Isolation and thermal stability studies of two novel serine proteinases from the fungus Tritirachium album Limber.

A number of serine proteinases are secreted into the culture medium when Tritirachium album Limber is supplied with protein as the only nitrogen source. From this population of proteinases, we have isolated two novel proteolytic enzymes, designated as proteinase R and T. We have compared the thermal stability of these two proteinases with that of subtilisin BPN' and proteinase K. Both of these proteinases were thermally stable in the absence of detergents in buffers of low (4.0) and high (10.0) pH. The thermal stability of proteinase T was not affected by the presence of 1.0% SDS either at pH 8.0 or 10.0 in contrast to proteinase R which became heat labile. At low pH, the presence of SDS was detrimental to the stability of all the proteinases.