OIL BODIES OF TRANSGENIC BRASSICA-NAPUS AS A SOURCE OF IMMOBILIZED BETA-GLUCURONIDASE

The process of immobilizing enzymes is a major cost factor in the util ization of heterogeneous catalysts on an industrial scale. We have dev eloped a new strategy, based on plant genetic manipulation, for the pr oduction of foreign peptides associated with the oil body in plant see ds. Seeds of transgenic rapeseed can be produced on a large scale al r elatively low cost. Furthermore, oil bodies are readily isolated from seeds by floatation centrifugation. In this paper, we describe some ph ysical and operational properties of an oil body-fusion protein comple x and its suitability as a heterogeneous catalyst. Oil bodies from rap eseed, corn, and flax aggregate at PH 5, which facilitates their recov ery by floatation. Oil bodies from transgenic rapeseed, carrying the r eporter gene beta-glucuronidase or the pharmaceutical peptide, hirudin , also aggregate in the same range. This aggregation is reversible. Oi l bodies are resistant to a wide range of pH, with some lysis occurrin g (<10%) at the extremes. They are resistant to shearing forces, such as stirring. The thermal and pH stabilities, as well as the catalytic activity of beta-glucuronidase expressed on the oil body surface, are comparable to those of free beta-glucuronidase enzyme.