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Chain Length Specifity of Cyclodextrin Glycosyltransferase
Author(s) -
Vetter Dirk,
Thorn Werner
Publication year - 1992
Publication title -
starch ‐ stärke
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.62
H-Index - 82
eISSN - 1521-379X
pISSN - 0038-9056
DOI - 10.1002/star.19920440608
Subject(s) - cyclodextrin , chemistry , yield (engineering) , moiety , maltose , acceptor , oligosaccharide , stereochemistry , enzyme , chromatography , biochemistry , materials science , physics , metallurgy , condensed matter physics
Bacillus macerans CGTase recognizes the terminal 6 glucose units of the non‐reducing end of α‐(1→4)‐glucans. Analysis of the chain‐length distributions produced by the action of CGTase on well‐defined maltodextrins gave information on the enzyme's specifity in regard of the size of the transferred glucanosyl‐moiety. It was found that in the presence of α‐cyclodextrin, maltohexaosyl‐groups could be highly specifically coupled to an acceptor like maltose. The product, maltooctaose, appeared in a yield of 45 % molar amount. The affinity for hexaosylresidues was explored by using homodisperse substrates from glucose to maltotriadecaose. HPTLC‐analysis of the product patterns in early states of CGTase catalyzed reactions revealed that the yield of the primary coupling product decreased with increasing DP. This was due to the effect, that disproportion was more rapid on higher oligomers. The intermolecular transfer of glucanosylgroups was also found to be size‐dependent, inasmuch as the relative CGTase transfer activity decreased gradually from maltohpxaosyl‐ to glucosylresidues. In an investigation of the enzymic degradation of maltodextrins maltononaose gave the highest yield of α‐CD.