A new fluorescent probe for the study of the allosteric properties of D-glyceraldehyde 3-phosphate dehydrogenase.

ion, this displacement is accomodated in the DPI molecule by a corresponding movement of the imidazole ring. As mentioned above, the two phenylalanine residues B24 and B25 are important for the biological activity of insulin. Fig. 9 shows the change in conformation of these two residues in DPI compared with insulin (molecule I). We can see that a large change in conformation occurs at B25, while B24 is in a very similar position in both molecules. From these results we would like to think that both the chemical properties and the precise conformation of B24 are important for biological activity, while perhaps the chemical properties of B25 are more important than its conformation. We hope that the important biological significance of the C-terminal region of the B-chain of insulin, particularly B24 and B25, will be further clarified by the solution of the DHPI and des-octapeptide-insulin structures.