Provided are an optimized Der f2 gene, a recombinant Der f2 protein encoded thereby, a vector comprising said gene, and a Pichia pastoris strain. Also provided are an expression method, a purification method, and an application of the recombinant Der f2 protein.

Provided is a structural protein microbody that functions as a core for forming a protein nanofiber. There is provided a structural protein microbody including a structural protein, in which the structural protein microbody satisfies at least two of the following (i) to (iii): (i) a peak is present within a range of 480 to 500 nm in a fluorescence intensity measurement by thioflavin T staining; (ii) a peak is present in a region where Q is 0.15 or less in a modified Kratky plot of small angle X-ray scattering (SAXS); and (iii) the structural protein microbody is an aggregate of two or more structural protein molecules.

Disclosed herein are compositions and methods of use comprising peptides that bind to ion channels. Such peptides can function as active agents that target ion channels to inhibit or activate ion channels in a target tissue or cell type. In some embodiments, such peptides can be conjugated to another active agent or a detectable label.

Provided are an optimized Der f2 gene, a recombinant Der f2 protein encoded thereby, a vector comprising said gene, and a Pichia pastoris strain. Also provided are an expression method, a purification method, and an application of the recombinant Der f2 protein.