USE OF A CYSTEINE PROTEINASE FROM CARICA-CANDAMARCENSIS AS A PROTECTIVE AGENT DURING DNA EXTRACTION

We describe the use of a plant cysteine proteinase isolated from latex of Carica candamarcensis as a protective agent during isolation of ba cterial DNA following growth in culture of these cells. Between 100 to 720 units of proteinase (1 mu g = 6 units) afforded good DNA protecti on when incubated with various kinds of microorganisms. Agarose gel el ectrophoresis showed that the resulting DNA was similar in size to DNA preparations obtained by treatment with proteinase K. The viability o f the resulting material was checked by PCR amplification using specie s-specific primers. After standing at room temperature (25 degrees C) for 35 days, the enzyme lost 10% of its initial activity. The enzyme s tability and good yield of DNA suggest the use of this proteinase as a n alternative to proteinase K.