Volume 55 (2005) Issue: 2005 No#2-3

Extracellular proteinases in natural isolates of staphylococci

Author(s): Fira Đ, Begović Jelena, Topisirović LJ

Keywords:casein, inhibitors, proteinases, Staphylococcus

Biochemical characteristics of proteinases from natural isolates of Staphylococcus sp. F22, F86, M104, S2007 and S2105 have been studied. It was found that these proteinases have relatively low molecular masses (from 20 to 32 kDa), and that they are released from the cell envelope in to the growth medium. Their temperature optima are between 30 and 37OC and their pH optima range from 6,5 to 8. Copper ions inhibit their activity, but the presence of calcium ions stimulates the activity of proteinases from isolates F22, M104 and S2007. Beside casein fractions, they also hydrolyze heterologous protein substrates, such as BSA and gelatin. Experiments with specific proteinase inhibitors revealed that proteinases from isolates F22 and M104 belong to the serine group of proteinases, S2007 and S2105 proteinases were classified as metalloproteinases. Type of F86 proteinase in these experiments could not be clearly determinated.