We describe the modification of the side chain of the arginine-B22 residue of insulin by the N8N9-(1, 2-dihydroxycyclohex-1,2-ylene) group and by the adipoyl group. These are the first insulin derivatives described that contain a modified arginine residue in an otherwise unaltered molecule. When tested for their ability to lower blood sugar concentration, both modified insulins showed a specific activity indistinguishable from that of insulin. In view of the fact that the substituent groups involved are very bulky and in one case of opposite charge to that of the side chain, the retention of biological activity casts doubt on the idea, previously generally accepted, that the arginine-B22 residue is essential to the activity of the hormone.
