Inactivation by Airborne Oxidants'

Sunmmiary. Particuilate cell wall polysaccharide synthetase from oat coleoptiles could use either guanosine diphosphate glucose or turidine diphosphate glucose; the latter was a much more effective glucose donor. The neutral polymer derived from uridine diphosphate glu-cose utilization yielded, after cellulase digestion, mostly cellobiose and to a lesser extent a suibstance tentatively identified as a mixed-linkage ,l1,4 = 81,3-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 interfereince with cellulose and non-cellulosic gltucani 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.