Modification of human placental alkaline phosphatase by periodate-oxidized 1,N6-ethenoadenosine monophosphate

Oxidation of 1,N6-ethenoadenosine monophosphate (epsilon AMP) with periodate cleaved the cis-diol of the ribose ring and resulted in the formation of a dialdehyde derivative (epsilon AMP-dial). At room temperature epsilon AMP-dial was unstable and underwent beta-elimination to give 4',5'-a...

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Bibliographic Details
Published in:Biochemical journal 1990-12, Vol.272 (3), p.683-690
Main Authors: Chang, G G, Shiao, M S, Lee, K R, Wu, J J
Format: Article
Language:English
Subjects:
Adenosine Monophosphate - analogs & derivatives
Adenosine Monophosphate - pharmacology
Alkaline Phosphatase - isolation & purification
Alkaline Phosphatase - metabolism
Analytical, structural and metabolic biochemistry
Biological and medical sciences
Enzymes and enzyme inhibitors
Female
Fundamental and applied biological sciences. Psychology
Humans
Hydrolases
Kinetics
Mathematics
Models, Theoretical
Oxidation-Reduction
Periodic Acid
Placenta - enzymology
Pregnancy
Protein Binding
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Summary:Oxidation of 1,N6-ethenoadenosine monophosphate (epsilon AMP) with periodate cleaved the cis-diol of the ribose ring and resulted in the formation of a dialdehyde derivative (epsilon AMP-dial). At room temperature epsilon AMP-dial was unstable and underwent beta-elimination to give 4',5'-anhydro-1,N6-ethenoadenosine dialdehyde acetal (A epsilon Ado-dial). These nucleotide analogues were found to inactivate human placental alkaline phosphatase in a time- and concentration-dependent manner. epsilon AMP-dial was shown to be an affinity label for the enzyme on the basis of the following criteria. (a) Kinetics of the enzyme activity loss over a wide range of epsilon AMP-dial concentration showed a saturating phenomenon. Removal of the phosphate group made the reagent (A epsilon Ado-dial) become a general chemical modifying reagent. (b) The artificial substrate p-nitrophenyl phosphate gave substantial protection of the enzyme against inactivation. (c) epsilon AMP-dial was a substrate and a partial mixed-type inhibitor for the enzyme. Results of the inhibition and protection studies indicated that the reagent and substrate could combine with the enzyme simultaneously. Besides the phosphate-binding domain, an induced hydrophobic region is proposed for the substrate-binding site for human placental alkaline phosphatase.
ISSN:0264-6021
1470-8728
DOI:10.1042/bj2720683