Wemmer D E, Wedemayer G J, Glazer A N
Department of Chemistry, Lawrence Berkeley Laboratory, University of California, Berkeley 94720.
J Biol Chem. 1993 Jan 25;268(3):1658-69.
Cryptomonad strain IVF2 phycoerythrin 555 carries phycoerythrobilins attached through single thioether bonds at alpha-Cys-18, beta-Cys-82, and beta-Cys-158 and a doubly linked 15,16-dihydrobiliverdin (DBV) at beta-DiCys-50,61 (for sequence numbering, see Sidler, W., Nutt, H., Kumpf, B., Frank, G., Suter, F., Brenzel, A., Wehrmeyer, W., and Zuber, H. (1990) Biol. Chem. Hoppe-Seyler 371, 573-547). Analysis of the beta-DiCys-50,61-linked DBV by 1H homonuclear and 1H-13C heteronuclear NMR spectroscopy establishes that the thioether bond from Cys-50 is to the 3"-carbon of the DBV ring A and that from Cys-61 is to the 18'-carbon of ring D, i.e. the peptide-linked bilin is an 8,12-bis(2-carboxyethyl)-3-(2-(cysteinyl-S)-ethyl)-18-(1-(cysteinyl-S)-e thyl)- 2,7,13,17-tetramethylbiladiene-ab-1,19(16H,21H)-dione. DBV is also present at beta-DiCys-50,61 in cryptomonad strain UW374 phycocyanin 645 (Wedemayer, G. J., Kidd, D. G., Wemmer, D. E., and Glazer, A. N. (1992) J. Biol. Chem. 267, 7315-7331). NMR spectroscopy shows that the thioether bonds to this DBV are also at 3" and 18'. Linkage of tetrapyrroles to polypeptides through the 3"-carbon has not hitherto been reported.
隐甲藻菌株IVF2藻红蛋白555在α - Cys - 18、β - Cys - 82和β - Cys - 158位点通过单硫醚键连接藻红素胆素，并在β - DiCys - 50,61位点连接一个双连接的15,16 - 二氢胆绿素（DBV）（关于序号编号，见Sidler, W., Nutt, H., Kumpf, B., Frank, G., Suter, F., Brenzel, A., Wehrmeyer, W., and Zuber, H. (1990) Biol. Chem. Hoppe - Seyler 371, 573 - 547）。通过1H同核和1H - 13C异核NMR光谱对β - DiCys - 50,61连接的DBV进行分析表明，来自Cys - 50的硫醚键连接到DBV环A的3'' - 碳上，来自Cys - 61的硫醚键连接到环D的18'' - 碳上，即肽连接的胆素是8,12 - 双（2 - 羧乙基）- 3 - （2 - （半胱氨酰 - S）- 乙基）- 18 - （1 - （半胱氨酰 - S）- 乙基）- 2,7,13,17 - 四甲基胆二烯 - ab - 1,19(16H,21H)- 二酮。DBV也存在于隐甲藻菌株UW374藻蓝蛋白645的β - DiCys - 50,61位点（Wedemayer, G. J., Kidd, D. G., Wemmer, D. E., and Glazer, A. N. (1992) J. Biol. Chem. 267, 7315 - 7331）。NMR光谱表明，与该DBV的硫醚键也在3''和18''位置。迄今为止，尚未报道过四吡咯通过3'' - 碳与多肽的连接。
