Stoll M S, Vicker N, Gray C H, Bonnett R
Biochem J. 1982 Jan 1;201(1):179-88. doi: 10.1042/bj2010179.
Evidence is presented which supports the postulate that the photobilirubins IIA and IIB are diastereoisomers in which the C-3 vinyl group has cyclized intramolecularly. The evidence comes principally from proton n.m.r. spectroscopy at 400 MHz and from chemical considerations. The cyclic structures require the E-configuration at the C-4 double bond in the precursor; this is the first structural evidence for the Z leads to E isomerization in bilirubin and supports the view that the precursor (photobilirubin IA or IB) is (4E, 15Z)-bilirubin. Brief irradiation of photobilirubin II gives bilirubin, a new compound (photobilirubin III) and unchanged starting material. The various photoisomers are discussed in terms of their inter-relationships and biological fates.
光胆红素IIA和IIB是非对映异构体，其中C-3乙烯基已在分子内环化。证据主要来自400MHz的质子核磁共振光谱和化学方面的考虑。环状结构要求前体中C-4双键处为E构型；这是胆红素中Z向E异构化的首个结构证据，并支持前体（光胆红素IA或IB）是(4E, 15Z)-胆红素的观点。光胆红素II的短暂照射产生胆红素、一种新化合物（光胆红素III）和未变化的起始原料。根据它们之间的相互关系和生物学归宿对各种光异构体进行了讨论。
