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Noncompetitive Inhibitors
#1
Noncompetitive Inhibitors
The other type of inhibition is noncompetitive inhibition. In noncompetitive inhibition, a molecule binds to an enzyme somewhere other than the active site. This changes the enzyme's three-dimensional structure so that its active site can still bind substrate with the usual affinity, but is no longer in the optimal arrangement to stabilize the transition state and catalyze the reaction.
On the macroscopic scale, noncompetitive inhibition lowers the Vmax. Thus, the enzyme simply cannot catalyze the reaction with the same efficiency as the uninhibited enzyme. Note that noncompetitive inhibition cannot be overcome by raising the substrate concentration like competitive inhibition can.
Select either uninhibited or inhibited from the boxes below. Then click in the image area to see the course of an uninhibited or a noncompetitively inhibited enzymatic reaction.
For example, the amino acid alanine noncompetitively inhibits the enzyme pyruvate kinase. Alanine is one product of a series of enzyme-catalyzed reactions, the first step of which is catalyzed by pyruvate kinase.

Why does it make sense for the product of an enzymatic chain of reactions to inhibit one of the enzymes earlier in the chain? Type your answer in the space provided, then click on the Check button.
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Some inhibitors have the effects of both competitive and noncompetitive inhibition, i.e., they affect both the enzyme's affinity for substrate and the maximal rate of catalysis. Such inhibitors are called mixed inhibitors
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#2
It means a molecule binds to an enzyme somewhere other than the active site.This means the 3-D structure of the enzymes get changed.
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#3
(09-15-2012, 03:43 PM)davidflora Wrote: It means a molecule binds to an enzyme somewhere other than the active site.This means the 3-D structure of the enzymes get changed.

Living organism are able to control thier metabolism by various means at molecular levels. Living organism has a self regulating system within their body. Enzymes are the main proteins in many biochemical pathways with helps in completing the specific biochemical reaction. They are biological catalyst. Some unique mechanism of our body helps in regulating enzymes functions. Enzymes are the three dimensional proteins which work on lock and key methods having active site as reaction site with specific substrate.
All enzymes are protein but all proteins are not enzymes. Many enzymes get inhibited either for some time or even permanently. Enzymes inhibition mechanism is divided into two types Competitive inhibition- in this inhibitor competes with the substance at active site of enzyme, Noncompetitive inhibition-inhibitor attach to the different site of enzyme rather than active site, Uncompetitive inhibitions-is a result of combination of enzyme plus substance plus inhibitor, Allosteric inhibition-act on allosteric site rather than active site and hamper the active site and substance combination, Partial inhibition-inhibits the enzyme active site partially, Tight-Binding inhibition-uses all ways to bind the enzyme and inhibits the enzyme action, and Time dependent inhibition- shows binding slowly and reduce the enzyme turnover rate.
All types of enzyme inhibition are now studied in every detail and are therefore being used in treatment of many diseases. Today many enzymes inhibitors are used in treating deadly diseases like cancers, in which betaine-homocysteine-S-methyltransferase (BHMT) is used which converts homocysteine to methionine as cancer cell needs high methionine concentrations, if methionines production reduces will affect the cancer cells development and thus act as treatment during cancer development.
One such another example is Angiotensin II helps in treatment of disease of circulatory system. Angiotensin II formed from Angiotensin I by the angiotensin converting enzyme (ACE). This inhibitors help in treating blood pressure and many kidney diseases. Nonsteroidal anti-inflammatory drugs (NSAIDs) are pain killers and are the nothing but the Cyclooxygenase -2 inhibitors (COX-2) which hinbitis the prostaglandins biochemical pathway and relive the pain.
This is just the beginning of use of enzyme inhibitor in various treatments. With new developments & research in this field, this concept will soon help us to treat the serious diseases very effectively!

(10-14-2012, 08:53 PM)ExpertScie Wrote:
(09-15-2012, 03:43 PM)davidflora Wrote: It means a molecule binds to an enzyme somewhere other than the active site.This means the 3-D structure of the enzymes get changed.

Living organism are able to control thier metabolism by various means at molecular levels. Living organism has a self regulating system within their body. Enzymes are the main proteins in many biochemical pathways with helps in completing the specific biochemical reaction. They are biological catalyst. Some unique mechanism of our body helps in regulating enzymes functions. Enzymes are the three dimensional proteins which work on lock and key methods having active site as reaction site with specific substrate.
All enzymes are protein but all proteins are not enzymes. Many enzymes get inhibited either for some time or even permanently. Enzymes inhibition mechanism is divided into two types Competitive inhibition- in this inhibitor competes with the substance at active site of enzyme, Noncompetitive inhibition-inhibitor attach to the different site of enzyme rather than active site, Uncompetitive inhibitions-is a result of combination of enzyme plus substance plus inhibitor, Allosteric inhibition-act on allosteric site rather than active site and hamper the active site and substance combination, Partial inhibition-inhibits the enzyme active site partially, Tight-Binding inhibition-uses all ways to bind the enzyme and inhibits the enzyme action, and Time dependent inhibition- shows binding slowly and reduce the enzyme turnover rate.
All types of enzyme inhibition are now studied in every detail and are therefore being used in treatment of many diseases. Today many enzymes inhibitors are used in treating deadly diseases like cancers, in which betaine-homocysteine-S-methyltransferase (BHMT) is used which converts homocysteine to methionine as cancer cell needs high methionine concentrations, if methionines production reduces will affect the cancer cells development and thus act as treatment during cancer development.
One such another example is Angiotensin II helps in treatment of disease of circulatory system. Angiotensin II formed from Angiotensin I by the angiotensin converting enzyme (ACE). This inhibitors help in treating blood pressure and many kidney diseases. Nonsteroidal anti-inflammatory drugs (NSAIDs) are pain killers and are the nothing but the Cyclooxygenase -2 inhibitors (COX-2) which hinbitis the prostaglandins biochemical pathway and relive the pain.
This is just the beginning of use of enzyme inhibitor in various treatments. With new developments & research in this field, this concept will soon help us to treat the serious diseases very effectively!

Dear All Friends,
Can anyone explain this ?
"All enzymes are protein but all proteins are not enzyme" Recently, there is a surprise result in this field... meanwhile any explanation ?
-Regards
Expertscie.
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