Fructosyltransferase from A. aculeatus

Scheme 11.1 Transfructosylation and hydrolytic reactions catalyzed by fructosyltransferase from A aculeatus.

The fructosyltransferase from A. aculeatus displayed activity without the addition of any metal ions. However, some effects were observed in its susceptibUity to mono- and divalent cations [33]. For ejample, Mn, K, and Co caused a 1.4—1.9-fold increase in the activity, whereas low concentrations of Hg and Zn produced 35-60% inhibition. It was also found that the enzyme was slightly activated by several non-ionic and anionic surfactants such as sodium dodecylsulphate (1.5-fold at lOmM), sodium deoxycholate (1.4-fold at ImM), and Triton X-100 (1.4-fold at 5% w/v). Moreover, it was resistant to low concentrations (1-lOmM) of reducing agents such as dithiothreitol and P-mercaptoethanol. 

Figure 11.2 Kinetic plots (initial rate versus sucrose concentration) of fructosyltransferase from A aculeatus. Transfer activity ( ) and hydrolytic activity (o). Reactions were carried out in 0.2 M sodium acetate buffer (pH 5.5) at 60°C. Kinetic parameters were calculated estimating a molecular mass of 135 kDa for the active enzyme. Adapted from Ref [33].

Efficient Fructooligosaccharide Synthesis with a Fructosyltransferase from Aspergillus aculeatus... 

Table 11.1 Alignment of N-terminal amino acid sequences from A. aculeatus and A. niger fructosyltransferases and invertases.

Ghazi, L, Segura, A. G., Fernandez-Arrojo, L., Alcalde, M., Yates, M., Rojas-Cervantes, M. L., Plou, F. J. Ballesteros, A. (2005). Immobilisation of fructosyltransferase from Aspergillus aculeatus on epoxy-activated Sepabeads EC for the synthesis of fructo-oligosaccharides. Journal of Molecular Catalysis B Enzymatic, 35, 19-23. 

The fructosyltransferase mined from the commercial preparation Pectinex Ultra SP-L is quite stable towards pH, temperature, and the presence of chemicals. The A aculeatus fructosyltransferase showed a high transferase hydrolase raho that provides it with great potential for oligosaccharide synthesis. The enzyme can be easily immobilized on epoxy-activated supports for better performance. Further studies are required to draw mechanishc conclusions on the nature of the kinetics observed with this fructosyltransferase. 

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