0000000000162811
AUTHOR
B. Schöbel
Isolation and characterization of a chlorogenic acid esterase from Aspergillus niger.
Abstract The isolation and characterization of a specific chlorogenic acid esterase is described. The enzyme activity is measured by determination of the hydrolysis product caffeic acid. The enzyme had been concentrated by means of ultrafiltration and column-chromatography. The pH- and temperature optimum were 6.5 and 45 °C respectively. Divalent cations were not required for the enzyme activity. As other esterases, this enzyme is inhibited by di-isopropyl-phosphorofluoridate. The Km-value is 0.70 mᴍ chlorogenic acid, the molecular weight 240000. The described enzyme is specific for chlorogenic acid. On the other hand a typical unspecific esterase like the pig liver esterases does not split…
Isolierung und Charakterisierung einer Acetylester-Hydrolase aus Aspergillus rtiger / Isolation and Characterization of an Acetylester-Hydrolase from Aspergillus niger
Abstract The characteristic features of an acetic acid esters hydrolyzing enzyme (acetylesterase, EC 3.1.1.16) are described. The pH- and temperature optimum were 7.0 and 40 °C respectively. The stability of the enzyme regarding different pH- and temperature conditions was investigated. The molecular weight of the acetylesterase could be determined to 160000. A small acetic ester hydrolyzing activity was found too with a molecular weight of about 25000. The activity was not inhibited by addition of di-isopropylphosphorofluoridate (DFP) or physostigmine. The KM-value for glyceryl triacetate was about 90 mM. Concentration of the enzyme was done by ultrafiltration and column-chromatography. Th…
Climate associated variations in the human serum albumin level.
Quantitative determinations of the human serum albumin level showed significantly higher values in tropical (Negroes 46.98 mg/ml, Indians 54.30 mg/ml) than in non-tropical populations (Germans 44.41 mg/ml). These observations are in agreement with those of several other authors. It is assumed that these variations in the serum albumin level are related to climate, and that they may indicate some biological advantage of higher albumin levels under the climatic conditions of tropical biotops. This hypothesis is discussed considering several aspects.