(3R)-hydroxybutanoate tetramer + (R)-3-hydroxybutanoate + H(+) => (3R)-hydroxybutanoate pentamer + H2O
(3r)-hydroxybutanoate tetramer + (r)-3-hydroxybutanoate + h(+) => (3r)-hydroxybutanoate pentamer + h2o
(3R)-hydroxybutanoate tetramer + (R)-3-hydroxybutanoate + H(+) => (3R)-hydroxybutanoate pentamer + H2O
(3r)-hydroxybutanoate tetramer + (r)-3-hydroxybutanoate + h(+) => (3r)-hydroxybutanoate pentamer + h2o