title: Nonfreezing Water Structuration in Heteroprotein Coacervates.
abstract: Surface-bound water in protein solutions has been identified with a reduction in its freezing point. We studied the presence of such nonfreezing water (NFW) in various protein-polyelectrolyte, micelle-polyelectrolyte, and protein-protein (heteroprotein) coacervates, along with appropriate concentrated solutions of macromolecules alone, finding up to 15% w/w NFW for the heteroprotein coacervate of lactoferrin (LF) and β-lactoglobulin (BLG). The level of NFW is always higher in coacervates than in the control (single macromolecule) systems, particularly for protein-containing coacervates: a coacervate of bovine serum albumin (BSA) and poly(dimethyldiallylammonium chloride) (PDADMAC) showed a ratio of NFW/protein twice that of BSA alone (0.6 vs 0.3), with a similarly high ratio for LF-BLG coacervate. These results are attributed to the maximization of water-protein contacts, structural features that reflect the mode of sample assembly, as they are not seen in a noncoacervated LF-BLG solution with identical concentrations of all species.
authors.affiliation: †Department of Polymer Science and Engineering and ‡Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States.
authors.forename: Xiaosong
authors.initials: X
authors.lastname: Du
authors.affiliation: †Department of Polymer Science and Engineering and ‡Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States.
authors.forename: Daniel
authors.initials: D
authors.lastname: Seeman
authors.affiliation: †Department of Polymer Science and Engineering and ‡Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States.
authors.forename: Paul L
authors.initials: PL
authors.lastname: Dubin
authors.affiliation: †Department of Polymer Science and Engineering and ‡Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States.
authors.forename: David A
authors.initials: DA
authors.lastname: Hoagland
mesh_terms: D000818:Animals; D002417:Cattle; D004573:Electrolytes / Q000737:chemistry; D007781:Lactoferrin / Q000737:chemistry*; D007782:Lactoglobulins / Q000737:chemistry*; D008823:Micelles; D015394:Molecular Structure; D011108:Polymers / Q000737:chemistry; D012710:Serum Albumin, Bovine / Q000737:chemistry*; D013499:Surface Properties; D014867:Water / Q000737:chemistry*
chemical_list: D004573:Electrolytes; D007782:Lactoglobulins; D008823:Micelles; D011108:Polymers; D014867:Water; D012710:Serum Albumin, Bovine; D007781:Lactoferrin