Preparation and properties of alginate lyase modified with poly(ethylene glycol)

Modification of the enzyme alginate lyase (AL) with poly(ethylene glycol) (PEG) was attempted for the degradation and removal of alginate biofilms in infectious diseases. The modification of AL with PEG was attempted with three kinds of N-succinimidyl succinate PEG (SS-PEG), which differed in molecular weight (i.e., 2000, 5000 and 12,000 Da). The conjugation of PEG to free amino groups on AL was confirmed by gel permeation chromatography. Quantification of residual free amino groups revealed that PEG modification progressed further with a higher pH and a larger molar ratio of SS-PEG to AL. The reproducibility of the reaction was fairly good. The enzyme activity decreased with increasing PEG modification but the immunoreactivity toward anti-AL antibodies, as evaluated by an ELISA method, was much more remarkably reduced. The immunoreactivity was more reduced by the conjugated PEG with the larger molecular weight. In the reaction with PEG of molecular weight 12,000 Da, we obtained PEG-modified AL retaining approximately 40% enzyme activity but only 0.5% of the immunoreactivity of native AL.