Ordered Self-assembly of a Glycine-rich Linear and Cyclic Hexapeptide: Contrasting Ultrastructural Morphologies of Fiber Growth

Abstract

Self-assembly is a widely occurring phenomenon in chemistry and biology, where nanoscopic building blocks are organized to yield well-defined aggregates and supramolecular structures. One such example is ordered protein aggregation, which is primarily driven by hydrogen bonding, hydrophobic interactions and other non-covalent stabilizing factors. This report describes differing ultrastructural morphologies of a cyclic and linear hexapeptide, possessing the same amino acid sequence. Microscopic studies reveal two dissimilar pathways leading to self-assembly: one with spherical pre-fibrillar intermediate, while another one displaying spherulite-like “Maltese-cross” patterns. Detailed analysis provides crucial insight into initiation, propagation and growth of peptide fibers in two constructs.

Keywords:

• Peptide
• Aggregation
• Self-assembly
• Conjugate
• Ultrastructure

Acknowledgements

KBJ thanks IIT-Kanpur for a graduate fellowship. Authors thank Prof. Ashutosh Sharma, Chemical Engineering, and ACMS, IIT-Kanpur, for microscopic facilities. This work is supported by a Swarnajayanti Fellowship to SV from Department of Science and Technology, India.