The phosphatides of the latex of Hevea brasiliensis. 1. Biochemical changes

Abstract

A method is descr. for the detn. of phosphatide P in the latex of H. brasilienis. Different latices gave values, immediately after tapping, varying from about 0.015 to 0.022%. In some cases this fell, after 8-hr, storage, by as much as 20% but in other cases there was no decrease. The phosphatide contains virtually all the choline present in fresh latex and possesses a choline N/ P ratio of about 0.68-0.77. The presence has, however, been demonstrated of an enzyme which is capable of causing the liberation of choline from latex phosphatide without any other apparent degradation. The liberation has been shown to occur after coagulation of the latex by the addition of alcohol below 40[degree], by the addition of formic acid, or by freezing; it does not occur in untreated latex. The total serum obtained by high speed (21,000 rev ./min.) centrifuging of latex contains the choline-liberating enzyme free from most of the latex phosphatide. This serum is highly active in liberating choline from egg lecithin in aqueous suspension or in alcoholic solution. In the former case an opt. temp, of about 30[degree] and an optimum pH of about 6.0 were observed. The degradation of latex phosphatide by this enzyme is accompanied by (i) the total lipid becoming more liquid; (ii) an increase in the solubility of the phosphatide in acetone; and (iii) the formation of metal phosphatidates, as evidenced by an increase in the ash phosphorus/total phosphorus ratio of the lipid. The enzyme is progressively inactivated in the period between tapping and spontaneous coagulation of the latex, probably owing to bacterial action.