|Budget Amount *help
¥1,400,000 (Direct Cost : ¥1,400,000)
Fiscal Year 1996 : ¥1,400,000 (Direct Cost : ¥1,400,000)
To investgate the function of the protein, it is essential to obtain the information about its structure. NMR technology is suitable to analyze the detail structure of the protein binding prosthetic group at the state of solution. In this study, we investgated the interaction between the protein structure and its physico-chemical characters, such as redox potential or dissociation constant, by determining the higher structure of FMN-binding protein using NMR spectroscopy.
We clearified that the higher structure of FMN-binding protein is different from that of flavodoxin, a well-studied protein binding FMN,by analyzing non-labelled, and ^<15>N and/or^<13>C labelled FMN-binding protein. The region of 31Thr-Trp-Asn, which is only identical region to the sequence of some flavodoxins, isn't located close to isoalloxazine ring of FMN,although it is important to binding FMN at the case of flavodoxin. Some aromatic groups of the peptide chain of FMN-binding protein are formed the array from isoalloxazine ring, and it is suggested that it may influence the redox potential and reactivity. The phosphate group of FMN is exposed to the surface of the molecule at the case of FMN-binding protein while it is buried and interacted with some atoms inside of the peptide chain of flavodoxin. These results support the characters of mutants using site-directedmutagenesis. To bind FMN,the Trp32 residue is important at the point of its bulkiness or aromaticness although Thr31 and Asn33 residue is not so important. All 9 mutants are not so much different each other at the point of redox potential except for observation of redox reaction of dissociated FMN at some mutants. We are now studying the minimum region to bind FMN or the determining region of redox potential or reactivity.