Study of a photo-induced lysozyme-riboflavin bond

Abstract

Irradiation of lysozyme in the presence of riboflavin results in the formation of a lysozyme-riboflavin adduct. Reduction and carboxymethylation of the four disulfide bonds as well as the chemical modification of the Tyr residues and the photochemical alteration of the His residue in lysozyme, do not affect the formation of the photo-induced lysozyme-riboflavin bond. When the lysozyme-riboflavin adduct was subjected to mild acid hydrolysis and ion exchange chromatography, the retention of a compound containing 14C-riboflavin was observed. Free 14C-riboflavin, on the contrary is not retained by the column. The photo-oxidation of free Trp in the presence of 14C-riboflavin, gave a compound which bound to the ion exchange resin like the above-mentioned derivative. The photo-oxidation of the Trp residues in lysozyme and in peptides obtained from lysozyme showed very high quantum yields, and these values were directly related to the incorporation of 14C-riboflavin in these samples.

Advanced Glycation Endproducts Induce Photocrosslinking and Oxidation of Bovine Lens Proteins Through Type‐I Mechanism

“…The interaction between triplet riboflavin and crystallins together with the induction of protein crosslinking at low oxygen concentration has been demonstrated (37). The amino acids susceptible to Type‐I interaction are mainly Trp, Tyr and His (42,43). Formation of Trp–Trp (44) and Tyr–Tyr (45,46) crosslinks through radical mechanisms has been observed.…”

Development of Monoclonal Antibodies Against a Riboflavin‐Tryptophan Photoinduced Adduct: Reactivity to Eye Lens Proteins*

“…The fluorescence emission remained constant in time even after the system was further exposed to the action of visible light. Once the free RF present in the irradiated BSA solution was eliminated from the medium by dialysis, it was found that the irradiated protein presented an absorption band in the region from 300 to 580 nm, which accounts for the establishment of a photochemical binding between RF and BSA (19,20).…”

“…Noteworthy, in the same region the protein matrix was less immunoreactive than toward the central region of the lens. (20). This kind of compound may also be obtained through the energy transfer from enzymatically generated excited species to R F (2 1,22).…”

“…The study of the competition between BSA-RF and Trp-RF for monoclonal antibodies to BSA-RF confirms that these monoclonal antibodies recognize an adduct between RF and i t Trp residue present in this protein. Previous studies, in which lysozyme was fractionated to its constituent peptides followed by amino acid analysis, indicated the specific binding of RF to Trp residues of this enzyme (20). Using photophysical methods, the interaction and photoinduced binding of RF to one of the Trp residues of the BSA had also heen demonstrated (3 1).…”

Triclosan–lysozyme complex: A promising antimicrobial macromolecule stable against photooxidative damage

“…The interaction between LZ and RF upon illumination generates LZ-RF adduct and photooxidation of LZ might be sensitized by RF bound to the protein and in solution (Silva & Gaule, 1977). Ferrer & Silva (1984) noted that reduction and carboxymethylation of the four disulfide bonds as well as the chemical modification of the Tyr residues and the photochemical alteration of the His residue in lysozyme, do not affect the formation of the photo-induced LZ-RF bond. However, 3 RF * can be quenched by O 2 via energy transfer to form 1 O 2 which is a strong oxidizing agent and can induce further oxidation of protein resulting in more efficient photooxidation.…”