Vervoort J, O'Kane D J, Müller F, Bacher A, Strobl G, Lee J
Department of Biochemistry, Agricultural University, HA Wageningen, The Netherlands.
Biochemistry. 1990 Feb 20;29(7):1823-8. doi: 10.1021/bi00459a023.
The interaction between the prosthetic group 6,7-dimethyl-8-(1'-D-ribityl)lumazine and the lumazine apoproteins from two marine bioluminescent bacteria, one from a relatively thermophilic species, Photobacterium leiognathi, and the other from a psychrophilic species, Photobacterium phosphoreum, was studied by 13C and 15N NMR using various selectively enriched derivatives. It is shown that the electron distribution in the protein-bound 6,7-dimethyl-8-ribityllumazine differs from that of free 6,7-dimethyl-8-ribityllumazine in buffer. The 13C and 15N chemical shifts indicate that the protein-bound 6,7-dimethyl-8-ribityllumazine is embedded in a polar environment and that the ring system is strongly polarized. It is concluded that the two carbonyl groups play an important role in the polarization of the molecule. The N(3)-H group is not accessible to bulk solvent. The N(8) atom is sp2 hybridized and has delta+ character. Nuclear Overhauser effect studies indicate that the 6,7-dimethyl-8-ribityllumazine ring is rigidly bound with no internal mobility. The NMR results indicate that the interaction between the ring system and the two apoproteins is almost the same.
利用各种选择性富集衍生物，通过碳-13和氮-15核磁共振研究了辅基6,7-二甲基-8-(1'-D-核糖基)蝶啶与两种海洋发光细菌的蝶啶脱辅基蛋白之间的相互作用，其中一种来自相对嗜热的物种——日本发光杆菌，另一种来自嗜冷物种——磷光发光杆菌。结果表明，与蛋白质结合的6,7-二甲基-8-核糖基蝶啶中的电子分布与缓冲液中游离的6,7-二甲基-8-核糖基蝶啶不同。碳-13和氮-15化学位移表明，与蛋白质结合的6,7-二甲基-8-核糖基蝶啶嵌入在极性环境中，且环系统强烈极化。得出的结论是，两个羰基在分子极化中起重要作用。N(3)-H基团无法与大量溶剂接触。N(8)原子为sp2杂化且具有δ+特性。核Overhauser效应研究表明，6,7-二甲基-8-核糖基蝶啶环紧密结合，没有内部流动性。核磁共振结果表明，环系统与两种脱辅基蛋白之间的相互作用几乎相同。
