Laccase-catalyzed cross-linking of BSA mediated by tyrosine

Tyrosine was explored as a cross-linking agent to form cross-linked bovine serum albumin (BSA) using laccase catalyst. Liquid chromatography-mass spectrometry (LC-MS) and fluorescence spectra indicated that tyrosine can be mainly oxidized dityrosine. Spectra analysis molecular weight were used characterize the BSA treated with laccase. Both SDS-PAGE size exclusion chromatography confirmed formation of BSA, while most protein products existed BSA–tyrosine conjugates. The MALDI-TOF revealed five units grafted on one monomer, however consists two monomers 18 tyrosine. Furthermore, content amino acid identified analysis, among those percentage lysine presented visible decline from 12.36% 11.43%, corresponding 4–5 residues. pure modified hydrolyzed by trypsin peptides obtained. Different mass LC-MS after hydrolysis could react Lys-136, Lys-204, Lys-224, Lys-322 Lys-537 in promoting conjugates BSA.