Sandbox Wabash 11 Fumarase

Kyle Stucker

Fumarase C

Found in E. Coli, Fumarase C is an enzyme that catalyzes L-malate and fumarate. It belongs to a family of enzymes that includes aspartase, arginosuccinate lyase, adenlosuccinate lyase, and gamma-crysatallin. It is tetrameric and has approximately 460 amino acids in each monomer.^[1]

The Debate About Two Possible Locations of the Active Site

Many studies of Fumarase have shown that there are two different binding sites for carboxylic acid. One of the two sites is formed by the residues from three subunits and is located at the tungstate site. The active site is very deep and contains His-188, Ser-98, Thr-100, Asn-141. Site A also utilizes hydrogen bonding between a water molecule and His-188 to increase stability of substrate.^[2] The second site is formed from atoms in a single subunit and contains L-malate. Site B is close to the surface of the enzymes and is composed of Asn-131, Asp-132, His-129, and Arg-126.^[3] A study conducted by Todd Weaver, Mason Lees, and Leonard Banaszak confirmed that Site A was the actual active site by mutating the at Site A and the at Site B into and observing which mutation most effected substrate binding. The mutated was the mutation that affected activity the most. The un-mutated form of Fumarase had an activity of 4920.0 microunits/mL. When His-188 was mutated the activity of the enzyme was only at 9.62 microunits/mL, but the His-129 mutation still allowed for 2080.0 microunits/mL.^[4] These results showed that Site A was the active site.

1. ↑ Weaver T, Lees M, Banaszak L. Mutations of fumarase that distinguish between the active site and a nearby dicarboxylic acid binding site. Protein Sci. 1997 Apr;6(4):834-42. PMID:9098893
2. ↑ Weaver T, Lees M, Banaszak L. Mutations of fumarase that distinguish between the active site and a nearby dicarboxylic acid binding site. Protein Sci. 1997 Apr;6(4):834-42. PMID:9098893
3. ↑ Weaver T, Lees M, Banaszak L. Mutations of fumarase that distinguish between the active site and a nearby dicarboxylic acid binding site. Protein Sci. 1997 Apr;6(4):834-42. PMID:9098893
4. ↑ Weaver T, Lees M, Banaszak L. Mutations of fumarase that distinguish between the active site and a nearby dicarboxylic acid binding site. Protein Sci. 1997 Apr;6(4):834-42. PMID:9098893

Function

Disease

Relevance

Structural highlights

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