(4Z,15Z)-bilirubin IXalpha C8,C12-beta-D-bisglucuronoside + UDP => (4Z,15Z)-bilirubin IXalpha C12-beta-D-glucuronoside + UDP-alpha-D-glucuronate
(4z,15z)-bilirubin ixalpha c8,c12-beta-d-bisglucuronoside + udp => (4z,15z)-bilirubin ixalpha c12-beta-d-glucuronoside + udp-alpha-d-glucuronate