Carbohydrate Polymers 151 (2016) 1152–1161 Contents lists available at ScienceDirect Carbohydrate Polymers journal homepage: www.elsevier.com/locate/carbpol Formation of -carrageenan–gelatin polyelectrolyte complexes studied by 1 H NMR, UV spectroscopy and kinematic viscosity measurements Nicolay G. Voron’ko a,∗ , Svetlana R. Derkach a , Mikhail A. Vovk b , Peter M. Tolstoy b a Murmansk State Technical University, Sportivnaya str., 13, 183010 Murmansk, Russia b St. Petersburg State University, Center for Magnetic Resonance, Universitetskij pr., 26, 198504 St.Petersburg, Russia a r t i c l e i n f o Article history: Received 25 May 2016 Received in revised form 12 June 2016 Accepted 15 June 2016 Available online 16 June 2016 Chemical compounds studied in this article: -Carrageenan (PubChem CID: 11966249) Gelatin i.e. Collagen I, alpha chain (PubChem CID: 6913668) Casein (PubChem CID: 134288) Lysozyme (PubChem CID: 24839946) Chitosan (PubChem CID: 21896651) Lysine (PubChem CID: 5962) Hydroxylysine (PubChem CID: 439437) Histidine (PubChem CID: 6274) Arginine (PubChem CID: 6322) Sodium alginate (PubChem CID: 6850754) Deuterium oxide (PubChem CID: 24602) Distilled water (PubChem CID: 962) Quartz (PubChem CID: 24261) Proline (PubChem CID: 145742) Methionine (PubChem CID: 6137) Hydroxyproline (PubChem CID: 5810) Glutamic acid (PubChem CID: 611) Glycine (PubChem CID: 750) Valine (PubChem CID: 6287) Leucine (PubChem CID: 6106) Isoleucine (PubChem CID: 6306) Threonine (PubChem CID: 6288) Alanine (PubChem CID: 5950) Aspartic acid (PubChem CID: 424) Serine (PubChem CID: 5951) Phenylalanine (PubChem CID: 6140) Tyrosine (PubChem CID: 6057) Benzene (PubChem CID: 241) Keywords: -Carrageenan Gelatin (Bio)polyelectrolyte complexes High-resolution 1 H NMR spectra UV absorption spectra Viscosity a b s t r a c t The intermolecular interactions between an anionic polysaccharide from the red algae -carrageenan and a gelatin polypeptide, forming stoichiometric polysaccharide–polypeptide (bio)polyelectrolyte com- plexes in the aqueous phase, were examined. The major method of investigation was high-resolution 1 H NMR spectroscopy. Additional data were obtained by UV absorption spectroscopy, light scattering dis- persion and capillary viscometry. Experimental data were interpreted in terms of the changing roles of electrostatic interactions, hydrophobic interactions and hydrogen bonds when -carrageenan–gelatin complexes are formed. At high temperatures, when biopolymer macromolecules in solution are in the state of random coil, hydrophobic interactions make a major contribution to complex stabilization. At the temperature of gelatin’s coil → helix conformational transition and at lower temperatures, electrostatic interactions and hydrogen bonds play a defining role in complex formation. A proposed model of the -carrageenan–gelatin complex is discussed. © 2016 Elsevier Ltd. All rights reserved. ∗ Corresponding author. E-mail addresses: voronkonikolay@mail.ru (N.G. Voron’ko), derkachsr@mstu.edu.ru (S.R. Derkach), m.vovk@spbu.ru (M.A. Vovk), peter.tolstoy@spbu.ru (P.M. Tolstoy). http://dx.doi.org/10.1016/j.carbpol.2016.06.060 0144-8617/© 2016 Elsevier Ltd. All rights reserved.