Document Detail


Purification and characterization of polyphenol oxidase from nettle (Urtica dioica L.) and inhibitory effects of some chemicals on enzyme activity.
MedLine Citation:
PMID:  16119202     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Polyphenol 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 30 degrees C respectively and Km and Vmax values were 7.90 x 10(-4) 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, beta-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 x 10(-9)M. In addition one isoenzyme of PPO was detected by native polacrylamide slab gel electrophoresis.
Authors:
Ilhami Güllçin; O Irfan Küfrevioğlu; Münir Oktay
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of enzyme inhibition and medicinal chemistry     Volume:  20     ISSN:  1475-6366     ISO Abbreviation:  J Enzyme Inhib Med Chem     Publication Date:  2005 Jun 
Date Detail:
Created Date:  2005-08-25     Completed Date:  2005-12-02     Revised Date:  2007-03-21    
Medline Journal Info:
Nlm Unique ID:  101150203     Medline TA:  J Enzyme Inhib Med Chem     Country:  England    
Other Details:
Languages:  eng     Pagination:  297-302     Citation Subset:  IM    
Affiliation:
Atatürk University, Faculty of Science and Arts, Department of Chemistry, 25240, Erzurum, Turkey.
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MeSH Terms
Descriptor/Qualifier:
Ascorbic Acid / pharmacology
Catechol Oxidase / antagonists & inhibitors,  isolation & purification*,  metabolism,  pharmacology
Dithioerythritol / pharmacology
Ditiocarb / pharmacology
Enzyme Inhibitors / metabolism,  pharmacology
Enzyme Stability
Glutathione / pharmacology
Hydrogen-Ion Concentration
Kinetics
Potassium Cyanide / pharmacology
Sodium Azide / pharmacology
Substrate Specificity
Sulfites / pharmacology
Temperature
Thiourea / pharmacology
Urtica dioica / chemistry,  enzymology*
Chemical
Reg. No./Substance:
0/Enzyme Inhibitors; 0/Sulfites; 147-84-2/Ditiocarb; 151-50-8/Potassium Cyanide; 26628-22-8/Sodium Azide; 50-81-7/Ascorbic Acid; 62-56-6/Thiourea; 6892-68-8/Dithioerythritol; 70-18-8/Glutathione; 7681-57-4/sodium metabisulfite; EC 1.10.3.1/Catechol Oxidase

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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