title: Trypsin and trypsin inhibitor bind milk beta-lactoglobulin: Protein-protein interactions and morphology.
abstract: Conjugation of trypsin and trypsin inhibitor with milk beta-lactoglobulin (b-LG) was studied in aqueous solution at physiological pH. Multiple spectroscopic methods and transmission electron microscopy (TEM) were used to characterize protein-protein interactions and protein morphology. Thermodynamic analysis ΔH (-24 to -11kJMol-1),ΔS (-30 to -5JMol-1K-1) and ΔG (-12 to -10kJMol-1) showed that protein-protein interactions occur via H-bonding and van der Waals contacts. The binding affinity was trypsin>trypsin inhibitor with Ktrypsin-b-LG=9.8 (±1)×104M-1and Ktrypsininhibitor-b-LG=7.5 (±0.7) x 103M-1. Transmission electron microscopy showed major changes in protein morphology upon protein-protein interactions.
authors.affiliation: Department of Chemistry-Biochemistry and Physics, University of Québec at Trois- Riviéres C. P. 500, Trois-Rivières, Québec, G9A 5H7, Canada.
authors.forename: P
authors.initials: P
authors.lastname: Chanphai
authors.affiliation: Department of Chemistry-Biochemistry and Physics, University of Québec at Trois- Riviéres C. P. 500, Trois-Rivières, Québec, G9A 5H7, Canada. Electronic address: heidar-ali.tajmir-riahi@uqtr.ca.
authors.forename: H A
authors.initials: HA
authors.lastname: Tajmir-Riahi
mesh_terms: D000818:Animals; D002417:Cattle; D007782:Lactoglobulins / Q000378:metabolism*; D008892:Milk / Q000737:chemistry*; D011485:Protein Binding; D013816:Thermodynamics; D014357:Trypsin / Q000378:metabolism*; D014361:Trypsin Inhibitors / Q000378:metabolism*
chemical_list: D007782:Lactoglobulins; D014361:Trypsin Inhibitors; D014357:Trypsin
keywords: Beta-lactoglobulin; Conjugation; Spectroscopy; TEM; Trypsin; Trypsin inhibitor