title: Influence of tyrosine-derived moieties and drying conditions on the formation of helices in gelatin.
abstract: The single and triple helical organization of protein chains strongly influences the mechanical properties of gelatin-based materials. A chemical method for obtaining different degrees of helical organization in gelatin is covalent functionalization, while a physical method for achieving the same goal is the variation of the drying conditions of gelatin solutions. Here we explored how the introduction of desaminotyrosine (DAT) and desaminotyrosyl tyrosine (DATT) linked to lysine residues of gelatin influenced the kinetics and thermodynamic equilibrium of the helicalization process of single and triple helices following different drying conditions. Drying at a temperature above the helix-to-coil transition temperature of gelatin (T > T(c), called v(short)) generally resulted in gelatins with relatively lower triple helical content (X(c,t) = 1-2%) than lower temperature drying (T < T(c), called v(long)) (X(c,t) = 8-10%), where the DAT(T) functional groups generally disrupted helix formation. While different helical contents affected the thermal transition temperatures only slightly, the mechanical properties were strongly affected for swollen hydrogels (E = 4-13 kPa for samples treated by v(long) and E = 120-700 kPa for samples treated by v(short)). This study shows that side group functionalization and different drying conditions are viable options to control the helicalization and macroscopic properties of gelatin-based materials.
authors.affiliation: Center for Biomaterial Development and Berlin-Brandenburg Center for Regenerative Therapies, Helmholtz-Zentrum Geesthacht, Kantstrasse 55, 14513 Teltow, Germany.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Zaupa
authors.forename: Axel T
authors.initials: AT
authors.lastname: Neffe
authors.forename: Benjamin F
authors.initials: BF
authors.lastname: Pierce
authors.forename: Ulrich
authors.initials: U
authors.lastname: Nöchel
authors.forename: Andreas
authors.initials: A
authors.lastname: Lendlein
mesh_terms: D003890:Desiccation; D005780:Gelatin / Q000737:chemistry*; D007700:Kinetics; D017433:Protein Structure, Secondary; D013816:Thermodynamics; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry*
chemical_list: D014443:Tyrosine; D005780:Gelatin