39B-11

I. OROZCO and R. BRIONES-MARTíNEZ. Biotecnología/Enzimología, Centro de Desarrollo de Productos Bióticos, COFAA, Instituto Politécnico Nacional, Yautepec, Mor, 62730, Mexico

JUSTIFICATION: Cuaguayote (Nahuatl name for Pileus mexicanus) is a plant located in various regions of México. The fruits latex is rich in a potent cysteinic proteinase: mexicain. We have shown that mexicain has potential for food proteins processing (plant and fish protein hydrolysis). On the other hand, some groups have shown recently that other Caricaceae latex, papaya (Carica papaya) latex particularly, has a good activity in the hydrolysis of tributyroylglycerol and long-chain triacylglycerols. Because of the importance of lipase activities in food processing, our current interest is focused on the research of these enzyme activities in cuaguayote latex.

OBJECTIVE: Our goal was to search for lipase activity in Pileus mexicanus latex.

METHODS: Fresh cuaguayote latex samples were collected at our experimental plantation in Morelos, México. A dispersion was prepared from freeze dried latex and it was obtained the soluble content by centrifugation at 1000 g. The supernatant was separated in a Sephadex G-75 column. The lipolytic activity was measured titrimetrically using a pH-stat instrument. The hydrolysis rates were derived from the initial slopes of the kinetic curves and expressed as international units (IU). One IU corresponding to 1 mM of butyric acid liberated for min. The hydrolysis rate was monitored at pH 8.0 using olive oil and tributyrin as substrates.

RESULTS: The homogenate from freeze dried latex has a lypolitic activity of 3.2 IU mg-1; after centrifugation it was detected activity in both phases, the soluble and the particulate fraction: 1.76 and 4.19 IU mg-1, as measured with olive oil, respectively; and 2.16 and 7.98 IU mg-1, measured with tributyrin, respectively. By Sephadex G-75 separation of soluble fraction, two peaks were identified: the first with 856 and the second with 321 IU mg-1.

SIGNIFICANCE: The lipase activity detected suggests that P. mexicanus latex has potential as a lipolytic activity source.