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Structural and stability effects of phosphorylation: Localized structural changes in phenylalanine hydroxylase
Frederico Faria Miranda1, Matthías Thórólfsson, Knut Teigen
1Department of Biomedicine, University of Bergen, 5009-Bergen, Norway.
Protein Science : a Publication of the Protein Society
|April 21, 2004
Summary
Phosphorylation of phenylalanine hydroxylase (PAH) enhances its activity and resistance to proteolysis. Molecular dynamics and biophysical methods reveal localized conformational changes, explaining these functional effects.
Area of Science:
- Biochemistry
- Enzymology
- Structural Biology
Background:
- Phenylalanine hydroxylase (PAH) is crucial for amino acid metabolism.
- PAH activity and stability are regulated by post-translational modifications like phosphorylation.
Purpose of the Study:
- To investigate the structural and functional consequences of PAH phosphorylation at Ser16.
- To elucidate the molecular mechanisms behind increased catalytic efficiency and proteolysis resistance.
Main Methods:
- Molecular dynamics simulations of phosphorylated and unphosphorylated PAH.
- Analysis of charge-charge interactions and conformational changes.
- Differential scanning calorimetry, circular dichroism, and fluorescence spectroscopy.
- Limited chymotryptic proteolysis assays.
Main Results:
- Phosphorylation at Ser16 induces localized conformational changes near the phosphorylation site and the active site.
- These changes enhance basal enzyme activity and resistance to trypsin-like proteolysis.
- Global conformational stability is unaffected, as confirmed by biophysical techniques.
Conclusions:
- PAH phosphorylation at Ser16 fine-tunes enzyme function through localized structural adjustments.
- The findings provide a molecular basis for PAH regulation by phosphorylation.
- This study deepens understanding of enzyme kinetics and protein stability.