Phosphoribosyl anthranilate isomerase

Priestle, J.P, et al. Three-dimensional structure of the bifunctional enzyme N-(5 -phosphoribosyl) anthranilate isomerase-indole-3-glycerol-phosphate synthase from Escheriehia eoli. Proc. Natl. Aead. 

Besides having a noncovalent association of subunits as in tryptophan synthase, some enzymes are double-headed, in that they contain two distinct activities in a single polypeptide chain. A good example of this is the indole 3-glycerol phosphate-synthase-phosphoribosyl anthranilate isomerase bifunc-tional enzyme from the tryptophan operon of E. coli. The crystal structure of the complex has been solved at 2.0 A resolution.39 The two enzymes have been separated by genetic manipulation.40 The activity of the two separate monomeric monofunctional constituents is the same as in the covalent complex so there is no catalytic advantage of having the proteins fused. 

BV monooxygenase Baeyer-Villiger monooxygenase CHMO cyclohexanone monooxygenase COMT catechol O-methyltransferase PDC pyruvate decarboxylase PRAI phosphoribosyl anthranilate isomerase. 

C N-( 5 -phosphoribosyl) anthranilate isomerase none Amadori rearrangement... 

Anthranilate synthase (I2, II2) iV-(5 -Phosphoribosyl)-anthranilate isomerase Tryptophan synthase ( 2 2) ... 

The high stability of the ( a)g barrel is emphasized in the statement that you can do almost anything and still get an a/jS-barrel [186], For example, a protein expected to contain a ( a)io barrel has been prepared, but it really forms a (j9a)g barrel and the other two )Sa-portions of the molecule form an additional dimer [187]. If the amino and carboxy ends of iV-(5 -phosphoribosyl)anthranilate isomerase are moved to different loops between j3-strands and a helices, there is not a large effect on enzymic activity [183], Since this ( )8 folding pattern is so common, its evolution has been the subject of much discussion, but no firm conclusions can yet be made [186], It is found that (jSa)g barrel enzymes can be recruited for other purposes , such as the use of enolase in the x-crystallin in the duck lens [186]. It has been noted that enolase and pyruvate kinase, both (jSa)g barrels, are consecutive enzymes in glycolysis [186, 188]. 

U. Hommel, M. Eberhard, and K. Kirsehner, Phosphoribosyl anthranilate isomerase eafalyzes a reversible Amadori reaction. Biochemistry, 34 (1995) 5429-5439. 

Phosphoribosyl anthranilate isomerase Indole glycerol phosphate synthase (E.C. 4.1.2.8)... 

Anthranilate phosphoribosyltransferase 2 phosphoribosyl anthranilate isomerase 3 indole-3-glycerol phosphate synthase 4 tryptophan synthase 25 Luckner, Metabolism... 

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