Enzyme PEG Conjugates - An enzyme L- asparaginase (isolated from microbes) has antitumour properties, but is toxic with a life time of less then 18hr thus reducing its utility. It has been shown that E. coli L­-asparaginase can be modified by polyethylene glycol derivatives to produce PEG-asparaginase conjugates , which differ from the native enzyme in following features:
(i) it retains only 52% of the catalytic activity of native enzyme;
(ii) it becomes resistant to proteolytic degradation; (Hi) it does not cause allergy. In view of this, PEG-asparaginase has been used to treat malignant murine (mouse), canine (cats, etc.) and human tumours. PEG conjugates of a large number of enzymes (adenosine deaminase, uricase, catalase, etc.) have been prepared and will be utilized in industry also.