Triosephosphate Isomerase: Difference between revisions
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'''Triosephosphate isomerase''' is a key enzyme in the glycolytic pathway, which catalyzes the interconversion of dihydroxyacetone phosphate ([http://en.wikipedia.org/wiki/DHAP DHAP]) and (''R'')-glyceraldehyde-3-phosphate ([http://en.wikipedia.org/wiki/Glycerate_3-phosphate GAP]). The remarkable specificity and catalytic power of the enzyme has inspired intensive studies using structural biology, biophysics, and computer simulations. TIM is a [http://en.wikipedia.org/wiki/Catalytically_perfect_enzyme catalytically perfect enzyme] in the sense that its kcat/Km value is in the diffusion-limited range, and because catalytic efficiency is not improved by changes to the chemical composition of the solvent, or by changes to the amino acid sequence of the enzyme. TIM has been estimated to lower the activation energy of the reaction by 11-13 kcal/mol. | '''Triosephosphate isomerase''' is a key enzyme in the glycolytic pathway, which catalyzes the interconversion of dihydroxyacetone phosphate ([http://en.wikipedia.org/wiki/DHAP DHAP]) and (''R'')-glyceraldehyde-3-phosphate ([http://en.wikipedia.org/wiki/Glycerate_3-phosphate GAP]). The remarkable specificity and catalytic power of the enzyme has inspired intensive studies using structural biology, biophysics, and computer simulations. TIM is a [http://en.wikipedia.org/wiki/Catalytically_perfect_enzyme catalytically perfect enzyme] in the sense that its kcat/Km value is in the diffusion-limited range, and because catalytic efficiency is not improved by changes to the chemical composition of the solvent, or by changes to the amino acid sequence of the enzyme. TIM has been estimated to lower the activation energy of the reaction by 11-13 kcal/mol. | ||
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'''Active site features''' | '''Active site features''' | ||
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'''Why is the enzyme an obligate dimer?''' | '''Why is the enzyme an obligate dimer?''' | ||
An interdigitating loop (residues 71-77) is found on each subunit. The loop extends from one subunit into a pocket near the active site of the other subunit. Notably, there is a hydrogen bond network involving Lys12 and Glu97 of one subunit and Thr75 of the other subunit. This may | An interdigitating loop (residues 71-77) is found on each subunit. The loop extends from one subunit into a pocket near the active site of the other subunit. Notably, there is a hydrogen bond network involving Lys12 and Glu97 of one subunit and Thr75 of the other subunit. This may explain why the dimer is required for catalytic activity. | ||
=References= | =References= | ||