Studies on Cellulose Synthesis by a Cell-free Oat Coleoptile Enzyme System: Inactivation by Airborne Oxidants

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Abstract
Particulate cell wall polysaccharide synthetase from oat coleoptiles could use either guanosine diphosphate glucose or uridine diphosphate glucose; the latter was a much more effective glucose donor. The neutral polymer derived from uridine diphosphate glucose utilization yielded, after cellulase digestion, mostly cellobiose and to a lesser extent a substance tentatively identified as a mixed-linkage β1,4 = β1,3-trisaccharide; only cellobiose was found after guanosine diphosphate glucose utilization. The uridine diphosphate glucose utilizing system was inactivated by peroxyacetyl nitrate treatment of intact tissue and to a lesser extent by ozone treatment suggesting that this system is a possible site of interference with cellulose and non-cellulosic glucan biosynthesis in vivo. Direct treatment of the enzyme in vitro by peroxyacetyl nitrate, iodoacetamide or p-chloromercuribenzoate also inactivated the enzyme, indicating that the mechanism of inactivation possibly involves reaction with sulfhydryl groups.
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