Catalysts and Catalysis

Cellular catalysts are enzymes that increase the rate of chemical reactions within cells by lowering the activation energy required for the reaction to occur. These catalysts speed up biological processes without being consumed in the reaction. They play a critical role in maintaining cellular functions and metabolism.

MnO2 is Manganese (IV) Oxide.

It is also known as manganese dioxide, manganese oxide or as the naturally occurring mineral pyrolusite.

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No, not all catalysts are enzymes. Enzymes are biological catalysts that facilitate chemical reactions in living organisms. Catalysts can be either biological (like enzymes) or synthetic (like transition metals or acid-base catalysts) and they work by lowering the activation energy of a reaction to speed it up.

Protein

Catalyst reformers come in three flavours: non-regenerative, semi-regenerative (SRR) and continuous catalyst regeneration (CCR). The earliest were non-regenerative, most of these are no longer in service. Today most catalytic reformers are SSR and the latset technology (around since 1971 UOP) are CRR.

Catalytic reformers use a solid catalyst (usually chlorinated Pt/alumina or Pt-Re/alumina) under high partial pressures of hydrogen at around 500degC to convert low octane straight run naphtha (usually heavy naphtha: C6-C11, b.p. 140-200degC) into high octane "reformate".

However, the catalyst deactivates over time due to coke build-up and loss of chlorine. A regeneration is required to restore catalyst activity and metals dispersion.

In the semi-regenerative (SRR) version, the reactors have to be taken off-line for regeneration every 6-24 months depending on rate of loss of activity.

In continuous catalyst regeneration (CRR) version a portion of the catalyst is contiuously transferred from the reactor system to a regenerator where it undergoes controlled coke combustion and oxychlorination to restore activity and metals dispersion - without the need to take the unit off-line.

CRR process units can be licenced from UOP or Axens.

Paul Diddams, Intercat

Well, you don't need enzymes (biological catalysts) if you're willing to wait a century or two to digest a burger. Without catalysts, complex reactions like digestion would take too long and the organism could not extract energy from the nutrients it eats in a practical time frame. In addition, speed is everything in the biological world. Some reactions and their speed relative to other organisms reactions determines who survives and who doesn't, among other aspects of life. If a plant is slow to photosynthesize and grow in a habitat high in competition for sunlight real estate, other autotrophs will surely take over.

As with all catalysts, enzymes are not consumed by the reactions they catalyze. What they do is influence the properties of other molecules, sometimes by modifying their orientation, sometimes by pulling or pushing the electron clouds of other molecules, sometimes by forming temporary bonds that change the chemical character of a molecule, sometimes by helping another molecule stretch out or scrunch up to present the reactive sites to other molecules (these are very broad non-scientific descriptions of the actions of enzymes, but hopefully they at least convey the feeling of what is going on). Since enzymes do not actually become part of the products of the reactions they catalyze, they remain available to continue to promote (or in some cases inhibit) reactions until they are destroyed or modified by something outside the reactions they are effecting (like denaturing by heating for example).

The enzyme inhibition constant, also known as the inhibition constant (Ki), is typically determined experimentally by measuring the rate of enzyme activity in the presence of various inhibitor concentrations. By plotting the data and fitting it to an appropriate equation (e.g., Michaelis-Menten or Lineweaver-Burk plot), the Ki value can be calculated. The Ki value represents the concentration of inhibitor required to reduce the enzyme activity by half.

Enzyme

Chlorophyll is NOT really a catalyst. The presence of chlorophyll in the absence of light does not catalyze photosynthesis.

Chlorophyll plays a part in photosynthesis, it captures light energy.

Some enzyme-catalyzed reactions do not involve changes in substrates, products, or cofactors that have easily observable properties (e.g. changes in light absorbance, etc) for the measure of reaction kinetics. In such cases, additional enzymes may be included in the reaction mixture that catalyze a reaction using the product of the first enzymatic reaction as a substrate, metabolizing it to a compound that has more easily measurable properties. If this second reaction is much faster than the first, the kinetics of the overall path approximate the kinetics of the slower reaction alone. This technique can also be used to move spectral peaks of a substrate farther away from those of interfering species, such as peaks normally observed around 280 nm for proteins (due mostly to absorbances oftryptophan, tyrosine and cysteine residues)

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The catalyst for photosynthesis is sunlight. Sunlight provides the energy needed to drive the chemical reactions that convert carbon dioxide and water into glucose and oxygen in the presence of chlorophyll.

In chemistry, they can work by adsorption (although there are other methods). This is when the catalyst attaches itself to the reactant particles and then weakens the bond between them, making it easier to react, thus 'lowering the activation energy' (the energy required for a reaction to start).

so the similarity is that they both speed up the reaction and both have special temperatures they best work at

the only difference between them is that enzymes are found in humans and are not made by humans on particular purpose,whereas chemical catalysts are made by people and are not naturaly developed

Sugar usually would take too long to react to the heat and melt if it wasn't because of the ash. You see, ash is pure carbon, and as such, it catches on fire quite easily. That gives time to sugar to react to the heat f the flame and get on fire too.

Betahistine dihydrochloride and betahistine mesylate are both forms of betahistine, a medication used to treat vertigo and Meniere's disease. The main difference between them is the salt form in which the betahistine is administered - dihydrochloride or mesylate. Both forms are effective in treating vestibular disorders, but some patients may respond better to one form over the other due to individual differences in drug metabolism.

Enymes can change shape when it denatures. An enzyme can denature if it's not at the pH or temperature that it's used to. A denatured enzyme can no longer function (an enzyme's funcion: to speed up/cause chemical reactions fast enough for a living thing to survive).

Enzymes are named by the reaction it catalyzes.

Enzymes are catalysts because they lower the activation energy required for a chemical reaction to occur, thereby speeding up the reaction. They do this by facilitating the formation of the transition state, where the reaction is most likely to occur, and stabilizing it to promote the reaction.

Yes. Apples do indeed have electrons--and they also have protons and neutrons, since they consist of matter, which contains atoms--which, in turn, contain electrons, as well as protons and neutrons.

Stomach enzymes are specialized to function in the acidic environment of the stomach, whereas other enzymes may function in a neutral or alkaline environment. Stomach enzymes such as pepsin are mainly involved in digesting proteins, while other enzymes may have diverse roles in metabolism, signaling, or other biochemical processes. Stomach enzymes are secreted by the stomach lining in response to food intake, while other enzymes may be produced in various organs or tissues throughout the body.

Enzymes are biological catalysts that alter the rate of reactions occurring in the cells. Enzymes are protein in nature. This means that high temperature or extreme pH can denature an enzyme and the damage is irreversible.

Enzymes lower the activation energy of a reaction by providing an alternate path way that has lower activation energy.

Catalysts are used to speed up chemical reactions by lowering the activation energy needed for the reaction to occur. They remain unchanged at the end of the reaction and can be reused multiple times. Catalysts are widely used in industries such as pharmaceuticals, petrochemicals, and environmental applications.

Enzymes are metabolism controlling agent. Enzymes act as a catalyst to increase the efficiency of chemical reactions without being use up of themselves.Enzymes are made up of Proteins.Without participation of enzymes reaction will proceed slowly and making life impossible.

An enzyme that is denatured is one that no longer functions correctly or one that has ceased to function entirely.

An enzyme can become denatured if factors such as pH and temperature are not closely monitored.