Influence of heat and sodium dodecyl sulfate on the endopeptidase I from Bacillus sphaericus 9602.

Endopeptidase I from Bacillus sphaericus is a stable enzyme which retains its activity at 37 degrees C in the presence of sodium dodecyl sulfate. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate revealed two forms of the enzyme: an active, fast-running form, for the enzyme preheated at 37 degrees C and a denatured, slow-running form, for the enzyme preheated at 100 degrees C. Such behavior is similar to that of the "heat-modifiable" outer membrane proteins from gram-negative bacteria. In the absence of sodium dodecyl sulfate, endopeptidase I aggregated in an enzymatically active dimer, with an apparent molecular weight of 90,000 daltons, which could be the native form of the enzyme.