Protein nanotubes having an inner surface wall of Candida antarctica lipase B were synthesized by alternating layer-by-layer assembly in a porous polycarbonate membrane. Scanning electron microscopy measurements revealed the formation of uniform hollow cylinders with an outer diameter of 393 +/- 9 nm. Enzymatic ring-opening oligomerization of 12-dodecanolactone was achieved in the one-dimensional pore space interior of nanotube in aqueous medium.