Amyloid like Property of Large Protein Fibers & its application as a Biomaterial

Abstract

Amyloids are protein fibrillar aggregates which possess a definite cross β structure providing them rigidity and resistant against cleavage by proteases. The orientation of the β strands corresponding to the axis of the β sheets is what gives them there characteristic cross β architecture. The occurrences of amyloids are implicated in diseases like Alzheimer’sand Parkinson’s where the tissue functionality is turned inactive due to protein aggregation.However, natural conditions like In Skin Melanosomes and In Pituitary the peptide hormones are seen to have amyloid conformations.In nonmammalian sources like Curli proteins in the biofilm of E.coli, APLP2 proteins in xenopus and spider silk also possess amyloid like conformation. The specific modulus of amyloid is comparable to steel and the ease of amyloid preparation which is also cost effective makes them a prospective biomaterial like Silk Amyloids are prepared from different protein sources invitro subjected to various physiological conditions.
Keeping in view of these aspects we prepared amyloid from Pepsin which is reported. The reason for selecting pepsin is their ability to form denatured aggregated fibrils at the physiological pH of the body. In this study preparation of large amyloid fibers from pepsin is reported. Proteins are known for emulsifying capacity in food industry. Amyloids are structures possessing exposed β sheet arrangement keeping in view of such morphology we evaluated its role as an emulsifier.The emulsion stability was assessed using inverted tube assay and centrifugation. Such a property of amyloids if optimized can be used efficiently as lipophilic drug delivery agent.

Spider silk is reported to be a structural sub-class of amyloid cross β conformation. In domain of such finding we assessed the structural conformation of three kinds of wasp nest fibers (Common wasp,Yellow Jacket wasp and Mud dauber wasp). The overall structural morphology and the protein secondary structure distribution were observed and was compared to that of amyloid. The findings suggested that the nest fibers may possess some amyloid like conformation due to their Thioflavin T binding property but also the presence high number of native β sheets proposes some unique secondary structure arrangement like silk.Biocompatibility of the materials were performed which included MTT Assay and Hemolysis Assay.To evaluate their possible role as biomaterials in bone tissue engineering Alkaline Phosphatase Activity, Glycosaminoglycan secretion and Cell adhesion study were also carried out. The findings proposed that like Natural Silk the Natural Wasp Fibers can also be used as a future biomaterial for tissue engineering.