نتایج جستجو برای: tryptophan synthase
تعداد نتایج: 99594 فیلتر نتایج به سال:
The pathway of aromatic amino acid biosynthesis was initiated by the enzyme DAHP synthase. In this branched biosynthetic pathway phenylalanine, tyrosine and tryptophan are produced. This enzyme was repressed and inhibited by three said end product of aromatic amino acids. The importance of this enzyme is microbial fermentation of aromatic amino acid production. The present study envisaged the i...
Previous studies have implicated indole-3glycerol phosphate as an intermediate in the biosynthesis of tryptophan in Escherichia coli (Yanofsky, 1956a, b) and Neurospora crassa (Yanofsky and Rachmeler, 1958; DeMoss, Imai, and Bonner, 1958; Suskind and Jordan, 1959). It has also been established that this compound is converted to tryptophan by the enzyme tryptophan synthetase in both organisms (D...
We report that l-threonine may substitute for l-serine in the β-substitution reaction of an engineered subunit of tryptophan synthase from Pyrococcus furiosus, yielding (2S,3S)-β-methyltryptophan (β-MeTrp) in a single step. The trace activity of the wild-type β-subunit on this substrate was enhanced more than 1000-fold by directed evolution. Structural and spectroscopic data indicate that this ...
We previously reported that laboratory reference strains of Chlamydia trachomatis differing in infection organotropism correlated with inactivating mutations in the pathogen's tryptophan synthase (trpBA) genes. Here, we have applied functional genomics to extend this work and find that the paradigm established for reference serovars also applies to clinical isolates - specifically, all ocular t...
Anthranilate synthase catalyzes the synthesis of anthranilate from chorismate and glutamine and is feedback-inhibited by tryptophan. The enzyme of the hyperthermophile Sulfolobus solfataricus has been crystallized in the absence of physiological ligands, and its three-dimensional structure has been determined at 2.5-A resolution with x-ray crystallography. It is a heterotetramer of anthranilate...
In Rhizobium meliloti, the genes involved in biosynthesis of the amino acid tryptophan are found at three separate chromosomal locations. Of the three gene clusters, trpE(G), trpDC, and trpFBA, only the trpE(G) gene is regulated by the end product of the pathway, tryptophan. We found that trpE(G) mRNA contains a leader transcript that terminates at a stem-loop structure in a putative transcript...
I N biennial white-blossomed sweetclover (Melilotus alba Desr.) , the B/b allelic pair controls .&glucosidase activity ( SCHAEFFER, HASKINS and GORZ 1960; HASKINS and GORZ 1965). Homogenates of BB and Bb plants are high and iatermediate, respectively, in /3-glucosidase activity. No activity has been detected in homogenates of bb plants. The precise effect of the alleles B and b on the enzyme ha...
Previous studies (2, 4) have led to the conclusion that Reaction 3 is probably the physiologically essential reaction in the biosynthesis of tryptophan in E. coli. Studies of the relationship between gene structure and protein structure which are presently being carried out with the A component of this system (5-8) have necessitated investigations of the properties, composition and primary stru...
Enzymes in heteromeric, allosterically regulated complexes catalyze a rich array of chemical reactions. Separating the subunits of such complexes, however, often severely attenuates their catalytic activities, because they can no longer be activated by their protein partners. We used directed evolution to explore allosteric regulation as a source of latent catalytic potential using the β-subuni...
BACKGROUND AND OBJECTIVES The essential amino acid L-tryptophan can be produced by a condensation reaction between indole and L-serine, catalyzed by B. subtilis with tryptophan synthase activity. Application of the tryptophan is widespread in the biotechnology domain and is sometimes added to feed products as a food fortifier. MATERIALS AND METHODS The optimum concentration of the Iranian can...
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