Dextransucrase acceptor reactions

K. Heincke, B. Demuth, H. J. Joerdening, and K. Buchholz, Kinetics of the dextransucrase acceptor reaction with maltose Experimental results and modeling, Enzyme Microb. Technol., 24 (1999) 523-534. 

J. F. Robyt and T. F. Walseth, The mechanism of acceptor reactions of Leuco-nostoc mesenteroides B-512F dextransucrase, Carbohydr. Res., 61 (1978) 433 145. 

F. Paul, E. Oriol, D. Auriol, and P. Monsan, Acceptor reaction of a highly purified dextransucrase with maltose and oligosaccharides. Application to the synthesis of controlled molecular weight dextrans, Carbohydr. Res., 149 (1986) 433-441. 

A. Tanriseven and J. F. Robyt, Inhibition of dextran synthesis by acceptor reactions of dextransucrase and the demonstration of a separate acceptor binding-site, Carbohydr. Res., 225 (1992) 321-329. 

Mechanisms for the synthesis of branch linkages and for acceptor reactions of B-512F dextransucrase. 

Recently, it has been reported that a low molecular weight alternan, with lowered viscosity, can be produced by conducting the s3mthesis of alternan in the presence of D-glucose and endodextranase (23). The latter prevents the formation of dextran by contaminating dextransucrase and the former decreases the molecular size of the alternan by acceptor reactions that terminates alternan polymerization. 

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.

Robyt JF, Walseth TF (1978) The mechanism of acceptor reactions of Leuconostoc mesen-teroides B-512F dextransucrase. Carhohydr Res 61 433 145... 

Mayer RM, Matthews MM, Futerman CL, Pamaik VK, Jung SM (1981) Dextransucrase acceptor substrate reactions. Arch Biochem Biophys 208 278-287... 

Table I Quantitative Effects of Acceptors in the Dextransucrase Reaction B-512F...

Table II Quantitative Effects of a-Methyl-D-glucopyranoside Analogues as Acceptors in the B-512F Dextransucrase Reaction...

Not all of the acceptors react with equal efficiency. In a series of reactions with different acceptors with a 1 1 acceptor-to-sucrose ratio at 80 mAf, the amount of dextran formed in the reaction was determined for Leuc. mesenteroides B-512FM dextransucrase.108 Maltose was the most effective acceptor for decreasing the amount of dextran formed. Sixteen other acceptors were compared on a relative scale, with maltose defined as 100%. The next best acceptor was isomaltose (89%), followed by nigerose (58%), methyl a-D-glucopyranoside (52%), D-glucose (17%), turanose (13%), lactose (11%), cellobiose (9%), and D-fructose (6.4%). 

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