Synthesis, purification and analysis of new plant biopolymers

The impact of non-biodegradable plastics on the biosphere is one of the great problems that humankind has to face in recent years. Transgenic photosynthetic organisms, like plants or algae, may be an alternative and sustainable way to produce commercially valuable compounds, such as biodegradable polymers. Chloroplasts have often been used as bioreactors for the production of heterologous proteins for industrial applications. An engineered version of the storage protein (phaseolin) of Phaseolus vulgaris, in which a cysteine residue has been added to its C-terminal region, has been inserted in the chloroplast DNA. The protein originated polymers linked by disulfide bridges and localized in the thylakoid fraction. Phaseolin polymers were extracted from tobacco leaves and analyses to characterize their structure and properties. These polymers had a molar mass of about 1 to 20 MDa and accumulated to about 2.5 % of total soluble proteins. They could be useful in biomedical field, for example as a matrix on which to load drugs for a controlled release or as a material for the construction of biocompatible gauzes.