NMR studies with a Varian-XL200 spectrometer have been made on the separated as well as the mixed S-thiomethyl A and B chains of insulin.Upon mixing of the chains,both of the ring proton peaks of Tyr shifted towards low field as compared with the separated chains.This can be explained either by a decrease in the ionization of Tyr or by deshielding owing to the interaction of the chains.In the meantime,the methyl proton peaks also shifted towards low field in a time dependent mode similar to that of the ring...
【基金】
This work was supported by the National Institutes of Health(Graat AM 34035—01)