Disclosed are uses of microproteins preferably microproteins forming a cystine knot (i.e. belonging to the family of inhibitor cystine knot (ICK) polypeptides) or polynucleotides encoding said microproteins for the preparation of a pharmaceutical composition for treating or preventing a disease that can be treated or prevented by inhibiting the activity of tryptase as well as corresponding methods of treatment. Also disclosed are uses of the microproteins for inhibiting tryptase activity, for purifying tryptase, as a carrier molecule for tryptase and for deleting or quantifying tryptase in a sample, including corresponding diagnostic applications. Furthermore disclosed are fusion proteins comprising an inactive barnase as well as fusion proteins comprising barnase and a microprotein. Also encompassed are nucleic acid molecules encoding such a fusion protein, as well as corresponding vectors, host cells, preparation methods and uses of the fusion protein. Moreover, the present application discloses a crystal of a microprotein fused with barnase, preferably inactive barnase. The disclosure also refers to corresponding preparation methods for the crystal, structure analysis methods using the crystal data storage media comprising the structure data obtained, as well as to in silico methods using the structure data for characterizing the binding of microproteins to target molecules. Furthermore, disclosed are pharmaceutical compositions comprising the crystal and corresponding medical uses.