Biosynthesis and properties of an extracelluar metalloprotease from the Antarctic marine bacterium Sphingomonas paucimobilis

An extracelluar protease from the marine bacterium Sphingomonas paucimobilis, strain 116, isolated from the stomach of Antarctic krill, Euphausia superba Dana, was purified and characterized. The excretion of protease was maximal at temperatures from 5 to 10 degree C, i.e. below the temperature optimum for the strain growth (15 degree C). The highly purified enzyme was a metalloprotease [sensivity to ethylenediaminetetraacetic acid (EDTA)] and showed maximal activity against proteins at 20-30 degree C and pH 6.5-7.0, and towards N-benzoyl-tyrosine ethyl ester (BzTyrOEt) at pH 8.0. At 0 degree C the enzyme retained as much as 47% of maximal activity hydrolysis of urea denatured haemoglobin (Hb) (at pH 7.0), and at -5 and -10 degree C, 37 and 30%, respectively. The metalloprotease was stable up to 30 degree C for 15 min and up to 20 degree C for 60 min. These results indicate that the proteinase from S. paucimobolis 116 is a cold-adapted enzyme.