A time-dependent, two-step binding mode of the nitro dye flavianic acid to trypsin in acid media.
Synthetic dyes bind to proteins causing selective coprecipitation of the complexes in acid aqueous solution by a process of reversible denaturation that can be used as an alternative method for protein fractionation. The events that occur before precipitation were investigated by equilibrium dialysis using bovine trypsin and flavianic acid as a model able to cause coprecipitation. A two-step mode of interaction was found to be dependent on the incubation periods allowed for binding, with pronounced binding occurring after 42 h of incubation. The first step seems to involve hydration effects and conformational changes induced by binding of the first dye molecule, following rapid denaturation due to the binding of six additional flavianate anions to the macromolecule.
Schneedorf
J M
JM
Laboratório de Fitofármacos, Faculdade de Medicina, Universidade de Alfenas, 37130-000 Alfenas MG, Brasil. jose.silva@unifenas.br
Santoro
M M
MM
Lovrien
R E
RE
Mares-Guia
M
M
D000818:Animals; D002417:Cattle; D011232:Chemical Precipitation; D004396:Coloring Agents / Q000737:chemistry*; D003956:Dialysis; D008956:Models, Chemical; D011506:Proteins / Q000032:analysis*; D013451:Sulfonic Acids / Q000737:chemistry*; D013997:Time Factors; D014357:Trypsin / Q000737:chemistry*
D004396:Coloring Agents; D011506:Proteins; D013451:Sulfonic Acids; D014357:Trypsin