When grown on a sucrose-containing medium, Candida utilis synthesizes and secretes two invertases: one of molecular size of 280 kDa (the S-form - Slow-migrating) and a new form of Mr of 62 kDa (the F-form - Fast-migrating). Prior to immobilization, purification of S- and F-forms of invertase increased the immobilization yield to 89-100%, in comparison with that of crude invertase preparation (52%). The immobilized purified S- and F-form of invertase remained partially active after 15 min at 100 degreesC; the F-form retained almost 30% of its maximum activity. The immobilized S- form or F-form of invertase almost completely inverted (95% hydrolysis) 60% (w/v) sucrose over 5 h continuous reaction at 80 degreesC. Moreover, at 90 degreesC the immobilized F-form hydrolysed 70% of 60% (w/v) sucrose over 5 h, while the capability of the immobilized S- form of inverting sucrose over 5 h reaction decreased from 80% to 45%.