Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: DrugBank:EXPT00572 (Asn)
 11,732 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The Avi-3 antigen, which is found only in Mycobacterium avium culture sonic extracts, is species specific and results in strong skin test activity in guinea pigs sensitized with heat-killed M. avium. Its gene was cloned by using a previously developed single-probe method and was sequenced. The gene encoded a 194-amino-acid polypeptide with a molecular weight of 21,500. A recombinant Avi-3 antigen expressed in Escherichia coli reacted with monoclonal and polyclonal antibodies raised against the native Avi-3 antigen. To identify epitopes on this protein for immunodiagnostic purposes, various parts of the Avi-3 antigen were expressed as beta-galactosidase fusion proteins, using pUR and pURS expression vectors. The clones screened by both antibody reactivity and T-cell proliferative activity defined fragments with coexisting B- and T-cell epitopes. A B-cell epitope (Asn-176 to Ala-186) and two T-cell epitopes (Glu-75 to Ile-86 and Arg-155 to Leu-164) were thus defined. The synthetic polymerized peptides of the T-cell epitopes were proven to elicit a delayed cutaneous hypersensitivity reaction in guinea pigs. This mapping method would be useful in the development of a subunit vaccine consisting of an immunodominant B-cell epitope linked to a T-cell epitope in the vicinity.
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PMID:Cloning and expression of the gene for the Avi-3 antigen of Mycobacterium avium and mapping of its epitopes. 137 65

We report characterisation of three copies of a novel repeat sequence isolated from a Mycobacterium bovis genomic library. The repeat occurs within open reading frames, potentially encoding a conserved tandem array of a pentapeptide sequence with the consensus X-Gly-Asn-X-Gly. The tandem array is present up to five times in M. bovis and it is proposed that they may occur in a family of genes expressing functionally related proteins. We postulate that these proteins may play a role in binding of M. bovis to host cell receptors.
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PMID:Characterisation of a novel repetitive DNA sequence from Mycobacterium bovis. 139 35

We synthesized an octapeptide, H-Asp-Gly-Gly-Ser-Glu-Ser-Glu-Gly-OH, and a hexadecapeptide, H-Asp-Gly-Gly-Ser-Glu-Ser-Glu-Gly-Lys-Asn-Gly-Ser-Gln-Met-Arg-Leu-OH, which corresponded to amino acids 61 to 68 and 61 to 76, respectively, of the amino acid sequence of a crystalline protein reported to be tuberculin active. Authenticity and purity of the synthesized peptides were confirmed by high-pressure liquid chromatography, amino acid analysis, mass spectrometry, and protein sequencer analysis. Tuberculin activity of the synthesized peptides was examined in guinea pigs sensitized with Mycobacterium tuberculosis or Mycobacterium bovis BCG and in tuberculin-positive healthy humans. Neither the octa- nor the hexadecapeptide was as active as tuberculin skin-test antigen.
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PMID:Lack of tuberculin activity of synthetic peptides. 406 24

l-Asparagine controls the utilization of other amino acids by Mycobacterium tuberculosis (H37Ra) in aerated, liquid synthetic media. In a mixture containing asparagine and either l-alanine or l-glutamic acid, amino acid utilization is diphasic, with asparagine being utilized first. Short-term growth rates and cell yields are diminished and mimic those seen with asparagine alone. Catabolite repression is the probable regulatory mechanism responsible for this effect of asparagine. In contrast, in the presence of aspartic acid, asparagine stimulates growth and increases utilization of aspartic acid.
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PMID:Effect of L-asparagine on growth of Mycobacterium tuberculosis and on utilization of other amino acids. 420 93

The heptapeptide Asn-Gly-Ser-Gln-Met-Arg-Leu, part of a tuberculin-active intracellular mycobacterial protein and described in the literature as having residual tuberculin activity, has been synthesized. Biological assays of the synthetic peptide showed it to be recognized as an antigen of mycobacterial origin by its ability to elicit an early allergic reaction in Mycobacterium bovis BCG-infected mice. The synthetic peptide was shown to be devoid of any tuberculin activity in BCG-infected mice and in skin tests on Mycobacterium tuberculosis-sensitized guinea pigs. Purified protein derivative, complex mixture of proteins of unknown composition which is excreted into the culture medium by M. tuberculosis and is in wide use as a tuberculin-active preparation, was shown to weakly cross-react in radioimmunoassays with the synthetic heptapeptide when 125I-labeled heptapeptide and an anti-heptapeptide antiserum were used.
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PMID:Synthesis and biological assays of a peptide from a tuberculin-active protein. 678 33

The octapeptide Asp-Gly-Gly-Ser-Glu-Ser-Glu-Gly and the hexadecapeptide Asp-Gly-Gly-Ser-Glu-Ser-Glu-Gly-Lys-Asn-Gly-Ser-Gln-Met-Arg-Leu, part of a tuberculin-active intracellular mycobacterial protein, were synthesized. The synthetic peptides were shown to possess tuberculin activity by their ability to elicit a delayed-type allergic reaction in skin tests on Mycobacterium tuberculosis-sensitized guinea pigs. Purified protein derivative, the complex mixture of proteins of unknown composition which are excreted into the culture medium by M. tuberculosis and which is in wide use as a tuberculin-active preparation, was shown to cross-react weakly in the radioimmunoassays with the synthetic octapeptide when the 125I-labeled octapeptide and an anti-octapeptide antiserum were used.
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PMID:Synthesis and biological assays of peptides from a tuberculin-active protein. 685 17

To examine the mechanism of resistance to fluoroquinolones in Mycobacterium tuberculosis, we selected spontaneous fluoroquinolone-resistant mutants from a susceptible strain, H37Rv, and studied the susceptibilities of these mutants and two fluoroquinolone-resistant clinical isolates (A-382, A-564) to various fluoroquinolones and to isoniazid and rifampin. Furthermore, since mutations within the quinolone resistance-determining region of the structural gene encoding the A subunit of DNA gyrase are the most common mechanism of acquired resistance, we amplified this region by PCR and compared the nucleotide sequences of the fluoroquinolone-resistant strains with that of the susceptible strain. Fluoroquinolone-resistant mutants of H37Rv appeared at frequencies of 2 x 10(-6) to 1 x 10(-8). For three mutants selected on ciprofloxacin, ofloxacin, and sparfloxacin, respectively, and the two clinical isolates, MICs of ciprofloxacin and ofloxacin were as high as 16 micrograms/ml, and those of sparfloxacin were 4 to 8 micrograms/ml. They displayed cross-resistance to all fluoroquinolones tested but not to isoniazid or rifampin. Sparfloxacin and FQ-A (PD 127391-0002) were the most potent fluoroquinolones. All of the fluoroquinolone-resistant strains (MICs, > or = 4 micrograms/ml) had mutations in the quinolone resistance-determining region which led to substitution of the Asp residue at position 87 (Asp-87) by Asn or Ala or the substitution of Ala-83 by Val in the A subunit of DNA gyrase. Similar mutations have been noted in other bacterial species and recently in mycobacteria. The broad resistance to fluoroquinolones that arose readily by point mutation in the laboratory and apparently during inadequate therapy, as was the case in the clinical isolates, may ultimately lead to to serious restriction of the use of these drugs in the treatment of tuberculosis.
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PMID:Characterization of fluoroquinolone-resistant mutant strains of Mycobacterium tuberculosis selected in the laboratory and isolated from patients. 748 4

An internal fragment of the Corynebacterium glutamicum recA gene was amplified by the polymerase chain reaction (PCR) using degenerate primers corresponding to two short sequences that are well conserved in procaryotic RecA proteins. The deduced amino acid sequence of the amplified fragment shared significant homology with RecA sequences from other bacteria including the "invariant" and functionally conserved amino acids Leu-126, Asp-144, Gly-157, Arg-169 and Asn-193. Highest identity (91%) was shared with the gram-positive Mycobacterium tuberculosis RecA sequence. The amplified fragment was cloned into a conditional suicide vector, pBGS, and used to generate recA deficient strains of C. glutamicum and Brevibacterium lactofermentum by insertional inactivation. These strains exhibited classical RecA phenotypes including reduced recombinational activity and increased sensitivity to DNA-damaging agents such as UV irradiation, mitomycin C and methyl-methanesulphonate.
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PMID:Construction and characterization of recA mutant strains of Corynebacterium glutamicum and Brevibacterium lactofermentum. 776 33

An integrated map of the genome of the tubercle bacillus, Mycobacterium tuberculosis, was constructed by using a twin-pronged approach. Pulsed-field gel electrophoretic analysis enabled cleavage sites for Asn I and Dra I to be positioned on the 4.4-Mb circular chromosome, while, in parallel, clones from two cosmid libraries were ordered into contigs by means of fingerprinting and hybridization mapping. The resultant contig map was readily correlated with the physical map of the genome via the landmarked restriction sites. Over 165 genes and markers were localized on the integrated map, thus enabling comparisons with the leprosy bacillus, Mycobacterium leprae, to be undertaken. Mycobacterial genomes appear to have evolved as mosaic structures since extended segments with conserved gene order and organization are interspersed with different flanking regions. Repetitive sequences and insertion elements are highly abundant in M. tuberculosis, but the distribution of IS6110 is apparently nonrandom.
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PMID:An integrated map of the genome of the tubercle bacillus, Mycobacterium tuberculosis H37Rv, and comparison with Mycobacterium leprae. 861 Jan 81

A 33-kDa protein (TB33) was isolated from a delipidated cell sonicate (CS) of Mycobacterium tuberculosis H37Rv (grown in Middlebrook 7H9 broth supplemented with glucose) using immobilized metal affinity chromatography (IMAC) on a nickel-nitrilotriacetic acid (Ni-NTA) column. TB33 could not be isolated from the culture filtrate (CF) of M. tuberculosis H37Rv using Ni-NTA. TB33 was recognized by monoclonal antibodies (mAb) known to react with proteins of M. tuberculosis with a molecular mass of 33/34 kDa; namely, mAb F126-5, F67-1 and F126-2. The N-terminal amino acid sequence of TB33 was found to be Xaa-Xaa-Thr-Pro-Ala-Asp-Val-Ser/Cys-Asn-Val-Ala-Ile and thus, shows identity with the N-terminal of antigen 84 of M. tuberculosis except for two mismatches. Antibodies to TB33 could be raised in mice by administering four injections of TB33 (40 micrograms total protein). Sera from tuberculosis patients reacted with TB33, while those from normal healthy individuals did not.
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PMID:Isolation of a 33-kDa protein antigen from delipidified Mycobacterium tuberculosis H37Rv. 900 20


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