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Primary structure of human triosephosphate isomerase
The Journal of Biological Chemistry
|October 10, 1984
Summary
Researchers purified human placental triosephosphate isomerase (TPI) to unprecedented specific activity. This allowed detailed primary structural analysis, revealing a conserved dimeric structure and evolutionary stability in TPI across species.
Area of Science:
- Biochemistry
- Molecular Biology
- Enzymology
Background:
- Triosephosphate isomerase (TPI) is a crucial enzyme in glycolysis.
- Understanding TPI's structure is vital for metabolic pathway research.
- Previous studies lacked detailed primary structural information for human placental TPI.
Purpose of the Study:
- To isolate and purify human placental triosephosphate isomerase (TPI) with high specific activity.
- To determine the primary amino acid sequence of human placental TPI.
- To compare the human TPI sequence with homologous enzymes from other species.
Main Methods:
- Improved enzyme isolation and purification techniques.
- Enzyme reduction, carboxymethylation, and enzymatic digestion (tryptic, chymotryptic).
- High-performance liquid chromatography (HPLC) for peptide separation.
- High-sensitivity solid-phase sequencing for primary structure determination.
Main Results:
- Human placental TPI was purified to the highest specific activity reported.
- The enzyme is a dimer of two identical 248-amino acid subunits (26,750 Da each).
- High sequence homology was observed between human TPI and TPI from rabbit, chicken, and coelacanth.
- Active-site and subunit contact residues showed minimal evolutionary changes.
Conclusions:
- The study provides the complete primary structure of human placental TPI.
- The high sequence homology indicates conservative evolution of TPI across diverse species.
- Key functional sites, including the active site, are highly conserved, underscoring their importance.