STRUCTURE OF PROTEIN-BOUND BILE PIGMENTS

具有共价结合的血红素和四吡咯辅基的蛋白质， 存在于所有生物体中并在电子传递中起重要作用， 光化学反应和代谢过程。 然而，知识 这些辅基的化学结构和立体化学 它们的多肽结合形式非常不完整。 充分表征的 红藻和蓝细菌的胆蛋白代表了 材料的结构和附着机制的研究 四吡咯辅基。 已知五种不同的四吡咯 与各种胆蛋白的多肽链共价连接，和 只有一个国家严格建立了这种结构。 先前 研究四吡咯辅基的方法包括 辅基从多肽上脱离。 这些研究 导致了对联合国结构的包容性和相互冲突的建议， 多肽连接的胆色素。 本研究采用的方法包括： 结合蛋白质降解为更简单的肽-色素， 破坏天然共价键和胆色素肽的纯化 通过温和的方法如高效液相色谱法。 的 然后直接测定纯化的胆色素-肽的结构 不需要通过高分辨率NMR进行进一步的化学操作， 通过研究适当的合成化合物。 Peptdies轴承 藻蓝胆素、藻红胆素和藻胆素组将被 考察 控制胆红素结构参数的初步研究 将进行体内与多肽的连接。 方面的方针作出 本研究中使用的方法具有普遍适用性， 蛋白质结构的不寻常方面， 改性

Proteins with covalently bound heme and tetrapyrrole prosthetic groups are present in all organisms and have important roles in electron transport, photochemical reactions, and metabolic processes. However, knowledge of the chemical structure and stereochemistry of these prosthetic groups in their polypeptide-bound forms is very incomplete. The well-characterized biliproteins of red algae and cyanobacteria represent an abundant source of material for the study of the structure and mechanism of attachment of tetrapyrrole prosthetic groups. Five different tetrapyrroles are known to be covalently linked to the polypeptide chains of various biliproteins, and in only one case has the structure been rigorously established. Previous approaches to the study of the tetrapyrrole prosthetic groups have involved detachment of the prosthetic groups from the polypeptide. These studies have led to inclusive and conflicting proposals for the structure of polypeptide-linked bilins. The approach to be used in this study involves the degradation of conjugated proteins to simpler peptide-pigments without disturbing the native covalent linkages and purification of bilin peptides by mild procedures such as high performance liquid chromatography. The structures of the purified bilin-peptides will then be determined directly without further chemical manipulation by high resolution NMR and supported by studies on appropriate synthetic compounds. Peptdies bearing phycocyanobilin, phycoerythrobilin, and phycourobilin groups will be examined. Preliminary studies of the structural parameters governing bilin attachment to polypeptide in vivo will be conducted. The approach to be utilized in this investigation has general applicability to the study of unusual aspects of protein structure introduced by post-translational modification.