Purification and Characterization of Four Extracellular Proteases Isolated from Raw Milk Psychrotrophs

摘要: Abstract Extracellular proteases from psychrotrophic strains of Bacillus coagulans (LY 9), sp. 10), subtilis 11), and Pseudomonas fluorescens 13) were purified characterized. The molecular weight the protease LY 13 was 4.50×10 4 , three species ranged 3.35×10 to 3.90×10 . 10 monomeric proteins, whereas 9 in a polymeric form that contained up 14 subunits. Only showed trypsin-like activity. All four inhibited by ethylenediaminetetraacetate would be classified as metallo proteases. Casein preferred substrate for these Susceptibility casein fractions attack varied with enzyme source. Maximum activity between pH 6.5 7.5. retained more after heating at 63°C 30min than species. Calcium ion protective effect decreasing heat denaturation 11. This tended greater presence Tris-HC1 buffer (.05 M 7.5) plus 10% skim milk only.