(3R)-hydroxybutanoate dimer + (R)-3-hydroxybutanoate + H(+) => (3R)-hydroxybutanoate trimer + H2O
(3r)-hydroxybutanoate dimer + (r)-3-hydroxybutanoate + h(+) => (3r)-hydroxybutanoate trimer + h2o
(3R)-hydroxybutanoate dimer + (R)-3-hydroxybutanoate + H(+) => (3R)-hydroxybutanoate trimer + H2O
(3r)-hydroxybutanoate dimer + (r)-3-hydroxybutanoate + h(+) => (3r)-hydroxybutanoate trimer + h2o