CHEMICAL DERIVATIVES OF PSEUDOMONAS-AERUGINOSA ELASTASE SHOWING INCREASED STABILITY

Elastase from Pseudomonas aeruginosa has recently been used successful ly for peptide synthesis. To improve its performance we attempted to i ncrease its catalytic stability by chemical modification. Two distinct sorts of amino group-specific modifiers, dimethyl suberimidate and cy anuric chloride-activated polyethylene glycol (PEG), gave a two-fold i ncrease in catalytic stability at 70 degrees C and greater degrees of stabilization at lower temperatures. Suberimidate treatment seemed to act by intramolecular crosslinking, whereas the activated PEG gave ris e to an elastase-PEG conjugate. The thermal transition (T-m) for suber imidate-treated elastase was unchanged from the native value of 72 deg rees C. PEG-conjugated elastase gave anomalous T-m curves; therefore, a value could not be determined. The lack of correspondence of catalyt ic stabilization with increased T-m values is discussed.