ACCEPTOR REACTIONS OF MALTODEXTRINS WITH LEUCONOSTOC-MESENTEROIDES B-512FM DEXTRANSUCRASE

The acceptor products of maltose with Leuconostoc mesenteroides B-512FM dextransucrase are panose (62-α-d-glucopyranosyl maltose) and a homologous series of 62-isomaltodextrinosyl maltoses. The structures of the acceptor products of dextransucrase with other maltodextrins, maltotriose to maltooctaose (G3-G8), were determined by using the known specificities of α-glucosidase and porcine pancreatic α-amylase, and by methylation analysis. It has been found that dextransucrase transfers a d-glucopyranosyl residue to C-6 of either the nonreducing end or the reducing end residues of the maltodextrins, G3-G8, forming an α(1 → 6) linkage. When a d-glucose was transferred to the nonreducing residue, the first product was also an acceptor to give the second product, which served as an acceptor to give the third product, etc. to give a homologous series. When d-glucose was transferred to the reducing residue, the first product did not readily serve as an acceptor to give products or it served only as a very poor acceptor to give a small amount of the next homologue. The effectiveness of maltodextrins as acceptors decreased as the size of the maltodextrin chain increased. Maltotriose was 40% as effective as maltose and maltooctaose was only 6% as effective. © 1990.