Sandbox Reserved 660: Difference between revisions

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ATP+4-coumarate+CoA <--> AMP+ diphosphate+4-coumaroyl-CoA.

Ligase in the enzymology, is is an enzyme that catalyze the joining of two large molecule by forming new chemical bond. In the process of catalysis, there is always hydrolysis of small molecule group accompanying. 4CL ligase, sepcifically, catalyzes the formation of carbon sulfur bond between two reactants.

Ligase in the enzymology, is an enzyme that catalyze the joining of two large molecule by forming new chemical bond. In the process of catalysis, there is always hydrolysis of small molecule group accompanying. 4CL ligase, sepcifically, catalyzes the formation of carbon sulfur bond between two reactants.

4CL is one of the key enzyme regulating the synthesis of monolignols in the lignin pathway. Lignin is an unique and complex phenylpropanoid polymer which plays key role in plant development and response to the environment. Lignin is typically polymerized from 3 phenylpropanoid ~~mononers~~ , p-coumaryl (H), coniferyl (G) and sinapyl (S)[1]. The relative amounts of these 3 monomers found in lignin show plant specificity and 4CL is one of the main enzymes participating the formation these 3 monomers in the regulatory network of the monolignol pathway and has significant effect on the S/G ratio which is substantial to the lignin formation ~~situation~~ in the plant. There is report showing that the 4CL gene knock-down will result in the lignin reduction[2]. In other words, the activity of 4CL determines the overall carbon flow of the phenylpropanoid pathway. For this reason, 4CL has been focused on the genetic engineering regulation about the plants products quality improvement.

4CL is one of the key enzyme regulating the synthesis of monolignols in the lignin pathway. Lignin is an unique and complex phenylpropanoid polymer which plays key role in plant development and response to the environment. Lignin is typically polymerized from 3 phenylpropanoid monomers , p-coumaryl (H), coniferyl (G) and sinapyl (S)[1]. The relative amounts of these 3 monomers found in lignin show plant specificity and 4CL is one of the main enzymes participating the formation these 3 monomers in the regulatory network of the monolignol pathway and has significant effect on the S/G ratio which is substantial to the lignin formation in the plant. There is report showing that the 4CL gene knock-down will result in the lignin reduction[2]. In other words, the activity of 4CL determines the overall carbon flow of the phenylpropanoid pathway. For this reason, 4CL has been focused on the genetic engineering regulation about the plants products quality improvement.

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==Enzymatic Mechanism==

[[Image:Mechanism for zy.png | thumb]]

The enzymaticmechanism begins with the binding of ATP and hydroxycinnamate substrates. The binding results in 4CL1 adopting the catalytic conformation for the adenylate-forming partial reaction, in which the side chain of Lys-523 interacts with and directs the carboxylate group of the bound hydroxycinnamates for the nucleophilic attack of the α-phosphate of ATP, resulting in an AMP-hydroxycinnamate conjugate and a PPi molecule. The release of PPi then propels 4CL1 to the catalytic conformation of the thioester-forming partial reaction. In this conformation, the side chain of His-234 swings aside to allow access of CoA to the AMP-hydroxycinnamate conjugate. The AMP-hydroxycinnamate conjugate and CoA are then catalyzed by side chains of Lys-438 and Gln-443 to form the ﬁnal thioester product. The C-domain rotates again to expose the substrate binding site, and the thioester and AMP are released[3].

==Implication==

Sandbox Reserved 660: Difference between revisions

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@@ Line 11: / Line 11: @@
 ATP+4-coumarate+CoA <--> AMP+ diphosphate+4-coumaroyl-CoA.
-Ligase in the enzymology, is is an enzyme that catalyze the joining of two large molecule by forming new chemical bond. In the process of catalysis, there is always hydrolysis of small molecule group accompanying. 4CL ligase, sepcifically, catalyzes the formation of carbon sulfur bond between two reactants.
+Ligase in the enzymology, is an enzyme that catalyze the joining of two large molecule by forming new chemical bond. In the process of catalysis, there is always hydrolysis of small molecule group accompanying. 4CL ligase, sepcifically, catalyzes the formation of carbon sulfur bond between two reactants.
-CL is one of the key enzyme regulating the synthesis of monolignols in the lignin pathway. Lignin is an unique and complex phenylpropanoid polymer which plays key role in plant development and response to the environment. Lignin is typically polymerized from 3 phenylpropanoid mononers , p-coumaryl  (H),  coniferyl  (G)  and  sinapyl (S)[1]. The relative amounts of these 3 monomers found in lignin show plant specificity and 4CL is one of the main enzymes participating the formation these 3 monomers in the regulatory network of the monolignol pathway and has significant effect on the S/G ratio which is substantial to the lignin formation situation in the plant. There is report showing that the 4CL gene knock-down will result in the lignin reduction[2]. In other words, the activity of 4CL determines the overall carbon flow of the phenylpropanoid pathway. For this reason, 4CL has been focused on the genetic engineering regulation about the plants products quality improvement.
+CL is one of the key enzyme regulating the synthesis of monolignols in the lignin pathway. Lignin is an unique and complex phenylpropanoid polymer which plays key role in plant development and response to the environment. Lignin is typically polymerized from 3 phenylpropanoid monomers , p-coumaryl  (H),  coniferyl  (G)  and  sinapyl (S)[1]. The relative amounts of these 3 monomers found in lignin show plant specificity and 4CL is one of the main enzymes participating the formation these 3 monomers in the regulatory network of the monolignol pathway and has significant effect on the S/G ratio which is substantial to the lignin formation in the plant. There is report showing that the 4CL gene knock-down will result in the lignin reduction[2]. In other words, the activity of 4CL determines the overall carbon flow of the phenylpropanoid pathway. For this reason, 4CL has been focused on the genetic engineering regulation about the plants products quality improvement.
@@ Line 28: / Line 28: @@
 ==Enzymatic Mechanism==
+[[Image:Mechanism for zy.png | thumb]]
 The enzymaticmechanism begins with the binding of ATP and hydroxycinnamate substrates. The binding results in 4CL1 adopting the catalytic conformation for the adenylate-forming partial reaction, in which the side chain of Lys-523 interacts with and directs the carboxylate group of the bound  hydroxycinnamates  for  the  nucleophilic  attack  of  the α-phosphate  of  ATP,  resulting  in  an  AMP-hydroxycinnamate conjugate and a PPi molecule. The release of PPi then propels 4CL1  to  the  catalytic  conformation  of  the  thioester-forming partial reaction.  In this conformation,  the side chain of His-234 swings aside to allow access of CoA to the AMP-hydroxycinnamate conjugate. The AMP-hydroxycinnamate conjugate and CoA are then catalyzed by side chains of Lys-438 and Gln-443 to form the ﬁnal thioester product. The C-domain rotates again to expose the substrate binding site, and the thioester and AMP are released[3].
 ==Implication==