McClintic sandbox 1 - Revision history

J.D. McClintic: /* Kinetics */

J.D. McClintic — Fri, 22 Apr 2011 19:21:45 GMT

Kinetics

←Older revision		Revision as of 19:21, 22 April 2011
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	==Kinetics==		==Kinetics==
-	It has been shown in ''E. coli'' that Succinyl Coa sythetase does not have a steady state kinetic pattern. What has been seen is a kinetic pattern that is consistent when the sequential addition of all substrates is done, to form a quaternary structure before releasing any products. This would then give evidence of a limitation on the initial rate kinetics. This is because the order of substrate attachment and product release is limited.<ref> Frank J. Moffet and W. A. Bridger. The Kinetics of Succinyl Coenzyme A Synthetase from Escherichia coli : A REACTION WITH A COVALENT ENZYME-SUBSTRATE INTERMEDIATE NOT EXHIBITING "PING-PONG" KINETICS J. Biol. Chem. 1970 245: 2758-2762.[http://www.jbc.org/content/245/10/2758.short]</ref>	+	It has been shown in ''E. coli'' that Succinyl Coa sythetase does not have a steady state kinetic pattern. What has been seen is a kinetic pattern that is consistent when the sequential addition of all substrates is done, to form a quaternary structure before releasing any products. This would then give evidence of a limitation on the initial rate kinetics. This is because the order of substrate attachment and product release is limited.<ref> Frank J. Moffet and W. A. Bridger. The Kinetics of Succinyl Coenzyme A Synthetase from Escherichia coli : A REACTION WITH A COVALENT ENZYME-SUBSTRATE INTERMEDIATE NOT EXHIBITING "PING-PONG" KINETICS J. Biol. Chem. 1970 245: 2758-2762.[http://www.jbc.org/content/245/10/2758.short]</ref> And as seen previously the reaction is dependent on the presence of either GDP and GTP or ATP and ADP and the amount of concentrations that they are present at.

	==Regulation==		==Regulation==

J.D. McClintic: /* Kinetics */

J.D. McClintic — Fri, 22 Apr 2011 19:19:39 GMT

Kinetics

←Older revision		Revision as of 19:19, 22 April 2011
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	==Kinetics==		==Kinetics==
-	~~As stated earlier,~~ the ~~presence~~ of ~~GTP~~, ~~GDP, ATP, and ADP can be either activating or inhibiting depending~~ on the ~~stage of catalysis it interacts with~~ the ~~enzyme~~.	+	It has been shown in ''E. coli'' that Succinyl Coa sythetase does not have a steady state kinetic pattern. What has been seen is a kinetic pattern that is consistent when the sequential addition of all substrates is done, to form a quaternary structure before releasing any products. This would then give evidence of a limitation on the initial rate kinetics. This is because the order of substrate attachment and product release is limited.<ref> Frank J. Moffet and W. A. Bridger. The Kinetics of Succinyl Coenzyme A Synthetase from Escherichia coli : A REACTION WITH A COVALENT ENZYME-SUBSTRATE INTERMEDIATE NOT EXHIBITING "PING-PONG" KINETICS J. Biol. Chem. 1970 245: 2758-2762.[http://www.jbc.org/content/245/10/2758.short]</ref>

	==Regulation==		==Regulation==

J.D. McClintic: /* Regulation */

J.D. McClintic — Fri, 22 Apr 2011 18:55:46 GMT

Regulation

←Older revision		Revision as of 18:55, 22 April 2011
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	==Regulation==		==Regulation==
-	Succinyl-CoA synthetase is not a major regulator in the Krebs cycle, making it dependent on the steps prior. However, there has been evidence that a high-affinity GDP-binding site does allosterically regulate the activity of the enzyme. It has also been seen that the binding of GDP to these allosteric sites actually leads to an increase in the rate of phosphorylation of Succinyl-Coa synthetase. This could be due to the fact that GDP is probably altering the affinity of the enzyme for GTP.<ref>~~PMCID~~: ~~1134635~~</ref>	+	Succinyl-CoA synthetase is not a major regulator in the Krebs cycle, making it dependent on the steps prior. However, there has been evidence that a high-affinity GDP-binding site does allosterically regulate the activity of the enzyme. It has also been seen that the binding of GDP to these allosteric sites actually leads to an increase in the rate of phosphorylation of Succinyl-Coa synthetase. This could be due to the fact that GDP is probably altering the affinity of the enzyme for GTP.<ref>Um, H.-D., and C. Klein. 1993. Evidence for allosteric regulation of succinyl-CoA synthetase. Biochem. J. 295:821–826.[http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1134635/]</ref>

	==Additional Resources==		==Additional Resources==

J.D. McClintic: /* Regulation */

J.D. McClintic — Fri, 22 Apr 2011 18:48:57 GMT

Regulation

←Older revision		Revision as of 18:48, 22 April 2011
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	==Regulation==		==Regulation==
-	Succinyl-CoA synthetase is not a major regulator in the Krebs cycle, making it dependent on the steps prior. However, there has been evidence that a high-affinity GDP-binding site does allosterically regulate the activity of the enzyme. It has also been seen that the binding of GDP to these allosteric sites actually leads to an increase in the rate of phosphorylation of Succinyl-Coa synthetase. This could be due to the fact that GDP is probably altering the affinity of the enzyme for GTP.<ref>~~PMID~~: 1134635</ref>	+	Succinyl-CoA synthetase is not a major regulator in the Krebs cycle, making it dependent on the steps prior. However, there has been evidence that a high-affinity GDP-binding site does allosterically regulate the activity of the enzyme. It has also been seen that the binding of GDP to these allosteric sites actually leads to an increase in the rate of phosphorylation of Succinyl-Coa synthetase. This could be due to the fact that GDP is probably altering the affinity of the enzyme for GTP.<ref>PMCID: 1134635</ref>

	==Additional Resources==		==Additional Resources==

J.D. McClintic: /* Regulation */

J.D. McClintic — Fri, 22 Apr 2011 18:47:38 GMT

Regulation

←Older revision		Revision as of 18:47, 22 April 2011
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	==Regulation==		==Regulation==
-	Succinyl-CoA synthetase is not a major regulator in the Krebs cycle, making it dependent on the steps prior. However, there has been evidence that a high-affinity GDP-binding site does allosterically regulate the activity of the enzyme. It has also been seen that the binding of GDP to these allosteric sites actually leads to an increase in the rate of phosphorylation of Succinyl-Coa synthetase. This could be due to the fact that GDP is probably altering the affinity of the enzyme for GTP.~~[http~~:/~~/www.ncbi.nlm.nih.gov/pmc/articles/PMC1134635/pdf/biochemj00100-0198.pdf]~~	+	Succinyl-CoA synthetase is not a major regulator in the Krebs cycle, making it dependent on the steps prior. However, there has been evidence that a high-affinity GDP-binding site does allosterically regulate the activity of the enzyme. It has also been seen that the binding of GDP to these allosteric sites actually leads to an increase in the rate of phosphorylation of Succinyl-Coa synthetase. This could be due to the fact that GDP is probably altering the affinity of the enzyme for GTP.<ref>PMID: 1134635</ref>

	==Additional Resources==		==Additional Resources==

J.D. McClintic at 18:38, 22 April 2011

J.D. McClintic — Fri, 22 Apr 2011 18:38:43 GMT

←Older revision		Revision as of 18:38, 22 April 2011
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	==Regulation==		==Regulation==
-	Succinyl-CoA synthetase is not a major regulator in the Krebs cycle, making it dependent on the steps prior. However, there has been evidence that a high-affinity GDP-binding site does allosterically regulate the activity of the enzyme. It has also been seen that the binding of GDP to these allosteric sites actually leads to an increase in the rate of phosphorylation of Succinyl-Coa synthetase. This could be due to the fact that GDP is probably altering the affinity of the enzyme for GTP.	+	Succinyl-CoA synthetase is not a major regulator in the Krebs cycle, making it dependent on the steps prior. However, there has been evidence that a high-affinity GDP-binding site does allosterically regulate the activity of the enzyme. It has also been seen that the binding of GDP to these allosteric sites actually leads to an increase in the rate of phosphorylation of Succinyl-Coa synthetase. This could be due to the fact that GDP is probably altering the affinity of the enzyme for GTP.[http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1134635/pdf/biochemj00100-0198.pdf]

	==Additional Resources==		==Additional Resources==

J.D. McClintic: /* Regulation */

J.D. McClintic — Fri, 22 Apr 2011 18:26:56 GMT

Regulation

←Older revision		Revision as of 18:26, 22 April 2011
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	==Regulation==		==Regulation==
-	Succinyl-CoA synthetase is not a major regulator in the Krebs cycle, making it dependent on the steps prior.	+	Succinyl-CoA synthetase is not a major regulator in the Krebs cycle, making it dependent on the steps prior. However, there has been evidence that a high-affinity GDP-binding site does allosterically regulate the activity of the enzyme. It has also been seen that the binding of GDP to these allosteric sites actually leads to an increase in the rate of phosphorylation of Succinyl-Coa synthetase. This could be due to the fact that GDP is probably altering the affinity of the enzyme for GTP.

	==Additional Resources==		==Additional Resources==

J.D. McClintic at 18:14, 22 April 2011

J.D. McClintic — Fri, 22 Apr 2011 18:14:38 GMT

←Older revision		Revision as of 18:14, 22 April 2011
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	<applet load='1cqj' size='300' frame='true' align='right' caption='Structure of succinyl-CoA synthetase' />		<applet load='1cqj' size='300' frame='true' align='right' caption='Structure of succinyl-CoA synthetase' />

-	'''Succinyl-Coa synthetase''' catalyzes the reversible reaction of succinyl-CoA + NDP + Pi <-> succinate + CoA + NTP (where N is either adenosine or guanosine. It can be found in Escherichia coli~~. It~~ is the fifth step in the citric acid cycle.	+	'''Succinyl-Coa synthetase''' catalyzes the reversible reaction of succinyl-CoA + NDP + Pi <-> succinate + CoA + NTP (where N is either adenosine or guanosine. It can be found in Escherichia coli and is the fifth step in the citric acid cycle. Due to its involvement in the citric acid cycle it is very important in all living cells that use oxygen as a part of cellular respiration. This entire process (Citric acid cycle) is necessary in producing one GTP or ATP, three NADHs, and two carbon dioxides.

	==Structure==		==Structure==

J.D. McClintic at 14:57, 22 April 2011

J.D. McClintic — Fri, 22 Apr 2011 14:57:35 GMT

←Older revision		Revision as of 14:57, 22 April 2011
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	==Mechanism==		==Mechanism==
	The histidine residue involved in the (de)phosphorylation of (ATP)ADP acts through the following mechanism.		The histidine residue involved in the (de)phosphorylation of (ATP)ADP acts through the following mechanism.
-	[[Image:Synthetase_mechanism.jpg]]

	A cooperative binding catalysis mechanism has been proposed and it has been shown that binding of ATP at one catalytic site promotes catalytic activity at another catalysis site.<ref>PMID:6997289</ref> It has been shown that the enzyme will bind with ATP in the presence of Mg+2 to form a complex containing 2 ATP residues as well as 2 phosphoric acid residues, after incubation this the complex converts to another one containing 4 phosphoric residues per protein. Only the second complex reacts with succinate and CoA to form the succinyl-CoA complex which then releases as many phosphoric residues as bound succinate.<ref>PMID:570066</ref> A transfer of the phosphoric residue from the first active site is seen to be coordinate with a transfer of a phosphoric residue to the second active site suggesting again a cooperative binding catalysis. This cooperative catalysis means that the presence of ATP or ADP can be both activating and inhibiting depending on the stage of catalysis they interact with the enzyme.		A cooperative binding catalysis mechanism has been proposed and it has been shown that binding of ATP at one catalytic site promotes catalytic activity at another catalysis site.<ref>PMID:6997289</ref> It has been shown that the enzyme will bind with ATP in the presence of Mg+2 to form a complex containing 2 ATP residues as well as 2 phosphoric acid residues, after incubation this the complex converts to another one containing 4 phosphoric residues per protein. Only the second complex reacts with succinate and CoA to form the succinyl-CoA complex which then releases as many phosphoric residues as bound succinate.<ref>PMID:570066</ref> A transfer of the phosphoric residue from the first active site is seen to be coordinate with a transfer of a phosphoric residue to the second active site suggesting again a cooperative binding catalysis. This cooperative catalysis means that the presence of ATP or ADP can be both activating and inhibiting depending on the stage of catalysis they interact with the enzyme.

J.D. McClintic: /* '''Content Donators''' */

J.D. McClintic — Fri, 22 Apr 2011 14:51:18 GMT

'''Content Donators'''

←Older revision		Revision as of 14:51, 22 April 2011
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	{{Clear}}		{{Clear}}
	== '''Content Donators''' ==		== '''Content Donators''' ==
-	Lucas Hamlow	+	Lucas Hamlow,
	David Canner		David Canner