Nagy J O, Bishop J E, Klotz A V, Glazer A N, Rapoport H
J Biol Chem. 1985 Apr 25;260(8):4864-8.
Three unique bilin peptides, a beta subunit peptide bearing a doubly linked phycourobilin (PUB), and two gamma subunit peptides with singly linked PUB groups, were obtained by enzymatic degradation of Gastroclonium coulteri R-phycoerythrin. These peptides were shown to have the sequences (Klotz, A. V., and Glazer, A. N. (1985) J. Biol. Chem. 260, 4856-4863): (Formula: see text) The sequence of peptide beta-3T was identical to that previously established for a doubly linked phycoerythrobilin (PEB) peptide derived from a B-phycoerythrin (Lundell, D. J., Glazer, A. N., DeLange, R. J., and Brown, D. M. (1984) J. Biol. Chem. 259, 5472-5480). Secondary ion mass spectrometry of beta-3T yielded a protonated molecular ion of 1629 mass units, the same as that given by the doubly linked PEB peptide (Schoenleber, R. W., Lundell, D. J., Glazer, A. N., and Rapoport, H. (1984) J. Biol. Chem. 259, 5481-5484), indicating that the doubly linked PUB and PEB tetrapyrroles were isomeric structures. High resolution 1H NMR analyses of peptides beta-3T, gamma-BV8, and gamma-DP provided unambiguous structural assignments for the singly and doubly linked PUB chromophores and indicated that the peptides in gamma-BV8 and gamma-DP were linked to ring A. The determination of which peptide fragment is linked to ring A and which to ring D in peptide beta-3T was not achieved in this study. 1H NMR analyses of three PEB-peptides from G. coulteri R-phycoerythrin--alpha-1 Cys(PEB)-Tyr-Arg, alpha-2 Leu-Cys(PEB)-Val-Pro-Arg, and beta-1 Met-Ala-Ala-Cys(PEB)-Leu-Arg--showed that they were identical to previously described corresponding chromopeptides from Porphyridium cruentum B-phycoerythrin, with the peptide linked to ring A of PEB in each instance (Schoenleber, R. W., Lundell, D. J., Glazer, A. N., and Rapoport, H. (1984) J. Biol. Chem. 259, 5485-5489). This is the first documented report on the structure of singly or doubly linked phycourobilins.
通过对库尔特氏海鞘红藻R - 藻红蛋白进行酶促降解，获得了三种独特的胆青素肽，一种带有双连接藻尿胆素（PUB）的β亚基肽，以及两种带有单连接PUB基团的γ亚基肽。这些肽的序列如下（克洛茨，A. V.，和格拉泽，A. N.（1985年）《生物化学杂志》260卷，4856 - 4863页）：（分子式：见正文）肽β - 3T的序列与先前从B - 藻红蛋白衍生的双连接藻红胆素（PEB）肽所确定的序列相同（伦德尔，D. J.，格拉泽，A. N.，德兰格，R. J.，和布朗，D. M.（1984年）《生物化学杂志》259卷，5472 - 5480页）。β - 3T的二次离子质谱产生了一个质量为1629质量单位的质子化分子离子，与双连接PEB肽给出的相同（舍恩勒伯，R. W.，伦德尔，D. J.，格拉泽，A. N.，和拉波波特，H.（1984年）《生物化学杂志》259卷，5481 - 5484页），表明双连接的PUB和PEB四吡咯是异构结构。对肽β - 3T、γ - BV8和γ - DP进行的高分辨率1H NMR分析为单连接和双连接的PUB发色团提供了明确的结构归属，并表明γ - BV8和γ - DP中的肽与A环相连。本研究未确定肽β - 3T中哪个肽片段与A环相连，哪个与D环相连。对库尔特氏海鞘红藻R - 藻红蛋白的三种PEB肽——α - 1半胱氨酸（PEB） - 酪氨酸 - 精氨酸、α - 2亮氨酸 - 半胱氨酸（PEB） - 缬氨酸 - 脯氨酸 - 精氨酸和β - 1甲硫氨酸 - 丙氨酸 - 丙氨酸 - 半胱氨酸（PEB） - 亮氨酸 - 精氨酸——的1H NMR分析表明，它们与先前描述的来自紫球藻B - 藻红蛋白的相应发色肽相同，且每种情况下肽都与PEB的A环相连（舍恩勒伯，R. W.，伦德尔，D. J.，格拉泽，A. N.，和拉波波特，H.（1984年）《生物化学杂志》259卷，5485 - 5489页）。这是关于单连接或双连接藻尿胆素结构的首次文献报道。
