title: Self-organization of oligopeptides obtained on dissolution of feather keratins in superheated water.
abstract: Keratins are self-organized proteins that are abundantly available in wool, feather, human hair, etc., making them a potential cheap feedstock for the modification of amino acids. This paper explores the hydrolysis of keratin in water under specific pressure-temperature conditions where the hydrolysis through scission of the protein chain yields oligopeptides. Here we report for the first time that, under appropriate conditions, these oligopeptides self-assemble into a hierarchical architecture, the process being followed in time by optical microscopy. Birefringent needle-like crystals are observed which tend to nucleate heterogeneously. When given sufficient time, these needles become tens of microns in length and act as further nuclei, developing a highly repetitive structure of several hundreds of microns in size. Micro-focus X-ray diffraction studies supported by in situ microscopy reveal that these needles have a crystal structure similar to that of the native protein, although better organized along the ab-plane. Spectroscopic studies on these structures show crystalline bands that disappear above 150 degrees C, coinciding with an endothermic peak in DSC. Amino acid analysis shows that the self-assembled birefringent entities are indeed oligopeptides, consisting of sequences of approximately 40 amino acids. The proposed ecofriendly route provides an effective route for obtaining oligopeptides that can be used as important building blocks for the synthesis of a range of novel polymers. The oligopeptides obtained from the sustainable source can be used as important building blocks for the synthesis of a range of novel polymers.
authors.affiliation: Department of Chemical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600MB Eindhoven, The Netherlands.
authors.forename: Jie
authors.initials: J
authors.lastname: Yin
authors.forename: Sanjay
authors.initials: S
authors.lastname: Rastogi
authors.forename: Ann E
authors.initials: AE
authors.lastname: Terry
authors.forename: Crisan
authors.initials: C
authors.lastname: Popescu
mesh_terms: D000596:Amino Acids / Q000737:chemistry; D000818:Animals; D001671:Biochemistry / Q000379:methods*; D002645:Chickens; D005241:Feathers / Q000378:metabolism; D006868:Hydrolysis; D007633:Keratins / Q000737:chemistry*; D046911:Macromolecular Substances; D009842:Oligopeptides / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry; D011312:Pressure; D013696:Temperature; D014867:Water / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D000596:Amino Acids; D046911:Macromolecular Substances; D009842:Oligopeptides; D011108:Polymers; D014867:Water; D007633:Keratins