Monooxygenase that promotes depolymerization of F-actin by mediating oxidation of specific methionine residues on actin to form methionine-sulfoxide, resulting in actin filament disassembly and prevent repolymerization. H(+) + L-methionyl-[F-actin] + NADPH + O2 = H2O + L-methionyl-(R)-S-oxide-[F-actin] + NADP(+) H(+) + NADPH + O2 = H2O2 + NADP(+) Belongs to the Mical family.