Spatial structure of the fibril-forming SEM1(86-107) peptide in a complex with dodecylphosphocholine micelles

The SEM1(86-107) peptide is a fragment of the semenogelin 1 protein, a component of human semen coagulum. The peptide is known to form amyloid fibrils, which increase the infectious activity of the human immunodeficiency virus. In the present work, we determined the spatial structure of the SEM1(86-107) peptide in an aqueous solution containing dodecylphosphocholine (DPC) micelles by NMR spectroscopy. It was found that the peptide has a disordered structure with a 3(10)-helix turn (fragment 94T-96S). Despite a disordered structure of the peptide, it was possible to distinguish fragments with good convergence in the ensemble (87L-92K, 94T-97Q, and 104Q-107L). A comparison of the obtained structure with the data on the structure of the SEM1(86-107) peptide in an aqueous solution in the absence of DPC micelles showed that the presence of DPC micelles in an aqueous solution led to the emergence of a helical fragment of the SEM1(86-107) peptide and the change in the distribution of hydrophilic fragments of the molecule.

Automated summary

The SEM1(86-107) peptide has a disordered structure with a 3(10)-helix turn in an aqueous solution containing DPC micelles. Despite its disorder, specific fragments with good convergence were identified. The presence of DPC micelles led to the emergence of a helical fragment and changes in the distribution of hydrophilic fragments of the peptide.