Separation And Purification Of S-adenosyl-l-methionine And Its Stable Salt Preparation Process

S-adenosyl-L -methionine (SAM, also known as Ado-Met, SAMe), an important product of intermediate metabolism, is widely found in various organisms. The influence of temperature and pH on SAM, the purification and preparation process of SAM with its stable salts SAM sulphate, SAM·p-toluenesulfonate sulphate and SAM·1, 4 -butanedisulphonate salt, the thermal stability of SAM sulphate and SAM ·p-toluenes -ulfonate sulphate were studied in this paper.The study on the stability of SAM indicated, under the condition of 4℃, the experiment had shown that from pH 3.0 to pH 7.0, k_d increased correspondingly from 1.810×10^-3 gL^-1h^-1 to 4.817×10^-3 gL^-1h^-1; under the condition of pH3.0, the degradation velocity constant k_d increased from 4.438×10^-2 gL^-1h^-1 to 7.11×10^-1 gL^-1h^-1 when the temperature increased from 50℃ to 70℃. It was obviously that the SAM degradation velocity was affected both by the temperature and the pH. So during the process of purification of SAM, it was necessary to keep operation under low temperature and pH to avoid the degradation of SAM.Compared with the traditional way of using picric acid or picrolonic: acid to precipitate SAM selectively, this method not only increased the recovery, but also diminished the operation risk and the environmental pollution. It was shown in the study that the optimal absorption condition of SAM in the JK110 weak cation exchange resin was: concentration of SAM solution: 4.98g/L; flow rate: 2BV/L; pH5.0. Using sulphuric acid to elute SAM and the suitable elution condition was found as follows: sulphuric acid concentration: 0.1mol/L, flow rate: 2BV/h. Flow rate had little influence on elution effectivity. The recovery of SAM reached 91.9%.The reversal phase precipitation method was involved in the preparation of SAM sulphate and SAM·p-toluenesulfonate sulphate which improved the crystallization yield and product purity. The yield of SAM sulphate reached 97.0% with the purity of 92%; the yield of SAM· p-toluenesulfonate sulphate reached 87.5%.It was found that the thermal stability of SAM· p-toluenesulfonate sulphate was greatly improved. Under the condition of 45℃, the active composition in SAM sulphate reduced by 61.0% while 18.4 in SAM· p-toluenesulfonate sulphate after 30 days.In the addition of surfactant EDTA of the reaction system the reaction time was shortened from 36 hours in the literature to about only 3 hours. The product yield was 99.39%. Besides, an analytic method based on the high performance capillaries electrophoresis (HPCE) was established. The precision, recovery and repeatability ofthe methods were evaluated. The results showed that the linear correlation coefficient for the method was 0.999, and recovery ratio was 96.5%.Coefficients of variation within and between days were 0.8% and 0.5%, respectively. The established analytic method was fast, accurate and repeatable, which had been successfully applied in the synthesis process of 1, 4-butanedisulphonic disodium salt.Using 1, 4-butanedisulphonic acid to elute SAM and get the optimal elution condition as follows: the concentration of 1, 4-butanedisulphonic acid: 0.2mol/L. By this condition the eluting peak centralized and the elution efficiency reached 96.17%. Flow rate had little influence on the efficiency. The previous obtained eluate passed through a column containing macroporous absorption resin to remove the excessive 1, 4- butanedisulphonic acid. The collected eluate went under spray drying to get the product.This paper aimed at developing and improving the SAM purification method, establishing an effective way to prepare SAM stable salts with lower cost and higher yield.