SDS-PAGE analysis of the purification of native chitinase by chitin binding. Proteins were separated on a 4 to 20% T polyacrylamide gel and silver stained. Lanes: 1, molecular mass standards (with masses given in kilodaltons); 2, unbound P. aeruginosa soluble protein extract; 3 to 5, 200 mM sodium phosphate buffer (pH 7.0) washes 1, 2, and 3, respectively; 6, 70% (vol/vol) ethylene glycol wash of chitin; 7, proteins remaining bound to chitin following elution with 70% (vol/vol) ethylene glycol.