Sequence Dependent Self-Assembly of Silk Peptides

Traditionally, silk finds its applications in textile industry. However, owing to its properties such as mechanical strength, biodegradation, biocompatibility and ease of functionalisation, silk has found its application in all walks of life of tissue engineering, textiles and drug delivery ¹. Silk is an intrinsically disordered protein that tends to form fibrilar aggregates in response to shear stress, pH, salts and dehydration ². At amino acid level, less is known about the self- assembly process of silk ^2,3. The basic objective of this work is to understand the effect of amino acid substitution on self –assembly of silk-derived peptides. For this study, small aliphatic amino acids were substituted with aromatic amino acids such as phenylalanine. In contrast to silk proteins, native and/or reconstituted, which forms fibres ^2,4, phenylalanine ⁵ has propensity to form hollow tubes. The process of self- assembly of the silk-derived peptides was monitored using THT assay, FT-IR and AFM.

References

(1) Koh, L.-D.; Cheng, Y.; Teng, C.-P.; Khin, Y.-W.; Loh, X.-J.; Tee, S.-Y.; Low, M.; Ye, E.; Yu, H.-D.; Zhang, Y.-W.et al. Structures, mechanical properties and applications of silk fibroin materials. Progress in Polymer Science 2015, 46, 86.

(2) Lu, Q.; Zhu, H.; Zhang, C.; Zhang, F.; Zhang, B.; Kaplan, D. L. Silk Self-Assembly Mechanisms and Control From Thermodynamics to Kinetics. Biomacromolecules 2012, 13 (3), 826.

(3) Partlow, B. P.; Bagheri, M.; Harden, J. L.; Kaplan, D. L. Tyrosine Templating in the Self-Assembly and Crystallization of Silk Fibroin. Biomacromolecules 2016, 17 (11), 3570.

(4) Shimanovich, U.; Ruggeri, F. S.; De Genst, E.; Adamcik, J.; Barros, T. P.; Porter, D.; Müller, T.; Mezzenga, R.; Dobson, C. M.; Vollrath, F. Silk micrococoons for protein stabilisation and molecular encapsulation. Nature Communications 2017, 8.

(5) Adler-Abramovich, L.; Reches, M.; Sedman, V. L.; Allen, S.; Tendler, S. J. B.; Gazit, E. Thermal and Chemical Stability of Diphenylalanine Peptide Nanotubes:  Implications for Nanotechnological Applications. Langmuir 2006, 22 (3), 1313.