TAILIEUCHUNG - Báo cáo khoa học: 1,5-Diamino-2-pentyne is both a substrate and inactivator of plant copper amine oxidases

1,5-Diamino-2-pentyne (DAPY) was found to be a weak substrateof grasspea (Lathyrus sativus,GPAO) andsainfoin (Onobrychis viciifolia, OVAO) amine oxidases. Prolonged incubations, however, resulted in irreversible inhibition of both enzymes. For GPAOandOVAO, rates of inactivation of – min )1 were determined, the apparentKI values (half-maximal inactivation) were of the order of 10 )5 M. DAPY was found to be amechanism-based inhibitor of the enzymes because the substrate cadaverine significantly pre-vented irreversible inhibition. . | Eur. J. Biochem. 271 4696-4708 2004 FEBS 2004 doi 1 5-Diamino-2-pentyne is both a substrate and inactivator of plant copper amine oxidases Zbvnek Lamnlot1. Marek Sebela1 Michal Malon2 Rents Lenobel2. Karel Lemr3 Jan Havlis4 Pavel Pec 1 w w B w 4 B B Bb B B w B F B w B B BB B B B B BB B B B B B B BB B BB B B B B BB B B BB BB B B BB BB BB B B BBB B BB B B BB B B B B IV Bb B B B B Bb w B B B B Bb w BB B B BB Chunhua Qiao5 and Lawrence M. Sayre5 1 Department of Biochemistry 2Laboratory of Growth Regulators and 3Department of Analytical Chemistry Faculty of Science Palackỷ University Olomouc Czech Republic 4Department of Analytical Chemistry Faculty of Science Masaryk University Brno Czech Republic 5Department of Chemistry Case Western Reserve University Cleveland OH USA 1 5-Diamino-2-pentyne DAPY was found to be a weak substrate of grass pea Lathyrus sativus GPAO and sainfoin Onobrychis viciifolia OVAO amine oxidases. Prolonged incubations however resulted in irreversible inhibition of both enzymes. For GPAO and OVAO rates of inactivation of min-1 were determined the apparent K values half-maximal inactivation were of the order of 10-5 M. DAPY was found to be a mechanism-based inhibitor of the enzymes because the substrate cadaverine significantly prevented irreversible inhibition. The N1-methyl and N5-methyl analogs of DAPY were tested with GPAO and were weaker inactivators especially the N5-methyl than DAPY. Prolonged incubations of GPAO or OVAO with DAPY resulted in the appearance of a yellow-brown chromophore kmax 310-325 nm depending on the working buffer . Excitation at 310 nm was associated with emitted fluorescence with a maximum at 445 nm suggestive of extended conjugation. After dialysis the color intensity was substantially decreased indicating the formation of a low molecular mass secondary product of turnover. The compound provided positive reactions with ninhydrin 2-aminobenzalde-hyde and Kovacs reagents suggesting

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