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)

A series of N-alkylmaleimides varying in chain length from N-ethyl up to and including N-heptyl, was shown to effectively inactivate Haemophilus influenzae D-lactate dehydrogenase at pH 7.0 and 25 degrees C in processes proposed to involve covalent modification of cysteine residues. The inactivation proceeded through an initial reversible binding of maleimides facilitated by nonpolar interactions with a hydrophobic region of the enzyme. Subsequent irreversible inactivation of the enzyme indicated the modification of a fast-reacting group leading to approx. 80% loss of enzyme activity followed by a second slower-reacting modification process. At saturating concentrations of maleimides, the second inactivation process exhibited a common pseudo-first-order rate constant of 0.6 min-1. The initial reversible binding of N-alkylmaleimides resulted in inhibition of the enzyme that was competitive with respect to NADH. Positive chain length effects were observed in the second-order rate constants for inactivation and in the 6-fold better binding of N-heptylmaleimide as compared to that for N-ethylmaleimide. It is suggested that the nonpolar interactions stabilizing the 1,4-dihydronicotinamide moiety of the reduced coenzyme also facilitate the initial binding of N-alkylmaleimides.
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PMID:Nonpolar interactions in the maleimide inactivation of Haemophilus influenzae D-lactate dehydrogenase. 237 5

A simple procedure for conjugating synthetic fragments of the capsular polysaccharide of Haemophilus influenzae type b, poly-3-beta-D-ribose-(1,1)-D-ribitol-5-phosphate (sPRP) to linear peptides is described. The procedure consists of (i) reacting the amino group of amino-heptyl sPRP with m-maleimidobenzoyl-N-hydroxysuccinimide (MBS) in phosphate buffer, pH 7.5; (ii) selectively coupling the MBS-modified sPRP to the sulfhydryl group of the cysteine residue of peptides containing functional T-helper cell epitope(s). The glycopeptide conjugates were purified by gel filtration chromatography, biochemically characterized, and elicited protective level of anti-PRP antibody responses in rabbits.
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PMID:Chemical synthesis of Haemophilus influenzae glycopeptide conjugates. 907 9