Maleate isomerase

MALEATE ISOMERASE MALONYL-C0A.ACP TRANSACYLASE MALYL-CoA LYASE... 

Aspartate from Maleic Acid Using Maleate Isomerase... 

Since maleic acid is a cheaper starting material than fumaric acid, the process that is probably the most economical makes use of both a maleate isomerase (E. C. 5.2.1.1) and aspartase (E.C. 4.3.1.1), Scheme 12.6-1. Mitsubishi has succeeded in... 

L-Aspartate is produced by a one-step enzymatic method from fumarate and ammonia and by a two-step method from maleate via fumarate. The conversion of fumarate to L-aspartate is catalyzed by aspartase and maleate to fumarate by maleate isomerase ... 

A new system for the enzymatic production of L-aspartate was proposed and started in the 1990s. In this system, resting intact cells of coryneform bacteria were used without immobilization and with an ultrafiltration membrane. This bacterial strain possesses high maleate isomerase and aspartase activities thorough transformation of their genes. The plasmids introduced were stabilized and the cells were reused many times without any loss of activity and lysis [17]. 

Glu racemase Asp racemase Hydantoin racemase Maleate isomerase AMDase... 

An interesting use is made of addition to a double bond by glutathione-dependent cis-tmns isomerases.76 One of them converts maleate to fumarate with a turnover number of 300 s"1. Similar enzymes, which participate in bacterial breakdown of aromatic compounds (Fig. 25-7), isomerize maleylacetoacetate and maleylpyruvate to the corresponding fumaryl derivatives (Eq. 13-20). The - SH group of bound glutathione is thought to add to the double bond. Rotation can then occur in the enolic intermediate. Thiocyanate ion catalyzes the isomerization of maleic acid nonenzy-matically, presumably by a similar mechanism. 

We describe here the enzymological characteristics and application of isomerases, especially D-xylose (glucose) isomerase, phosphoglucose isomerase, triose phosphate isomerase, L-rhamnose isomerase, L-fucose isomerase, maleate cis-trans isomerase, and unsaturated fatty acid cis-trans isomerase. N-Acetyl-D-glucosamine 2-epimerase is not an isomerase, but for convenience we will also describe the characteristics and use of the enzyme because this section deals with sugar-metabolizing enzymes. 

Maleate cis-trans isomerase catalyzes the conversion of maleate into fumarate. This enzyme is applicable to the production of L-aspartate by coupling with the aspartase reaction as shown in Fig. 17-34[262, 263i. First, maleate is isomerized to fumarate by... 

Figure 17-34. Synthesis of i-aspartate using maleate cis-trans isomerase and aspartase.

K. Hatakeyama, Y. Asai, Y. Uchida, M. Kobayashi, M. Terasawa and H. Yukawa, "Gene cloning and characterization of maleate cis-trans isomerase from Alcaligenes faecalis", Biochemical and Biophysical Research Communications 239, 74—79 (1997). 

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