title: Sucrose, sodium dodecyl sulfate, urea, and 2-mercaptoethanol affect the thermal inactivation of R-phycoerythrin.
abstract: Thermal inactivation kinetics (D- and z-values) of the algal protein, R-phycoerythrin (R-PE), were studied under different buffer conditions (pH 4.0, 7.0, and 10.0) and concentrations of sucrose, sodium dodecyl sulfate (SDS), urea, and 2-mercaptoethanol (ME). R-PE solutions were heated in capillary tubes at temperatures between 40 and 90 degrees C depending on buffer conditions. Thermal inactivation parameters for R-PE, calculated on the basis of fluorescence loss, were modified by addition of chemicals. Overall, sucrose and ME had a thermostabilizing effect, while SDS and urea decreased thermal stability of R-PE. The z-values ranged from 5.9 degrees C in 50 mM NaCl, 20 mM glycine buffer, pH 10.0, to 37.8 degrees C in 60% sucrose, 50 mM NaCl, 20 mM phosphate buffer, pH 7.0. The z-values obtained for R-PE closely matched the z-values of some target microorganisms in food processes, suggesting R-PE might be used as a time-temperature integrator to verify thermal processing adequacy.
authors.affiliation: Department of Food Science and Human Nutrition, Michigan State University, East Lansing 48824-1224, USA.
authors.forename: A
authors.initials: A
authors.lastname: Orta-Ramirez
authors.forename: J E
authors.initials: JE
authors.lastname: Merrill
authors.forename: D M
authors.initials: DM
authors.lastname: Smith
mesh_terms: D005453:Fluorescence; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D008623:Mercaptoethanol / Q000494:pharmacology; D010799:Phycoerythrin / Q000096:biosynthesis* / Q000187:drug effects*; D012967:Sodium Dodecyl Sulfate / Q000494:pharmacology; D013395:Sucrose / Q000494:pharmacology; D013696:Temperature; D013997:Time Factors; D014508:Urea / Q000494:pharmacology
chemical_list: D010799:Phycoerythrin; D012967:Sodium Dodecyl Sulfate; D013395:Sucrose; D008623:Mercaptoethanol; D014508:Urea