Acceptor products

Research of the structures of alternansucrase acceptor products arising from D- 50... 

The final product concentration depends significantly on the ratio of substrate and acceptor. The first acceptor product (panose in the presence of maltose) is favored at high maltose in excess, further tetra- and pentasaccharides are formed in significant amounts.37 Thus isomalto-oligosaccharides (IMOS) can be produced in good yield under appropriate reaction conditions (see Section III). 

In the presence of such weak acceptors as fructose, initial overall reaction rates decrease significantly with increasing concentration of acceptor, whereas they increase with the substrate concentration. Initial rates of acceptor-product formation increase with both substrate and acceptor formation, the formation of dextran being... 

Summarizing the results of many investigations, monosaccharides and such derivatives as D-mannitol and D-glucitol are rather weak acceptors. Disaccharides, including such acceptor products as isomaltose, are much better acceptors, except for certain molecules, for instance leucrose, which is not an acceptor.29,46,47 The decrease of enzyme activity with time has been described in terms of a first-order reaction. The inactivation parameters have been calculated for the immobilized enzyme. The inactivation constants kd were 0.0135 (1/d) when maltose was the acceptor (stabilizing), and 0.029 (1/d) when fructose was the acceptor.38... 

J. F. Robyt and S. H. Eklund, Stereochemistry involved in the mechanism of action of dextransucrase in the synthesis of dextran and the formation of acceptor products, Bioorg. Chem., 11 (1982) 115-132. 

M. Dols, M. Remaud-Simeon, R. M. Willemot, M. Vignon, and P. Monsan, Structural characterization of the maltose acceptor products synthesized by Leuconostoc mesenteroides NRRL B-1299 dextransucrase, Carbohydr. Res., 305 (1998) 549-559. 

Acceptor X Glucose incorporated into acceptors X Glucose incorporated into dextran No. of acceptor products Relative acceptor efficiency ... 

Fig. Structures of some acceptor products of B-512F dextran...

Fig. 8.—Thin-layer chromatographic autoradiogram of the acceptor products formed in the reaction of B-512FM dextransucrase with [14C]sucrose and D-glucose. The first acceptor product of D-glucose is isomaltose, followed in decreasing amounts by isomaltotriose through isomaltooctaose. A small amount of leucrose results from the acceptor reaction of D-fructopyranose. Dextran remains at the origin.

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