pH and enzymatic reactions,
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Blood Worms?
Hulda Clark Cleanses
The Easier Way to Juice Fast
Reduces cleansing reactions and hunger.
Blood Worms?
Hulda Clark Cleanses
pH and enzymatic reactions,
Hi
The articles below show the importance of pH for the proper enzymatic reactions.
Good Reading
WIEL
--Specificity of enzymatic reactions-- and --electrostatic effects--
From http://en.wikipedia.org/wiki/Enzymes
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Specificity
Enzymes are usually very specific as to which reactions they catalyze and the substrates that are involved in these reactions. Complementary shape, charge and hydrophilic/hydrophobic characteristics of enzymes and substrates are responsible for this specificity. Enzymes can also show impressive levels of stereospecificity, regioselectivity and chemoselectivity.[19]
From http://en.wikipedia.org/wiki/Enzymes
--Beginning of quote--
Specificity
Enzymes are usually very specific as to which reactions they catalyze and the substrates that are involved in these reactions. Complementary shape, charge and hydrophilic/hydrophobic characteristics of enzymes and substrates are responsible for this specificity. Enzymes can also show impressive levels of stereospecificity, regioselectivity and chemoselectivity.[19]
...
"Lock and key" model
Enzymes are very specific, and it was suggested by Emil Fischer in 1894 that this was because both the enzyme and the substrate possess specific complementary geometric shapes that fit exactly into one another.[26] This is often referred to as "the lock and key" model. However, while this model explains enzyme specificity, it fails to explain the stabilization of the transition state that enzymes achieve. The "lock and key" model has proven inaccurate, and the induced fit model is the most currently accepted enzyme-substrate-coenzyme figure.
Enzymes are very specific, and it was suggested by Emil Fischer in 1894 that this was because both the enzyme and the substrate possess specific complementary geometric shapes that fit exactly into one another.[26] This is often referred to as "the lock and key" model. However, while this model explains enzyme specificity, it fails to explain the stabilization of the transition state that enzymes achieve. The "lock and key" model has proven inaccurate, and the induced fit model is the most currently accepted enzyme-substrate-coenzyme figure.
...
Induced fit model
Diagrams to show the induced fit hypothesis of enzyme action.In 1958, Daniel Koshland suggested a modification to the lock and key model: since enzymes are rather flexible structures, the active site is continually reshaped by interactions with the substrate as the substrate interacts with the enzyme.[27] As a result, the substrate does not simply bind to a rigid active site; the amino acid side chains which make up the active site are molded into the precise positions that enable the enzyme to perform its catalytic function. In some cases, such as glycosidases, the substrate molecule also changes shape slightly as it enters the active site.[28] The active site continues to change until the substrate is completely bound, at which point the final shape and charge is determined.[29]
Diagrams to show the induced fit hypothesis of enzyme action.In 1958, Daniel Koshland suggested a modification to the lock and key model: since enzymes are rather flexible structures, the active site is continually reshaped by interactions with the substrate as the substrate interacts with the enzyme.[27] As a result, the substrate does not simply bind to a rigid active site; the amino acid side chains which make up the active site are molded into the precise positions that enable the enzyme to perform its catalytic function. In some cases, such as glycosidases, the substrate molecule also changes shape slightly as it enters the active site.[28] The active site continues to change until the substrate is completely bound, at which point the final shape and charge is determined.[29]
...
Transition State Stabilization
The understanding of the origin of the reduction of ΔG‡ requires one to find out how the enzymes can stabilize its transition state more than the transition state of the uncatalyzed reaction. Apparently, the most effective way for reaching large stabilization is the use of electrostatic effects, in particular, by having a relatively fixed polar environment that is oriented toward the charge distribution of the transition state.[33] Such an environment does not exist in the uncatalyzed reaction in water.
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The understanding of the origin of the reduction of ΔG‡ requires one to find out how the enzymes can stabilize its transition state more than the transition state of the uncatalyzed reaction. Apparently, the most effective way for reaching large stabilization is the use of electrostatic effects, in particular, by having a relatively fixed polar environment that is oriented toward the charge distribution of the transition state.[33] Such an environment does not exist in the uncatalyzed reaction in water.
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--pH influences enzyme activity-- … who could have thought of that
From http://en.wikipedia.org/wiki/Enzyme_kinetics
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Mechanisms of catalysis
The favoured model for the enzyme–substrate interaction is the induced fit model.[40] This model proposes that the initial interaction between enzyme and substrate is relatively weak, but that these weak interactions rapidly induce conformational changes in the enzyme that strengthen binding. These conformational changes also bring catalytic residues in the active site close to the chemical bonds in the substrate that will be altered in the reaction.[41] Conformational changes can be measured using circular dichroism or dual polarisation interferometry. After binding takes place, one or more mechanisms of catalysis lower the energy of the reaction's transition state by providing an alternative chemical pathway for the reaction. Mechanisms of catalysis include catalysis by bond strain; by proximity and orientation; by active-site proton donors or acceptors; covalent catalysis and quantum tunnelling.[30][42]
From http://en.wikipedia.org/wiki/Enzyme_kinetics
--Beginning of quote--
Mechanisms of catalysis
The favoured model for the enzyme–substrate interaction is the induced fit model.[40] This model proposes that the initial interaction between enzyme and substrate is relatively weak, but that these weak interactions rapidly induce conformational changes in the enzyme that strengthen binding. These conformational changes also bring catalytic residues in the active site close to the chemical bonds in the substrate that will be altered in the reaction.[41] Conformational changes can be measured using circular dichroism or dual polarisation interferometry. After binding takes place, one or more mechanisms of catalysis lower the energy of the reaction's transition state by providing an alternative chemical pathway for the reaction. Mechanisms of catalysis include catalysis by bond strain; by proximity and orientation; by active-site proton donors or acceptors; covalent catalysis and quantum tunnelling.[30][42]
...
Enzyme kinetics cannot prove which modes of catalysis are used by an enzyme. However, some kinetic data can suggest possibilities to be examined by other techniques. For example, a ping–pong mechanism with burst-phase pre-steady-state kinetics would suggest covalent catalysis might be important in this enzyme's mechanism. Alternatively, the observation of a strong pH effect on Vmax but not Km might indicate that a residue in the active site needs to be in a particular ionisation state for catalysis to occur.
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There are two ways to increase the rate of a chemical reaction. The first is to raise the temperature, but this method can obviously not be used in a biological system. The second way is to use a catalyst. As shown below, enzymes act as biological catalysts by lowering the activation energy. Thus, more molecules can reach the transition state, and thus more product is formed. Enzymes reduce the activation energy by stabilizing the transition state. This occurs because the shape of the enzyme catalytic site is designed to bind to and stabilize the transition state. Thus, the transition state, a fleeting intermediate, binds to the enzyme more easily than substrate or product. Like all catalysts, enzymes are not consumed in the reaction, but are regenerated following each reaction cycle.
...
Enzyme activity is strongly affected by two additional factors, temperature and pH. Enzymes operate at an optimal temperature, and deviation from this temperature produces a reduction in activity. Most metabolic enzymes function with an optimal temperature near body temperature, but this is not always the case. For example, thermophilic bacteria have metabolic enzymes with optimal temperatures of 85-95 degrees centigrade. Enzymes also operate at a pH optimum, and deviation from this pH produces a reduction in activity. The pH optimum can vary from tissue to tissue (for example, the human enzymes trypsin, pepsin and alkaline phosphatase have pH optima of 8, 1.5-2.5 and 9.5, respectively.
--end of quote--
...
Enzyme activity is strongly affected by two additional factors, temperature and pH. Enzymes operate at an optimal temperature, and deviation from this temperature produces a reduction in activity. Most metabolic enzymes function with an optimal temperature near body temperature, but this is not always the case. For example, thermophilic bacteria have metabolic enzymes with optimal temperatures of 85-95 degrees centigrade. Enzymes also operate at a pH optimum, and deviation from this pH produces a reduction in activity. The pH optimum can vary from tissue to tissue (for example, the human enzymes trypsin, pepsin and alkaline phosphatase have pH optima of 8, 1.5-2.5 and 9.5, respectively.
--end of quote--
EFFECT OF pH UPON THE REACTION KINETICS OF THE ENZYME-SUBSTRATE
http://www.jbc.org/content/194/2/471.full.pdf
http://www.jbc.org/content/194/2/471.full.pdf
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pH and enzymatic reactions,
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