Open AccessExtracellular nuclease from a thermophile, Streptomyces thermonitrificans : purification and characterization of the deoxyribonuclease activity
Author(s) -
Deshmukh Sumedha S.,
Shankar Vepatu
Publication year - 2004
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.1574-6968.2004.tb09707.x
Subject(s) - nuclease , deoxyribonuclease , enzyme , biochemistry , divalent , extracellular , pyrophosphate , thermophile , streptomyces , chemistry , hydrolysis , biology , bacteria , organic chemistry , genetics
An extracellular nuclease from Streptomyces thermonitrificans (designated as nuclease Stn α) was purified to homogeneity with an overall yield of 2.8%. The M r of the purified enzyme was 39.6 kDa. The purified enzyme showed an exclusive requirement of Mn 2+ for its activity but is not a metalloprotein. The optimum pH for ds‐ and ssDNA hydrolysis were 7.0 and 7.5 whereas, the optimum temperature was 40 and 45 °C, respectively. The enzyme was inhibited by divalent cations, inorganic phosphate and pyrophosphate but not by 3′ and 5′ mononucleotides. Nuclease Stn α is a multifunctional enzyme and its substrate specificity is in the order of dsDNA > ssDNA ≫ RNA. The end products of both ds‐ and ssDNA hydrolysis were predominantly oligonucleotides (80–85%) and a small amount of 3′ mononucleotides (10–15%) suggesting an endo mode of action.