The gene encoding a peptidase that belongs to the proteinase K family of serine peptidases has been identified from a psychrotrophic Serratiasp., and cloned and expressed inEscherichia coli. The gene has 1890 base pairs and encodes a precursor protein of 629 amino acids with a theoretical molecular mass of 65.5 kDa.

Proteins from organisms living in extreme conditions are of particular interest because of their potential for being templates for redesign of enzymes both in biotechnological and other industries. The crystal struc-ture of a proteinase K-like enzyme from a psychrotroph Serratiaspecies has been solved to 1.8 A˚ .