[(3R)-hydroxybutanoate](n+1) + CoA => (3R)-3-hydroxybutanoyl-CoA + [(3R)-hydroxybutanoate](n)
[(3r)-hydroxybutanoate](n+1) + coa => (3r)-3-hydroxybutanoyl-coa + [(3r)-hydroxybutanoate](n)
[(3R)-hydroxybutanoate](n+1) + CoA => (3R)-3-hydroxybutanoyl-CoA + [(3R)-hydroxybutanoate](n)
[(3r)-hydroxybutanoate](n+1) + coa => (3r)-3-hydroxybutanoyl-coa + [(3r)-hydroxybutanoate](n)