The activity and crystal stability of the enzyme thiosulfate sulfurtransferase were studied as a function of ionic strength. At 2 M ammonium sulfate, where the x-ray structural studies of this protein were done soluble enzyme has low activity (<16% of the activity of the enzyme at an ionic strength of 0.1) and crystals of the enzyme are stable when substrates are added. However, at 1.4 M ammonium sulfate, crystals of TST rapidly dissolve in 1 mM CN- but are relatively stable in 1 mM S2O3=. These results are consistent with a conformational change on converting the sulfur substituted form of the enzyme (ES) to the sulfur-free form (E) and helps to explain why this change was not observed in the crystallographic studies.
|Original language||English (US)|
|Number of pages||5|
|Journal||Biochemical and Biophysical Research Communications|
|State||Published - May 30 1980|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology