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Query: HUMANGGP:029284 (Histidine ammonia-lyase)
 12 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Histidine ammonia-lyase (histidase) was purified to homogeneity from vegetative mycelia of Streptomyces griseus. The enzyme was specific for L-histidine and showed no activity against the substrate analog, D-histidine. Histidinol phosphate was a potent competitive inhibitor. Histidase displayed saturation kinetics with no detectable sigmoidal response. Neither thiol reagents nor a variety of divalent cations had any effect on the activity of the purified enzyme. High concentrations of potassium cyanide inactivated histidase in the absence of its substrate or histidinol phosphate, suggesting that, as in other histidases, dehydroalanine plays an important role in catalysis. The N-terminal amino acid sequence of histidase was used to construct a mixed oligonucleotide probe to identify and clone the histidase structural gene, hutH, from genomic DNA of the wild-type strain of S. griseus. The cloned DNA restored the ability of a histidase structural gene mutant to grow on L-histidine as the sole nitrogen source. The deduced amino acid sequence of hutH shows significant relatedness with histidase from bacteria and a mammal as well as phenylalanine ammonia-lyase from plants and fungi.
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PMID:Purification of histidase from Streptomyces griseus and nucleotide sequence of the hutH structural gene. 153 7

Histidine ammonia-lyase (histidase; HutH) has been purified to homogeneity from Streptomyces griseus and the N-terminal amino acid (aa) sequence used to clone the histidase-encoding structural gene, hutH. The purified enzyme shows typical saturation kinetics and is inhibited competitively by D-histidine and histidinol phosphate. High concentrations of K.cyanide inactivate HutH unless the enzyme is protected by the substrate or histidinol phosphate. On the basis of the nucleotide sequence, the hutH structural gene would encode a protein of 53 kDa with an N terminus identical to that determined for the purified enzyme. Immediately upstream from hutH is a region that strongly resembles a class of Streptomyces promoters active during vegetative growth; however, there is no obvious ribosome-binding site adjacent to the hutH translation start codon. The deduced aa sequence of an upstream partial open reading frame shows no similarity with other proteins, including HutP of Bacillus subtilis and HutU of Pseudomonas putida. Promoter-probe analysis indicates that promoter activity maps within the DNA surrounding the hutH start codon. Pairwise comparisons of the primary structures of bacterial and mammalian histidases, together with the unique kinetic properties and gene organization, suggest that streptomycete histidase may represent a distinct family of histidases.
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PMID:Histidine ammonia-lyase from Streptomyces griseus. 161 36

Histidine ammonia-lyase (histidase) from Pseudomonas putida was irreversibly inactivated by L-cysteine at pH 10.5 in the presence of oxygen. Inactivation was accompanied by the formation of a new uv-absorbing species centered around 340 nm. L-[35S]cysteine labeling experiments revealed that 4 mol of L-cysteine was bound per mole of enzyme tetramer upon complete modification. However, the radiolabel was dissociated from the protein under denaturing conditions without loss of the 340-nm absorbance. Prior inactivation of histidase by cyanide, borohydride, or bisulfite precluded the formation of the 340-nm species in subsequent L-cysteine modification experiments. This suggests a common target site for modification of histidase by all of these reagents. Based on its strong absorbance at 340 nm an octapeptide was isolated from L-cysteine-inactivated histidase following trypsin and staphylococcal V8 protease digestion. Electrospray MS/MS revealed that this peptide (Gly138-SerValGlyAlaSerGlyAsp145) contained an unidentified modification of mass 184 Da located on Ser143. This peptide and the serine residue are conserved in all histidases and phenylalanine ammonia-lyases for which the amino acid sequence is available. Ser143 represents the binding site for an electrophilic cofactor required for histidase activity.
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PMID:Identification of Ser143 as the site of modification in the active site of histidine ammonia-lyase. 823 49

Histidine ammonia-lyase (HAL) from Pseudomonas putida PRS1 contains a catalytically important electrophilic center reported to be dehydroalanine. Little is known about the origin of this group or its linkage to the protein. To initiate structural studies on this enzyme, P. putida HAL was purified from an Escherichia coli high-expression clone in which the HAL gene (hutH) was under the control of the lambda PL promoter on a plasmid vector. In this clone from 6 to 10% of the soluble cell protein after heat induction was HAL and approximately 200 mg of 95% pure HAL could be obtained from 120 g wet weight of cells in a 40 to 60% yield. The overexpressed protein was identical to P. putida HAL in native molecular weight (220 kDa), subunit composition (four identical subunits of 53 kDa each), affinity for substrate (L-histidine Km of 5.3 mM at pH 9.0), and its sensitivity to inactivation by cyanide and bisulfite. The N-terminal amino acid sequence was in agreement with the DNA-predicted sequence, indicating proper translational initiation. These features make this enzyme an appropriate candidate for protein structure investigations regarding the nature of the electrophilic center and its association with the protein.
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PMID:Purification and characterization of Pseudomonas putida histidine ammonia-lyase expressed in Escherichia coli. 825 59