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Human L-3-phosphoserine phosphatase: sequence, expression and evidence for a phosphoenzyme intermediate
J F Collet1, I Gerin, M H Rider
1Laboratory of Physiological Chemistry, ICP and University of Louvain, Brussels, Belgium.
FEBS Letters
|May 26, 1997
Summary
Researchers identified the human L-3-phosphoserine phosphatase cDNA sequence. This enzyme, crucial for amino acid metabolism, was expressed and purified, revealing its catalytic activity and a novel phosphoryl-enzyme intermediate in its reaction mechanism.
Area of Science:
- Biochemistry
- Molecular Biology
- Enzymology
Background:
- L-3-phosphoserine phosphatase is an enzyme involved in amino acid metabolism.
- Understanding its human form is crucial for biological and medical research.
Purpose of the Study:
- To report the cDNA sequence encoding human L-3-phosphoserine phosphatase.
- To characterize the expressed human enzyme's activity and reaction mechanism.
Main Methods:
- cDNA sequencing
- Bacterial expression and protein purification
- Enzyme activity assays (hydrolysis and exchange reactions)
- Phosphorylation studies using radiolabeled substrate
Main Results:
- The human L-3-phosphoserine phosphatase cDNA encodes a 225-residue polypeptide with 30% identity to the E. coli enzyme.
- The purified human enzyme exhibits Mg2(+)-dependent catalytic activity, hydrolyzing L-phosphoserine and facilitating L-serine/L-phosphoserine exchange.
- Evidence suggests a phosphoryl-enzyme intermediate, likely involving an aspartyl- or glutamyl-phosphate, was formed during the reaction.
Conclusions:
- The study provides the sequence and functional characterization of human L-3-phosphoserine phosphatase.
- The findings elucidate key aspects of the enzyme's catalytic mechanism, including the formation of a phosphoryl-enzyme intermediate.
- This research contributes to the understanding of serine metabolism and phosphatase enzymology.