Investigating the Effect of X -Ray and UV light on the conjugation of Lysozyme with Dextran

The radiation damage (X-ray, UV light) of many proteins and other biomolecules has been investigated by various physicochemical techniques. These studies have revealed numerous changes in the local and global structure of the proteins studied, together with alterations of their functional abilities, such as inactivation, aggregation, fragmentation, destruction of aromatic amino acids and disulfide bonds, formation of crosslinks and new chromophores, partial unfolding, etc. X-irradiation radiolysis products of water (OH•-, O2•- and H2O2), are the true reactants and UV light can also produce reactive free radical. Lysozyme has been subjected to many radio and photobiological treatments, particularly aiming at the damage mechanics. The aims of this study was to investigate the possibility of using X-ray and UV light to create new stable covalent bond between dextran and lysozyme and to monitor the structural changes incurred in the conjugated products. Lysozyme and dextran were mixed with a weight ratio 1 to 5 in phosphate buffer (pH=7.4). Sample were exposed to UV-C light (250 – 280 nm) for 4 hours. Another sample was exposed to X-ray (50 KeV) for 0.04 sec. The lytic activity of all treated samples was reduced compared to the control (no treatment) sample. However, no significant changes was observed in the SDS- PAGE pattern of all samples. Our data suggests that both X-ray and UV light cause structural changes in lysozyme but, unlike other physical treatments such as heat or microwave, do not bring about significant degree of conjugation.

کلیدواژه ها:

Lysozyme ، Dextran ، X-ray ، UV light ، Conjugation