Rubber Research Institute of Cambodia, Khum de Chup, Kompong Cham, Cambodia.
Planta. 1969 Jun;88(2):144-53. doi: 10.1007/BF01391120.
Treatment of the bark ofHevea brasiliensis with 2,4-dichlorophenoxyacetic acid (2,4-D) or l-naphthylacetic acid (NAA) greatly increases sucrose level, invertase activity and sucrose utilization in the latex; the efficacy of 2,4-D is considerably greater than that of NAA. The greater sucrose utilization is the consequence of increased invertase activity. The changes occur as soon as the first tapping following bark treatment. It is suggested that the rise in both sucrose level and utilization in the latex serum mediate the effect of auxins on latex production. This is most likely related to a faciliation of latex outflow resulting from an increase in the osmotic and turgor pressure in the laticiferous tissue, as well as to enhanced regeneration of latex.The latex invertase has been found to be of a weakly alkaline type, with a sharp pH optimum at 7.15-7.20 in citrate-phosphate buffer. Its activity falls of rapidly on the acid side, being almost zero at pH 6.4. Since the natural pH of latex generally varies between pH 6.5 and 7.0, it is suggested that pH is an important factor in the regulation of invertase activity in the latex, and that the limiting nature of invertase-mediated sucrose hydrolysis in latex serum is caused by unfavourable conditions for invertase activity rather than by a scarcity of this enzyme.
用 2,4-二氯苯氧乙酸（2,4-D）或萘乙酸（NAA）处理巴西橡胶树的树皮会大大提高胶乳中的蔗糖水平、转化酶活性和蔗糖利用率；2,4-D 的效果比 NAA 好得多。蔗糖利用率的提高是由于转化酶活性的增加。在树皮处理后的第一次割胶时就会出现这种变化。因此，生长素对乳胶产量的影响是通过提高乳胶血清中的蔗糖水平和利用率来介导的。这很可能与乳管组织中渗透和膨压的增加导致乳胶流出的促进有关，以及与乳胶的再生增强有关。已发现乳胶中的转化酶为弱碱性，在柠檬酸-磷酸盐缓冲液中的 pH 最佳值为 7.15-7.20。其活性在酸性侧迅速下降，在 pH 6.4 时几乎为零。由于乳胶的天然 pH 值通常在 6.5 到 7.0 之间变化，因此，建议 pH 值是调节乳胶中转化酶活性的一个重要因素，并且是由于不利于转化酶活性而不是由于缺乏这种酶而导致乳胶血清中蔗糖水解受到限制。
