported to occur under similar conditions in Australia (3). Also pineapples harvested during the summer months may develop breakdown during storage or transit if holding temperatures are...
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...the throat become rigid so that causes sufferers have difficulty swallowing. Treatment of Parkinson's disease with medication The main symptoms of Parkinson's can be reduced by consuming drugs, but not everyone fits in with these drugs. It is strongly recommended to follow the advice of your doctor if the following drugs will consume. Levodopa This medication will be absorbed by the cell and converted into dopamine compounds to increase dopamine levels in order to help cope with the disruption to the movement of the body of the sufferer. Monoamine oxidase-b inhibitors (MAO-B) The function of these drugs to inhibit the destructive compound dopamine. This medication can help relieve the symptoms of Parkinson's disease although not as strong as the resulting impact of levodopa. Catechol-O-methyltransferase inhibitor (COMT) This drug is only specific to advanced Parkinson's disease sufferers. Its function is to inhibit an enzyme that destroys of levodopa or...
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... Ahmadu Bello University, Zaria, Nigeria. Department of Pharmaceutical and Medicinal Chemistry, Ahmadu Bello University, Zaria, Nigeria. 3 Department of Biochemistry, Ahmadu Bello University, Zaria, Nigeria. 4 Center for Biotechnology Research and Traininig. Ahmadu Bello University, Zaria, Nigeria. * Corresponding author, E-mail: mojitaibat@yahoo.com; Tel.:+2348035896043 1 ABSTRACT Laccase, a multicopper oxidase that catalyzes the oxidation of various aromatics, particularly phenolic substrates, e.g. hydroquinones guaiacol, 2,6-dimethoxyphenol or phenylene diamine, was purified and partially characterised from culture filtrates of a white rot fungus, Lachnocladium sp. This enzyme was purified by anion exchange and gel filtration chromatography. Laccase activity was determined using ABTS (2, 2’-azinobis-(3-ethylbenzthiazoline)-6-sulphonic acid) substrate. The culture filtrate had maximum laccase activity of 1.62 U/ml after 14 days of incubation. The purified laccase had an optimum temperature of 50 oC and its optimum pH was 6 for ABTS. The activity of this enzyme was enhanced by Fe2+, Cu2+, Zn2+and Ca2+, and was inhibited by EDTA and sodium iodide. Laccase from Lachnocladium sp. had a Km of 0.119 mM and a Vmax of 0.313 U. © 2012 International Formulae Group. All rights reserved. Keywords: Lachnocladium sp., anion exchange chromatography, gel filtration chromatography, ABTS, DMP. INTRODUCTION Laccases (EC 1.10.3.2, p-diphenol: dioxygen oxidoreductase) belong to the...
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...Dopamine agonists, MAO-B inhibitors, Catechol O-methyltransferase (COMT) inhibitors, Anticholinergics and Amantadine. Carbidopa-levodopa or Levodopa is the most effective disease medication. It is a natural chemical that passes into the brain and is transformed into dopamine. Levodopa is protected from transforming premature or outside the brain by the protection of carbidop (Parcopa, Sinemet). This lessens side effects, but a patient could still experience nausea or lightheadedness from Levodopa. As mentioned earlier, as the disease progresses, the benefits of levodopa may become less effective. Dyskinesia which is involuntary movements, can take place when taking a high dose of the drug. Dopamine agonists mimic the effects of dopamine in the brain. They aren't as effective as levodopa in treating your symptoms but they last longer. Dopamine agonists may also be used with levodopa to help with the inconsistent effects of levodopa. Examples of Dopamine agonists are: ropinirole (Requip), pramipexole (Mirapex), rotigotine and Neupro. Apomorphine (Apokyn), is a fast-acting injectable which can be used for quick relief. Side effects of dopamine agonists can be similar to carbidopa-levodopa, but also include sleepiness, compulsive behaviors like hypersexuality, swelling, hallucinations, eating and gambling. MAO-B inhibitors include rasagiline (Azilect) and selegiline (Eldepryl, Zelapar). By inhibiting the brain enzyme monoamine oxidase B (MAO-B), they help prevent the breakdown...
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...2008). Many of the ingredients have been directly associated to antidepressant effects. The supplement works through many mechanisms throughout the brain displayed in Figure 2. The supplement inhibits the uptake of serotonin, dopamine, and norepinephrine from the synaptic cleft of the brain neurons. It also blocks the act of binding GABA through inhibiting neuro-inhibitory and gamma aminobutyric acid receptors; this in turn reduces central nervous system depression. The supplement also works to increase the number of 5-HT2 receptors located in the brain’s prefrontal cortex, which has been proven as a way to treat depression. St. John’s wort inhibits the activity of both monoamine oxidase and catechol-O-methyltransferase enzymes, which are precursors of dopamine. Through inhibiting the precursors the enzymes are blocking the metabolization of dopamine into norepinephrine, which allows for the dopamine to act for longer periods of time in the brain. Although there are an overwhelming amount of mechanisms occurring, St. John’s wort offers only minimal benefits in treating mild to moderate depression (Pharmacology Weekly, 2008). According to Pharmacology Weekly, the minimal benefits occurring could be due to the dosage form or extract of the supplement. St. John’s wort acts similar to a selective serotonin reuptake inhibitor (SSRI), which is a form of commonly prescribed antidepressant. The fact that SSRIs are synthetically made can offer control of the dosage form and extract that...
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...Hydrocarbons Vijay Kothari*, Meera Panchal, Namrata Srivastava Institute of Science, Nirma University *Corresponding author: vijay.kothari@nirmauni.ac.in; vijay23112004@yahoo.co.in Abstract Hydrocarbon contamination in the environment has been a notable problem since years. Particularly the major oil spills in last few decades, and resulting loss to biodiversity has brought public attention to this problem. Bioremediation is a promising approach for recovery of environmental sites contaminated with crude oil and other hydrocarbons. Many microorganisms have been identified to possess hydrocarbon degradation potential. This review covers an overview of common hydrocarbon pollutants, microbes known as hydrocarbon degraders, major pathways and enzymes involved therein, factors affecting hydrocarbon degradation, and various approaches employed to exploit degrading capacity of microbes for remedial purpose. In addition to making use of inherent catabolic ability of degrader populations, metabolic engineering can be of considerable value in dealing with the problem of hydrocarbon contamination. Keywords: Bioremediation, Oxygenase, Biomagnification, Cometabolism, Consortium, Biosurfactant. Introduction Hydrocarbon (HC) group of compounds consist of hydrogen and carbon in their structure. As petrochemical industries are flourishing worldwide, HC contamination has become one of the major environmental problems faced globally. Environment is particularly being contaminated with accidental...
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