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Biochemical and Structural Characterization of the Carbohydrate Transport Substrate-binding-protein SP0092
Published on: October 2, 2017
Structural Stability of Streptococcal Serum Opacity Factor
Dedipya Yelamanchili1, Baiba K Gillard1,2, Antonio M Gotto1,2
1The Center for Bioenergetics and Metabolism, Houston Methodist Research Institute, 6670 Bertner St., Houston, TX, 77030, USA.
The Protein Journal
|April 5, 2017
Summary
Streptococcal serum opacity factor (SOF) is a stable protein that reduces plasma cholesterol by affecting high density lipoprotein (HDL). Its activity depends on pH and ionic strength, crucial for its interaction with HDL.
Area of Science:
- Biochemistry
- Microbiology
- Protein Chemistry
Background:
- Streptococcal serum opacity factor (SOF) is a protein known to destabilize high density lipoprotein (HDL) in mammalian plasma.
- SOF administration in mice leads to a significant reduction in plasma cholesterol levels.
Purpose of the Study:
- To investigate the stability of SOF under various conditions.
- To determine how pH, ionic strength, temperature, and guanidinium chloride (GdmCl) affect SOF's stability and its reaction rate with HDL.
Main Methods:
- SOF stability was assessed by pre-incubation at different temperatures, pH values, and GdmCl concentrations.
- Reaction rates were measured under varying GdmCl concentrations, pH, and ionic strengths at standard conditions (pH 7.4, 37°C).
Main Results:
- SOF demonstrated remarkable stability, retaining activity up to 58°C, across pH 4-10, and even after exposure to 8.5 M GdmCl.
- SOF activity was inhibited by GdmCl ≥ 1 M.
- Optimal SOF activity occurred at pH 5 and an ionic strength of 3 (NaCl), correlating with its isoelectric point.
Conclusions:
- SOF is a robust protein with significant stability across a wide range of environmental conditions.
- The protein's interaction with HDL and subsequent activity are influenced by factors affecting its net charge, such as pH and ionic strength.
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