title: Modification of tomato and Aspergillus niger pectinesterases with diethyl pyrocarbonate.
abstract: The role of histidine residues in pectinesterases was evaluated by monitoring the sensitivity to modification with diethyl pyrocarbonate in the tomato and Aspergillus niger enzymes. Different and incomplete losses of enzyme activity were obtained. Inactivation of the enzymes was proportional to the histidine content (two in the tomato T1 form, six in the Aspergillus form), suggesting that accessible histidine residues do not have active-site functions in these pectinesterases, but contribute to the overall structural stability. Lack of His roles in common between the enzyme forms is in agreement with the structures of pectinesterases having no conserved His residues.
authors.affiliation: Institute of Chemistry, Slovak Academy of Sciences, Bratislava, Slovakia.
authors.forename: O
authors.initials: O
authors.lastname: Markovic
authors.forename: J
authors.initials: J
authors.lastname: Stovícková
authors.forename: H
authors.initials: H
authors.lastname: Jörnvall
mesh_terms: D001234:Aspergillus niger / Q000201:enzymology; D002265:Carboxylic Ester Hydrolases / Q000737:chemistry* / Q000302:isolation & purification; D004047:Diethyl Pyrocarbonate / Q000737:chemistry*; D006639:Histidine / Q000032:analysis; D018551:Solanum lycopersicum / Q000201:enzymology; D013056:Spectrophotometry, Ultraviolet
chemical_list: D006639:Histidine; D002265:Carboxylic Ester Hydrolases; C022323:pectinesterase; D004047:Diethyl Pyrocarbonate