Treatment of fragment A chain of diphtheria toxin (DT-A) with diethylpyrocarbonate modifies His-21, the single histidine residue present in the chain, without alteration of other residues. Parallel to histidine modification, NAD+ binding and the NAD-glycohydrolase and ADP-ribosyltransferase activities of DT-A are lost. Both NAD+ and adenosine are very effective in protecting DT-A from histidine modification and in preserving its biological properties, while adenine is ineffective. Reversal of histidine modification with hydroxylamine restores both NAD+ binding and enzymatic activities of the toxin. The possible role of His-21 in the activity of diphtheria toxin is discussed in relation to the available three-dimensional structure of the related toxin produced by Pseudomonas aeruginosa.

Histidine 21 is at the NAD+ binding site of diphtheria toxin

PAPINI, EMANUELE;SANDONA', DORIANNA;MONTECUCCO, CESARE
1989

Abstract

Treatment of fragment A chain of diphtheria toxin (DT-A) with diethylpyrocarbonate modifies His-21, the single histidine residue present in the chain, without alteration of other residues. Parallel to histidine modification, NAD+ binding and the NAD-glycohydrolase and ADP-ribosyltransferase activities of DT-A are lost. Both NAD+ and adenosine are very effective in protecting DT-A from histidine modification and in preserving its biological properties, while adenine is ineffective. Reversal of histidine modification with hydroxylamine restores both NAD+ binding and enzymatic activities of the toxin. The possible role of His-21 in the activity of diphtheria toxin is discussed in relation to the available three-dimensional structure of the related toxin produced by Pseudomonas aeruginosa.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11577/2485213
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