Einar Mantyla

Barley as a green factory for the production of functional Flt3 ligand

Biologically active recombinant human Flt3 ligand was expressed and isolated from transgenic barley seeds. Its expression is controlled by a tissue specific promoter that confines accumulation of the recombinant protein to the endosperm tissue of the seed. The recombinant Flt3 ligand variant expressed in the seeds contains an HQ‐tag for affinity purification on immobilized metal ion affinity chromatography (IMAC) resin. The tagged protein was purified from seed extracts to near homogeneity using sequential chromatography on IMAC affinity resin and cation exchange resin. We also show that the recombinant Flt3 ligand protein undergoes posttranslational modifications: it is a glycoprotein containing α‐1,3‐fucose and α‐1,2‐xylose. The HQ‐tagged Flt3 ligand variant exhibits comparable biological activity to commercial Flt3 ligand. This is the first report showing expression and accumulation of recombinant human growth factor in barley seeds with a yield of active protein similar to a bacterial expression system. The present results demonstrate that plant molecular farming is a viable approach for the bioproduction of human‐derived growth factors.

Isolation, Characterization and Utilization of Psychrophilic Proteinases from Atlantic Cod

A mixture of psychrophilic proteolytic enzymes, called Cryotin, has been prepared from a neutral extract of pyloric caeca from Atlantic cod Gadus morhua. This proteinase mixture has many unique characteristics. The proteinases, studied so far, are more active at low temperatures, when compared to their mammalian counterparts. They are also unusually thermo-labile as well as acid labile. Cryotin has been shown to contain trypsin, chymototrypsin, elastase and a collogenolytic enzyme, as well as other proteolytic and peptidolytic activities, but it is practically devoid of lipase, amylase and nuclease activities.