Ray P M
Department of Biological Sciences, Stanford University, Stanford, California 94305.
Plant Physiol. 1973 Apr;51(4):609-14. doi: 10.1104/pp.51.4.609.
The 2- to 4-fold rise in particle-bound beta-glucan synthetase (uridine diphosphate-glucose: beta-1, 4-glucan glucosyltransferase) activity that can be induced by indoleacetic acid in pea stem tissue is not prevented by concentrations of actinomycin D or cycloheximide that inhibit growth and macromolecule synthesis. The rise is concluded to be a hormonally induced activation of previously existing, reversibly deactivated enzyme. The activation is not a direct allosteric effect of indoleacetic acid or sugars. It is blocked by inhibitors of energy metabolism, by 2-deoxyglucose, and by high osmolarity, but not by Ca(2+) at concentrations that inhibit auxin-induced elongation and prevent promotion of sugar uptake by indoleacetic acid, and not by alpha, alpha'-dipyridyl at concentrations that inhibit formation of hydroxyproline. Regulation of the system could be due either to an ATP-dependent activating reaction affecting this enzyme, or to changes in levels of a primer or a lipid cofactor.
吲哚乙酸可诱导豌豆茎组织中与颗粒结合的β-葡聚糖合成酶（尿苷二磷酸葡萄糖：β-1,4-葡聚糖葡糖基转移酶）活性升高2至4倍，而抑制生长和大分子合成的放线菌素D或环己酰亚胺浓度并不能阻止这种升高。由此得出结论，这种升高是激素诱导的对先前存在的、可逆失活的酶的激活。这种激活不是吲哚乙酸或糖类的直接别构效应。它被能量代谢抑制剂、2-脱氧葡萄糖和高渗透压阻断，但不被抑制生长素诱导伸长和阻止吲哚乙酸促进糖类摄取的浓度的Ca(2+)阻断，也不被抑制羟脯氨酸形成的浓度的α,α'-联吡啶阻断。该系统的调节可能是由于影响该酶的ATP依赖性激活反应，或者是由于引物或脂质辅因子水平的变化。
