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Precision synthesis of reducing-end thiol-modified cellulose enabled by enzyme selection
Ist Teil von
Polymer journal, 2022-04, Vol.54 (4), p.551-560
Ort / Verlag
Tokyo: Nature Publishing Group
Erscheinungsjahr
2022
Quelle
Alma/SFX Local Collection
Beschreibungen/Notizen
Abstract
Enzyme-catalyzed iterative
β
-1,4-glycosylation of
β
-glycosides is promising for bottom-up polymerization of reducing-end-modified cello-oligosaccharide chains. Self-assembly of the chains from solution yields crystalline nanocellulose materials with properties that are tunable by the glycoside group used. Cellulose chains with a reducing-end thiol group are of interest to install a controllable pattern of site-selective modifications into the nanocellulose material. Selection of the polymerizing enzyme (cellodextrin phosphorylase; CdP) was pursued here to enhance the synthetic precision of
β
-1-thio-glucose conversion to generate pure “1-thio-cellulose” (≥95%) unencumbered by plain (unlabeled) cellulose resulting from enzymatic side reactions. The CdP from
Clostridium stercorarium
(
Cs
CdP) was 21 times more active on
β
-1-thio-glucose (0.17 U/mg; 45 °C) than the CdP from
Clostridium cellulosi
(
Cc
CdP), and it lacked hydrolase activity, which is substantial in
Cc
CdP, against the α-
d
-glucose 1-phosphate donor substrate. The combination of these enzyme properties indicated that
Cs
CdP is a practical catalyst for 1-thio-cellulose synthesis directly from
β
-1-thio-glucose (8 h; 25 mol% yield) that does not require a second enzyme (cellobiose phosphorylase), which was essential when using the less selective
Cc
CdP. The 1-thio-cellulose chains had an average degree of polymerization of ∼10 and were assembled into highly crystalline cellulose II crystallinity material.