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Transamination catalysed by tyrosine phenol-lyase from Citrobacter intermedius
T V Demidkina1, I V Myagkikh, A V Azhayev
1Institute of Molecular Biology, USSR Academy of Sciences, Moscow.
European Journal of Biochemistry
|December 30, 1987
Summary
This study reveals tyrosine phenol-lyase catalyzes an irreversible half-transamination with substrates and inhibitors, forming pyridoxamine phosphate and keto acids. This clarifies enzyme reaction mechanisms and amino group transfer direction.
Area of Science:
- Biochemistry
- Enzymology
- Protein-ligand interactions
Background:
- Tyrosine phenol-lyase is an enzyme involved in amino acid metabolism.
- Understanding its substrate and inhibitor interactions is crucial for enzyme mechanism elucidation.
Purpose of the Study:
- To investigate the interactions between tyrosine phenol-lyase and its substrates (L-tyrosine, L-serine) and inhibitors (L-alanine, L-phenylalanine, L-m-tyrosine).
- To characterize the kinetic parameters of the observed reactions.
Main Methods:
- Enzyme kinetics studies were performed.
- Identification of reaction products, including pyridoxamine phosphate and keto acids, was carried out.
Main Results:
- The enzyme was shown to catalyze a half-transamination reaction between substrates/inhibitors and pyridoxal phosphate.
- Kinetic parameters for beta-elimination and transamination were determined.
- The amino group transfer to the coenzyme was found to be irreversible.
Conclusions:
- Tyrosine phenol-lyase exhibits irreversible transamination with its substrates and inhibitors.
- The identified products provide insight into the enzyme's catalytic mechanism.