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245	1	0	_aPurification and characterization of polyphenol oxidase from nettle (Urtica dioica L.)and inhibitory effects of some chemicals on enzyme activity
490	0		_vJournal of Enzyme Inhibition and Medicinal Chemistry, 20(3), p.297-302, 2005
520	3		_aPolyphenol oxidase (PPO)of nettle (Urtica dioica L.)was extracted and purified through (NH4)2SO4 precipitation, dialysis, and CM-Sephadex ion-exchange chromatography and was used for its characterization. The PPO showed activity to catechol, 4-methylcatechol, L-3,4-dihydroxyphenylalanine (L-DOPA), L-tyrosine, p-cresol, pyrogallol, catechin and trans-cinnamic acid. For each of these eight substrates, optimum conditions such as pH and temperature were determined and L-tyrosine was found to be one of the most suitable substrates. Optimum pH and temperature were found at pH 4.5 and 308C respectively and Km and Vmax values were 7.90 £ 1024 M, and 11290 EU/mL for with L-tyrosine as substrate. The inhibitory effect of several inhibitors, L-cysteine chloride, sodium azide, sodium cyanide, benzoic acid, salicylic acid, L-ascorbic acid, glutathione, thiourea, sodium diethyl dithiocarbamate, b-mercaptoethanol and sodium metabisulfite were tested. The most effective was found to be sodium diethyl dithiocarbamate which acted as a competitive inhibitor with a Ki value of 1.79 £ 1029 M. In addition one isoenzyme of PPO was detected by native polacrylamide slab gel electrophoresis.
650	1	4	_aPOLYPHENOL OXIDASE
650	1	4	_aENZYME
650	1	4	_aNETTLE
650	1	4	_aURTICA DIOICA L
700	1	2	_aGulcin, I.
700	1	2	_aKufrevioglu, O.I.
700	1	2	_aOktay, M.
856	4	0	_uhttps://drive.google.com/file/d/1RXwp3g5oBGmGiQlbz-I0ayknXRTRyyhk/view?usp=drivesdk _zPara ver el documento ingresa a Google con tu cuenta: @cicy.edu.mx
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