Research On The Synthesis And Properties Of Cryptochrome Model Compounds

Magnetoreception is one of the most controversial of biosensing capabilities,and it has been found that more than 50 kinds of creatures can use geomagnetic field for orientation and navigation.The cryptochrome is currently the only biological magnetosensitive molecule based on chemical magnetoreception,and many studies have been carried out in this area for many years.However,due to the complex in vivo and photosensitivity of cryptochrome,it is very difficult to research directly on cryptochrome.In order to solve the problem that cryptochrome protein is not suitable,people try to use various alternative systems to research.The model compound is an important methods to research photochemical process.The magnetosensing cryptochrome model compound F10 T designed by our group has been proved to be an excellent cryptochrome model compound.However,the compound F10 T also has a problem of low yield and complicated synthesis steps,which limits the widespread use of F10 T.One the other hand,as a cryptochrome model compound,only one F10 T is too singular.So a series of model compounds should be synthesized to meet the needs of the research on the magnetoreception of cryptochrome.This paper first redesigned the synthetic scheme of the cryptochrome model compound F10 T.A suitable coupling reagent was screened on the peptide condensation step to increase the yield to 77.1%;the amino group deprotection was catalyzed by hydrogen transfer reaction using Pd/C-ammonium formate,thereby avoiding the safety and technical problems caused by the use of high pressure hydrogen gas,which is simple and rapid in reaction;it is a two-step reaction in the synthesis of formylmethyl flavin,which can be synthesized stably and reliably.Using this new synthesis scheme,we successfully obtained the target compound F10 T and increased the total synthesis yield from 3% to 7.3%.Secondly,based on the model compound F10 T,a new series of model compounds F3 T,F8T and F9 T were synthesized by using spacer arms with different carbon chain lengths.The total synthesis yields of model compounds were all about 7%.Finally,the photochemical properties and molecular structure of model compounds were studied.UV-visible spectroscopy revealed that the flavin and tryptophan components of model compounds remained relatively independent,had supramolecular properties,and had different molecular conformations in different solvents.The model compound has poor photostability,and its photolysis reaction has a characteristic of zero-order reaction characteristic in aqueous solution and a characteristic of first-order reaction characteristic in methanol solution.By analyzing the molecular orbitals of the model compounds,we theoretically explains the photoinduced electron transfer reaction of the cryptochrome model compounds from the tryptophan component to the flavin component.A series of cryptochrome model compounds synthesized in this paper,which provide a reliable alternative research system for the study of the magnetoreception of cryptochrome,and are also expected to play a role in biological magnetoreception applications.