Triose Phosphate Isomerase Structure & Mechanism: Difference between revisions
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==Triose Phosphate Isomerase (TIM)== | ==Triose Phosphate Isomerase (TIM)== | ||
===General Information=== | |||
Triose phosphate isomerase (TIM)<ref>PMID:16511037</ref><ref>PMID:8061610</ref> (PDB [[1wyi]] and [[1hti]]) is a crucial enzyme in the glycolytic pathway. <scene name='Christian_Krenk_Sandbox/Nc_rainbow/1'>TIM</scene> reversibly converts the aldose Glyceraldehyde-3-phosphate (GAP) to the ketose Dihydroxyacetone phosphate (DHAP). The interconversion proceeds by an enediol intermediate. Triose phosphate isomerase is not directly regulated, but the enzyme two steps before it in the glycolytic pathway, phosphofructokinase, is a heavily regulated, irreversible enzyme. | Triose phosphate isomerase (TIM)<ref>PMID:16511037</ref><ref>PMID:8061610</ref> (PDB [[1wyi]] and [[1hti]]) is a crucial enzyme in the glycolytic pathway. <scene name='Christian_Krenk_Sandbox/Nc_rainbow/1'>TIM</scene> reversibly converts the aldose Glyceraldehyde-3-phosphate (GAP) to the ketose Dihydroxyacetone phosphate (DHAP). The interconversion proceeds by an enediol intermediate. Triose phosphate isomerase is not directly regulated, but the enzyme two steps before it in the glycolytic pathway, phosphofructokinase, is a heavily regulated, irreversible enzyme. | ||
===Structural Characteristics | ===Structural Characteristics=== | ||
The secondary structure consists of 14 alpha helices and 8 beta sheets per monomer, making it fall in the SCOP category of alpha and beta proteins. The tertiary structure is a <scene name='Christian_Krenk_Sandbox/Alpha_beta_barrel/2'>alpha-beta barrel.</scene> | The secondary structure consists of 14 alpha helices and 8 beta sheets per monomer, making it fall in the SCOP category of alpha and beta proteins. The tertiary structure is a <scene name='Christian_Krenk_Sandbox/Alpha_beta_barrel/2'>alpha-beta barrel.</scene> | ||
The quaternary structure is a homodimer. The molecular weight of the enzyme is estimated at 57,400 Da.<ref>PMID:752201</ref> | The quaternary structure is a homodimer. The molecular weight of the enzyme is estimated at 57,400 Da.<ref>PMID:752201</ref> | ||
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===Mechanism | ===Mechanism=== | ||
The enzyme aids in catalysis by binding tightly to the enediol transition state. To convert GAP to the enediol intermediate, a proton is abstracted from C2 by a base and the carbonyl oxygen atom is protonated by an acid.<ref>Voet, Donald, Judith G. Voet, and Charlotte W. Pratt. Fundamentals of Biochemistry Life at the Molecular Level. New York: John Wiley & Sons, 2008. p. 495. Print.</ref> | The enzyme aids in catalysis by binding tightly to the enediol transition state. To convert GAP to the enediol intermediate, a proton is abstracted from C2 by a base and the carbonyl oxygen atom is protonated by an acid.<ref>Voet, Donald, Judith G. Voet, and Charlotte W. Pratt. Fundamentals of Biochemistry Life at the Molecular Level. New York: John Wiley & Sons, 2008. p. 495. Print.</ref> | ||