NMR Study of Insect Adipokinetic Hormones

Abstract

Mem-CC (pGlu-Leu-Asn-Tyr-Ser-Pro-Asp-Trp-NH₂), Tem-HrTH (pGlu-Leu-Asn-Phe-Ser-Pro-Asn-Trp-NH₂) and Del-CC (pGlu-Leu-Asn-Phe-Ser-Pro-Asn-Trp-GIy-Asn-NH₂) are adipokinetic hormones, isolated from the corpora cardiaca of different insect species. These hormones regulate energy metabolism during flight and so are intimately involved in an insect's mobility. In an attempt to measure the solution conformations of these peptides, their ₁H nmr spectra have been recorded in dimethylsulfoxide solution. the N7 analogue, [N7]-Mem-CC (pGlu-Leu-Asn-Tyr-Ser-Pro-Asn-Trp-NH₂) has also been studied. the solution dynamics of Tem-HrTH has been simulated in dmso and in a water droplet. These results have been correlated with measured coupling constants. the molecule was found to have a (β-turn at proline with asparagine (N7), which is postulated to be involved in receptor binding and/or activation, projecting outward from the turn.

Key Words:

• AKH peptides
• Mem-CC, [N7]-Mem-CC
• Tem-HrTH, Del-CC