N-DEGLYCOSYLATION OF FRUCTOSYLTRANSFERASE AND INVERTASE FROM FUSARIUM-OXYSPORUM DECREASES STABILITY BUT HAS LITTLE EFFECT ON KINETICS AND SYNTHETIC SPECIFICITY

Most of the carbohydrate moiety of invertase and fructosyltransferase (FTF) from F. oxysporum IMI 172464 was removed by peptide-N-glycosidas e F. The molecular weights of native invertase and FTF were 260 kDa an d 210 kDa respectively. Deglycosylation lowered the molecular sizes by 42% and 23%, respectively. The K-m values for sucrose remained unchan ged by deglycosylation. However the stability of both enzymes at their optimum pH (4.0 for invertase, 5.0 for FTF) and optimum temperature ( 45 degrees C for invertase, 35 degrees C for FTF) was decreased: their sensitivity to protease digestion was increased by 36% and 41%, respe ctively. The synthetic specificity of deglycosylated FTF remained unch anged. The carbohydrate moiety of invertase and FTF contributes to the stability of the enzymes but is not essential in their catalytic func tion and plays no part in determining their specificity.