Anthranilate synthetase

CPSase of arginine biosynthesis anthranilate synthetase component II p-aminobenzoaie synthetase GMP and CTP synthetases ... 

Similarly, enzymes can be allosterically regulated by association with other molecules. Often the first enzyme in a metabolic pathway is feedback-inhibited by the product of that pathway. For example, anthranilate synthetase, the first enzyme in the biosynthesis of tryptophan, is inhibited by tryptophan, but not by other amino acids. 

M. (1972) Regulation of aromatic amino acid biosynthesis in Bre-vibacterium Jlavum. 1. Regulation of anthranilate synthetase. J. Biochem.,... 

Figure 5.41 Early steps of the proposed indole acetic acid biosynthesis pathways for Ara-bidopsis. CHO, chorismate ANA, anthranilate PANA, 5-phosphoribosylanthranilate CADP, l-(o-carboxyphenylamino)-l-deoxyribulose-5-phosphate IGP, indole-3-glycerol phosphate TRP, tryptophan. Enzymes ASA, anthranilate synthetase, suhunit a ASB, anthranilate synthetase, suhunit P PAT, phosphorihosylanthranUate transferase PAI, phosphoiibosylanthrani-late isomerase IGS, indole-3-glycerol-phosphate synthase TSA, tryptophan synthase, subunit a and TSB, tryptophan synthase, suhunit p.

RNA-polymerase has left the operater-promotor site, and has started to transcribe the leader region as It proceeds In the direction of the first structurai gene of the operon (component I of anthranilate synthetase). The start codon for the ieader peptide has appeared, a ribosome has become attached, and transiation has started. 

S units. The separated 7.4 S fragment retains full activity for InGP synthetase and PRA isomerase. The 4.4 S fragment is inactive, but in the presence of dithiothreitol some anthranilate synthetase activity is restored. On the assumption that all the subunits are 40,000 MW, the following scheme has been proposed [65] to explain the data ... 

Fig. 1. The tryptophan biosynthetic pathway. Abbreviations AS, anthranilate synthetase PRPP, 5-phosphoribosyI-l-pyrophosphate PRT, phosphoribosyi transferase PRAI, phosphoribosyi anthranilate isomerase InGPS, indoleglycerol phosphate synthetase TS, tryptophan synthetase TS-a, tryptophan synthetase a-chain subunit TS- z, tryptophan synthetase -chain dimer subunit.

End-product inhibition of AS activity by tryptophan appears to be a rather common control mechanism among microorganisms. Nester and Jensen [71] described tryptophan inhibition of B. subtilis AS activity as the first step in sequential feedback control. Excess tryptophan would result in inhibition of the conversion of chorismate to anthrani-late. The consequent accumulation of chorismic acid would then serve as a feedback inhibitor of the DAMPS, the first enzyme in the pathway leading to chorismate synthesis. Bacillus alvei has an anthranilate synthetase which is extremely sensitive to inhibition by tryptophan [98]. In contrast to the mode of AS feedback inhibition in E. coli and S. typhimurium, the B. alvei AS is inhibited by tryptophan noncom-petitively with respect to chorismate and uncompetitively with respect to glutamine. It is the only Bacillus species, among 21 studied, which did not exhibit a sequential feedback control pattern [79]. 

The authors speculate about the incorporation of the reverse prenyl unit in this and related molecules such as echinulin, lanosulin, oxaline, austamide, and the brevianamides and infer the rearrangement of the N-prenyl to the reverse 2-prenyl structure as shown in Scheme 22. These workers investigated the involvement of the 2-position of the indole by deuterium labeling using an auxotrophic mutant strain of Penicillium roqueforti that was apparently deficient in anthranilate synthetase. 

LEE, H.G. FLOSS. 1984. Steric course of the 5-enolpyruvylshikimate-3-phosphate synthetase and anthranilate synthetase reactions. J. Am. Chem. 

Anilines, A -substituted, 95 Antamanide, 84 Anthranilate synthetase, 420 Antibiotics, 633-636, see also specific substances... 

Anthranilate synthetase the enzyme which catalyses the formation of anthranilate (34) from chorismate (14) and L-glutamine (Figure 1.14) has been isolated and characterised from a number of microorganisms. Two main types have been identified in bacteria. Type I has been obtained uncontaminated with other enzymes of the... 

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