A BIOCHEMICAL-COMPARISON BETWEEN LATEX FROM CARICA-CANDAMARCENSIS ANDC-PAPAYA

1. A group of plant proteinases is present mainly in the unripe fruit of the papaya tree (Carica papaya), which is a member of the genus Car ica. C. candamarcensis is another species that belongs to this group. Its latex contains several proteinases displaying high proteolytic act ivity. 2. We used several electrophoretic techniques to compare the pr otein composition of the latex from the two species. Acid electrophore sis followed by staining or Western blot revealed a total of 17 protei ns in C. candamarcensis and 7 proteins in C. papaya. Some of the prote ins observed in C, papaya have been previously reported in the literat ure. 3. Electrophoresis on denaturing gels, followed by staining or We stern blot revealed the presence of 14 proteins in C. candamarcensis a nd 6 proteins in C. papaya. Non-equilibrium isoelectrofocusing of the latex from both species showed a larger array of proteins in C. candam arcensis. The analysis of esterase and proteolytic activities on gel f ractions after electrophoresis revealed the presence of distinct areas presenting enzyme activity. Some proteins detected in C. candamarcens is have different mobilities when compared with proteins from C. papay a. 4. These results support the view that latex from C. candamarcensis contains a wider diversity of proteins compared to C. papaya, and tha t some of the proteins not in C, papaya present esterase and proteolyt ic activity.