Sandbox Wabash 05 Fumarase
From Proteopedia
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==The Active Sites of Fumarase== | ==The Active Sites of Fumarase== | ||
<Structure load='1stp' size='350' frame='true' align='right' caption='Insert caption here' scene='Insert optional scene name here' /> | <Structure load='1stp' size='350' frame='true' align='right' caption='Insert caption here' scene='Insert optional scene name here' /> | ||
| - | <scene name='72/725900/Fumarase/1'>Fumarase</scene> is an enzyme that catalyzes the hydration/dehydration reaction that converts fumarate into malate and vice versa. After extensive experimental studies on this particular enzyme, researchers discovered fumarase has two sites that are involved in carboxylic acid binding. These sites are known as the A-site and the B-site. These two sites are both composed of hisitdine residues that act as the basic group to interact with carboxylic acids and water in their respective binding sites. However, during initial discovery of the two sites, a question arose about which site acted as the active site for the enzyme and catalyzed the fumarate to malate reaction. Weaver, Lees, and Banaszak were able to determine that the A-site is the true active site of fumarase by implementing mutations on each of the sites by using E.Coli and performing PCR using recombinant DNA. The A-site histidine, which is involved in binding, is <scene name='72/725900/His_188/3'>HIS-188</scene> and the B-site histidine is <scene name='72/725900/His_129/2'> | + | <scene name='72/725900/Fumarase/1'>Fumarase</scene> is an enzyme that catalyzes the hydration/dehydration reaction that converts fumarate into malate and vice versa. After extensive experimental studies on this particular enzyme, researchers discovered fumarase has two sites that are involved in carboxylic acid binding. These sites are known as the A-site and the B-site. These two sites are both composed of hisitdine residues that act as the basic group to interact with carboxylic acids and water in their respective binding sites. However, during initial discovery of the two sites, a question arose about which site acted as the active site for the enzyme and catalyzed the fumarate to malate reaction. Weaver, Lees, and Banaszak were able to determine that the A-site is the true active site of fumarase by implementing mutations on each of the sites by using E.Coli and performing PCR using recombinant DNA. The A-site histidine, which is involved in binding, is <scene name='72/725900/His_188/3'>HIS-188</scene> and the B-site histidine is <scene name='72/725900/His_129/2'>HIS-129</scene>. The experimenters expressed mutations on each of these histidine residues in separate cellular cultures by <scene name='72/725900/H188n_mutant/3'>replacing the histidine with an asparagine</scene>. They then observed how the specific activity changed for each mutated enzyme. They found that the asparagine substitution for histidine at the A-site resulted in a 200-fold decrease in specific activity of the fumarase as compared to the wild type. However, the mutation at the B-site resulted in a minimal effect on specific activity as compared to the wild type. Therefore, they concluded that the A-site, which includes HIS-188, must be the <scene name='72/725900/Active_site/2'>active site</scene> and that the B-site does not have a significant role in the catalytic ability of the enzyme <ref>PMID:9098893</ref>. |
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Revision as of 15:34, 26 February 2016
Contents |
The Active Sites of Fumarase
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is an enzyme that catalyzes the hydration/dehydration reaction that converts fumarate into malate and vice versa. After extensive experimental studies on this particular enzyme, researchers discovered fumarase has two sites that are involved in carboxylic acid binding. These sites are known as the A-site and the B-site. These two sites are both composed of hisitdine residues that act as the basic group to interact with carboxylic acids and water in their respective binding sites. However, during initial discovery of the two sites, a question arose about which site acted as the active site for the enzyme and catalyzed the fumarate to malate reaction. Weaver, Lees, and Banaszak were able to determine that the A-site is the true active site of fumarase by implementing mutations on each of the sites by using E.Coli and performing PCR using recombinant DNA. The A-site histidine, which is involved in binding, is and the B-site histidine is . The experimenters expressed mutations on each of these histidine residues in separate cellular cultures by . They then observed how the specific activity changed for each mutated enzyme. They found that the asparagine substitution for histidine at the A-site resulted in a 200-fold decrease in specific activity of the fumarase as compared to the wild type. However, the mutation at the B-site resulted in a minimal effect on specific activity as compared to the wild type. Therefore, they concluded that the A-site, which includes HIS-188, must be the and that the B-site does not have a significant role in the catalytic ability of the enzyme [1].
Function
Structural highlights
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References
1. Weaver, Todd, Mason Lees, and Leonard Banaszak. "Mutations of Fumarase That Distinguish between the Active Site and a Nearby Dicarboxylic Acid Binding Site." Protein Science 6.4 (2008): 834-42. Pub Med. Web.
