Title
Tannic acid as a precipitating agent of human plasma proteins
Author
Aline Ferreira Pinto, Jéssica Miranda do Nascimento, Renata Vitória da Silva Sobral, Elba Lúcia Cavalcanti de Amorim, Ricardo Oliveira Silva, Ana Cristina Lima Leite
Year
2019
Journal
European Journal of Pharmaceutical Sciences
Abstract
The search for plasma proteins precipitation methods has been increasing due to the plasma protein therapeutic needs in world-wide. Thus, this work evaluates the tannic acid (TA) ability to precipitate proteins from human plasma. In this study, TA-plasma protein complexes were studied at different pH conditions, tannin/plasma ratio and reaction mixing time. The complexes formed from combinations of TA and plasma proteins were analyzed by gel electrophoresis, protein quantification, particle size, charge, mass spectrometry, microscopic image, and circular dichroism. It was possible to verify the precipitate formation in all tested pH values, with high precipitation at pH 5. The native PAGE analysis showed three mainly bands corresponding independent of the pHs used. It was possible to observe a gradual growing of precipitate protein in the first precipitation process (P1) when increased the TA/plasma ratio. 15 min of incubation was enough to precipitate 72.3% of proteins. Spectroscopic analyzes showed albumin signals and the electron microscopy analysis of IgG-TA confirmed the compact form of a precipitate. According to CD, formation of the IgG-TA complexes does not cause a major structural change of the protein. From the results obtained, it was possible to establish some parameters for plasma proteins precipitation using TA.
Instrument
J-715
Keywords
Circular dichroism, Secondary structure, Antibodies, Protein stability, Pharmaceutical, Biochemistry