The research proposed in this project application complements ongoing activities on the use of chitooligosaccharides (CHOS) as environmentally friendly fungicides. CHOS inhibit chitinases, enzymatic systems that allows fungi to grow. The project focuses o n chemical approaches to production of functionalized CHOS, including the use of combinatorial chemistry. We have already set up for testing of anti-fungal activity, design, production and application of chitinases and other enzymes for the conversion of chitin and chitosan to CHOS, and advanced studies of enzyme-ligand interactions using techniques such as mass spectrometry of non-covalent complexes, isothemral titration calorimetry and surface plasmon resonance. Naturally, isolated CHOS will have their anti-fungal activity enhanced through modifications of functional groups. Especially, increasing the hydrophobicity of the CHOS and introducing point charges will increase the binding strength to chitinases since these to strategies are common for all en zyme ? ligand systems. Hydrophobicity will be introduced through the addition of fatty acids and alky chains. Point charges will originate from charged groups such as phosphates, sulphates, carboxylates, and quarternay amines. Screening of modified, stron g binding CHOS will take place by a newly developed method by our research group. The mixture of CHOS will be incubated with desired chitinases and the strongest binding CHOS will be detected as an enzyme ? ligand complex using mass spectrometry, and the structure of the CHOS will be determined by performing a top-down analysis in an MS-MS experiment. The strong binding CHOS will be purified using both size exclusion chromatography and affinity chromatography.