Open AccessPurification and characterisation of a serine peptidase from the marine psychrophile strain PA‐43
Author(s) -
Irwin Jane A,
Alfredsson Gudni A,
Lanzetti Anthony J,
Gudmundsson Haflidi M,
Engel Paul C
Publication year - 2001
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.2001.tb10770.x
Subject(s) - phenylmethylsulfonyl fluoride , psychrophile , serine protease , serine , bacillus subtilis , biochemistry , enzyme , substrate (aquarium) , proteases , protease , biology , strain (injury) , chemistry , pmsf , bacteria , ecology , genetics , anatomy
An extracellular serine peptidase, purified from the culture supernatant of the sub‐Arctic psychrophilic bacterium strain PA‐43, is monomeric, with a relative molecular mass of 76 000, and an unusually low p I of 3.8. The peptidase is active towards N ‐succinyl AAPF p ‐nitroanilide and N ‐succinyl AAPL p ‐nitroanilide, indicating a chymotrypsin‐like substrate specificity. It is inhibited by the serine peptidase inactivator phenylmethylsulfonyl fluoride, but not by EDTA or EGTA, suggesting that added metal ions are not necessary for activity. The enzyme is most active at pH 8.3 and at 55–60°C, although it is unstable at 60°C. It is nevertheless remarkably stable for an enzyme from a psychrophilic microorganism, remaining active after 1 week at 20°C and after five freeze–thaw cycles. Comparison of the N‐terminal 40 amino acid residues with other archived sequences revealed highest similarity to the alkaline serine protease ( aprx ) from Bacillus subtilis .