Method for producing L-sodium malate through direct enzymatic conversion

Abstract

The invention discloses a method for producing L-sodium malate through direct enzymatic conversion. The method comprises the following steps: with fumaric acid and calcium salt as the raw materials, L-calcium malate is produced under the catalysis of fumarate hydratase, then after neutralizing of sodium carbonate, L-sodium malate is prepared. According to the method, by selectively cloning and expressing the coding gene segments of the fumarate hydratase catalyzing the forward reaction, the balance of the reaction deviates towards the direction of synthesis of L-malate, meanwhile, a calcium type substrate is adopted for carrying out catalyzing, thus the problem of the product quality caused by substrate residue is solved, moreover, calcium carbonate generated as the by-product is recycled,so that no discharge of by-products exists during the whole production process, the economical conversion of atoms is realized, and thus the method has the obvious industrial application value and environmental benefit.

Description

technical field [0001] The invention relates to an enzymatic conversion production method of L-sodium malate, belonging to the field of biocatalytic preparation of organic acids and salts thereof. Background technique [0002] L-sodium malate is an optical isomer of DL-sodium malate. Compared with DL-sodium malate, L-sodium malate can directly enter the tricarboxylic acid cycle to participate in the metabolism of the human body, and has important physiological activities Features. In DL-sodium malate, the D-sodium malate contained in it is not physiologically active and can only be utilized by the body after the action of racemase in the liver and oxidoreductase in the kidney. In view of this, DL-apple Sodium malate has been banned from being used in food for the elderly, patients with liver and kidney dysfunction, and infants and young children, so as to avoid the residue of D-sodium malate in the human body and thereby reduce the metabolic burden of the human body. There...

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Problems solved by technology

[0003] However, compared with the production cost of DL-sodium malate, the current commercial production technology of L-sodium malate is to prepare L-sodium malate by neutralizing L-malic acid and sodium carbonate. There are following disadvantages: (1) generate a large amount of calcium sulfate as by-product in this process, consume a large amount of sulfuric acid during acidolysis, and the consumption of calcium carbonate is also higher; (2) adopt L-malic acid to carry out And reaction when preparing L-sodium malate, because the price of L-malic acid as raw material is higher, therefore cause the production cost of L-sodium malate higher, thereby restricted the extensive application of L-sodium malate; ( 3) When the above process covers the production steps of L-malic acid, since this step involves concentration, crystallization, drying and other links, the overall energy consumption is relatively high

Due to the above treatment, the cost of further producing L-sodium malate through the neutralization reaction of L-malic acid is higher

[0005] In addition, it is mentioned in some prior art that the substrate fumaric acid is made into sodium fumarate and sodium malate can be generated through the hydration of fumarase, but since the reaction is reversible, the average conversion of sodium fumarate The rate is low (≤70%), and the concentration of target product (that is, L-sodium malate) is low, has caused the content of sodium fumarate in the final product to be too high, has increased follow-up separation cost, and to L-apple The quality of sodium malate has a greater adverse effect (and high-quality sodium L-malate is what the food industry needs)

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