- Peptidyl cyclopropenones: Reversible inhibitors, irreversible inhibitors, or substrates of cysteine proteases?
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Peptidyl cyclopropenones were previously introduced as selective cysteine protease reversible inhibitors. In the present study we synthesized one such peptidyl cyclopropenone and investigated its interaction with papain, a prototype cysteine protease. A set of kinetics, biochemical, HPLC, MS, and 13C-NMR experiments revealed that the peptidyl cyclopropenone was an irreversible inhibitor of the enzyme, alkylating the catalytic cysteine. In parallel, this cyclopropenone also behaved as an alternative substrate of the enzyme, providing a product that was tentatively suggested to be either a spiroepoxy cyclopropanone or a gamma-lactone. Thus, a single family of compounds exhibits an unusual variety of activities, being reversible inhibitors, irreversible inhibitors and alternative substrates towards enzymes of the same family.
- Cohen, Meital,Bretler, Uriel,Albeck, Amnon
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p. 788 - 799
(2013/09/02)
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- Pyridines from azabicyclo[3.2.0]hept-2-en-4-ones through a proposed azacyclopentadienone
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Pyridines have been formed by heating azabicyclo[3.2.0]hept-2-en-4-ones in toluene. The generation of a 3-azacyclopentadienone intermediate via a [2 + 2]-cycloreversion is proposed as the key step. A Diels-Alder reaction of a styrene, extrusion of carbon monoxide, and loss of hydrogen then gives the pyridine. The process parallels the well-known synthesis of benzenes from cyclopentadienones. The azabicyclo[3.2.0]hept-2-en-4-ones were synthesized from the reaction between readily available cyclopropenones and 1-azetines, in which the cyclopropenones behave as all-carbon 1,3-dipolar equivalents.
- Hemming, Karl,Khan, Musharraf N.,Kondakal, Vishnu V. R.,Pitard, Arnaud,Qamar, M. Ilyas,Rice, Craig R.
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p. 126 - 129
(2012/02/16)
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