Isomaltose formation

The initial overall reaction rate (sucrose consumption rate) decreases considerably with higher initial glucose concentration (Fig. 2), whereas the isomaltose formation rate increases up to 300 g L 1 glucose, which reflects the shift from dextran formation (substrate reaction) to the acceptor reaction (Fig. 3). However, with increasing glucose concentration, the maximal reaction rate shifts towards higher initial sucrose concentrations. However sucrose concentrations >0.5 M inhibit the reaction (Fig. 3). 

Fig. 3 Initial isomaltose formation rates with soluble dextransucrase (1.32 U mL"1) at different glucose and sucrose concentrations. Filled circles. 100 g L 1 glucose open triangles 300 g L-1 glucose filled squares 500 g L 1 glucose...

In order to evaluate dextransucrase operational stability during isomaltose formation, enzyme half-lives were investigated over extended time of operation with the given parameters of the reaction over 6 h. The decrease of enzyme activity E as a function of time may be described by a first order reaction ... 

Berensmeier S, Jordening H-J, Buchholz K (2006) Isomaltose formation by free and immobilised dextransucrase. Biocata Biotrans 24 280-290... 

Recently isomaltose, as a singular product, has gained interest, so its formation by dextransucrase will be discussed in more detail in this chapter. Optimal reaction conditions were elaborated in this project for isomaltose production in a pilot reactor, including the following steps [15] ... 

Some commercial, glucoamylase-containing preparations also contain a transglucosylase that catalyzes the formation of isomaltose. The net result is a lower degree of conversion of starch into D-glucose. Removal of the transglucosylase makes higher conversions possible. 

The main drawback associated with the use of glucoamylase is the formation of reversion products, particularly isomaltose this necessitates taking some care in interpretation of results. Although this reaction... 

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