The L-gulono lactone oxidase (GULO) enzyme is required for the final step of L-ascorbic acid biosynthesis. Although several species are capable of synthesizing vitamin C, this enzymatic activity is lost in humans and many other animals. Elastin is an elastomeric protein that is one of the key components of the extracellular matrix which provides structural stability to bodily tissues and organs. The applications of biopolymer-based elastin and elastin-derived molecules in biomedical and drug delivery systems have been increasingly investigated due to their remarkable properties such as elasticity, self-assembly, prolonged stability and biological activity. The recombinant human elastin-like peptide (HELP) has been used as a basic material for cross-linking matrices in regenerative medicine. The project is divided into three tasks. Task 1 is devoted to preparing the expression plasmids for bacterial and plant-based production of the fusion protein. The DNA fragment encoding the full length rat GULO will be synthesized by the commercial company according to the sequence designed. Several sets of plasmids will be prepared for each production system. The expression plasmids will be introduced into the appropriate hosts (bacterial cells and plant tissues). In task 2 the crude extracts from the hosts will be used for verification of the presence of GULO-HELP, protein purification and assay of the catalytic activity of recombinant GULO enzyme. The best constructs for the stable transformation of plants will be selected for plant transformation (Task 3). It is plant species that will be transformed: arabidopsis thaliana as a model plant, and tobacco Nicotiana tabacum as a provider of a large biomass. After selection of the respective transformants the verification of recombinant protein production and assay of GULO activity will be performed.