Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0348321 (Haemophilus)
 15,372 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Inoculation of Haemophilus equigenitalis into the uterus of 7 mares caused a disease clinically indistinguishable from contagious equine metritis. The duration of clinical signs varied from 4 to 11 days. The causative organism persisted for a relatively short time (2 to 10 weeks) in 5 mares, but in 2 others it established a carrier status and persisted until they were killed 6 and 10 months after infection. H. equigenitalis was recovered from the vestibule of the vagina and from a combined swab of the clitoral fossa and sinuses throughout the course of the infection. In some mares there were extended periods (2 weeks) when it could not be reisolated. All mares experienced a transitory serological response to infection. The complement fixation test was generally negative 12 weeks after infection whereas antibodies detected by the passive haemagglutination test and serum agglutination test were more persistent. In some animals the PHT and SAT titres increased during the breeding season following infection. The serological response did not appear to be related to the duration of infection.
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PMID:Experimental infection of mares with Haemophilus equigenitalis. 633 66

Capsular serotypes of 122 respiratory Haemophilus influenzae strains were identified utilizing antigenic examinations (Slide Agglutination Test [SAT] and counter immuno-electrophoresis [CIE]), and PCR method. Results of the two methods were compared to find disagreement. Clinical and bacteriological characteristics of encapsulated strains were analyzed. By utilizing PCR assay, 3 (2.5%) serotype b, 1 (0.8%) serotype f and 118 (96.7%) non-typeable strains were found among 122 tested strains. Discrepancy between the results of antigenic examinations and PCR assay was found in one strain. That strain gave positive results by antigenic tests with capsular type c antiserum but it was determined to be capsular type f by PCR. No serotype b- strain was detected. All the encapsulated strains displayed biotype I. All the serotype b strains produced beta-lactamase, but none of those was sulbactam/ampicillin and amoxicillin/clavulanic acid resistant. The serotype f strain was beta-lactamase non-producing ampicillin susceptible. The patients suffered from respiratory infections due to encapsulated strains displayed safe clinical manifestations and good clinical responses to antibiotic treatments using beta-lactams. In pre-vaccination era, PCR is considered to be a useful method for determination of serotypes of respiratory H. influenzae, which may contribute to reducing a possibility of clonal transmission of serotype b strains among children community, which is one of the potential risk factors for pediatric invasive infections.
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PMID:Serotypes of Haemophilus influenzae strains isolated from pediatric patients with respiratory tract infections. 1510 22

Serine acetyltransferase (SAT, EC 2.3.1.30) catalyzes the CoA-dependent acetylation of the side chain hydroxyl group of l-serine to form O-acetylserine, as the first step of a two-step biosynthetic pathway in bacteria and plants leading to the formation of l-cysteine. This reaction represents a key metabolic point of regulation for the cysteine biosynthetic pathway due to its feedback inhibition by cysteine. We have determined the X-ray crystal structure of Haemophilus influenzae SAT in complexes with CoA and its cysteine feedback inhibitor. The enzyme is a 175 kDa hexamer displaying the characteristic left-handed parallel beta-helix (LbetaH) structural domain of the hexapeptide acyltransferase superfamily of enzymes. Cysteine is bound in a crevice between adjacent LbetaH domains and underneath a loop excluded from the coiled LbetaH. The proximity of its thiol group to the thiol group of CoA derived from superimposed models of the cysteine and CoA complexes confirms that cysteine is bound at the active site. Analysis of the contacts of SAT with cysteine and CoA and the conformational differences that distinguish these complexes provides a structural basis for cysteine feedback inhibition, which invokes competition between cysteine and serine binding and a cysteine-induced conformational change of the C-terminal segment of the enzyme that excludes binding of the cofactor.
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PMID:Structure of serine acetyltransferase in complexes with CoA and its cysteine feedback inhibitor. 1514 85

The kinetic mechanism of serine acetyltransferase from Haemophilus influenzae was studied in both reaction directions. The enzyme catalyzes the conversion of acetyl CoA and L-serine to O-acetyl-L-serine (OAS) and coenzyme A (CoASH). In the direction of L-serine acetylation, an equilibrium ordered mechanism is assigned at pH 6.5. The initial velocity pattern in the absence of added inhibitors is best described by a series of lines converging on the ordinate when L-serine is varied at different fixed levels of acetyl CoA. The initial velocity pattern at pH 7.5 is also intersecting, but the lines are nearly parallel. Product inhibition by OAS is noncompetitive against acetyl CoA, while it is uncompetitive against L-serine. Product inhibition by L-serine in the reverse reaction direction is noncompetitive with respect to both OAS and CoASH. Glycine and S-methyl-L-cysteine (SMC) were used as dead-end analogs of L-serine and OAS, respectively. Glycine is competitive versus L-serine and uncompetitive versus acetyl CoA, while SMC is competitive against OAS and uncompetitive against CoASH. Desulfo-CoA was used as a dead-end analog of both acetyl CoA and CoASH, and is competitive versus both substrates in the direction of L-serine acetylation; while it is competitive against CoASH and noncompetitive against OAS in the direction of CoASH acetylation. All of the above kinetic parameters are consistent with those predicted for an ordered mechanism at pH 6.5 with the exception of the uncompetitive inhibition by OAS vs. serine. The latter inhibition pattern suggests combination of OAS with the central E:acetyl CoA:serine complex. Cysteine is known to regulate its own biosynthesis at the level of SAT. As a dead-end inhibitor, L-cysteine is competitive against both substrates in both reaction directions. These results are discussed in terms of the mechanism of regulation.
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PMID:Kinetic mechanism of the serine acetyltransferase from Haemophilus influenzae. 1531 14