The physiological role of BioH is to remove the methyl group introduced by BioC when the pimeloyl moiety is complete. It allows to synthesize pimeloyl-ACP via the fatty acid synthetic pathway through the hydrolysis of the ester bonds of pimeloyl-ACP esters. Also displays a weak thioesterase activity. Can form a complex with CoA, and may be involved in the condensation of CoA and pimelic acid into pimeloyl-CoA, a precursor in biotin biosynthesis. 6-carboxyhexanoyl-[ACP] methyl ester + H2O = 6-carboxyhexanoyl-[ACP] + H(+) + methanol Cofactor biosynthesis; biotin biosynthesis. Monomer. Belongs to the AB hydrolase superfamily. Carboxylesterase BioH family.