ß-Glucosidases(ßGL)-widely used in the enological field-are enzymes that catalyze the liberation of aromatic volatiles from their glycosidic precursors during winemaking.In the present study,aßGL obtain...ß-Glucosidases(ßGL)-widely used in the enological field-are enzymes that catalyze the liberation of aromatic volatiles from their glycosidic precursors during winemaking.In the present study,aßGL obtained from the Antarctic yeast Mrakia sp.LP 7.1.2016 was produced on a bioreactor scale,purified,characterized,and the enzyme’s properties studied for a potential enological application.Sodium-dodecylsulfate-polyacrylamide-gel electrophoresis indicated a high molecular weight for this enzyme,it having at least two subunits of 134 and 14 kDa.ßGL exhibited a pH optimum of 5.0 and retained substantial activity and stability at pH 4.0.The temperature range for optimal activity was 50-55℃,with the enzyme demonstrating thermostability up to 50℃ and retaining 87%of residual activity at that temperature after 3 h.The respective kinetic constants determined with p-nitrophenyl-ß-D-glucopyranoside and cellobiose were 0.38 and 1.79 mM for Km and 20.1 and 5.65μmol^(-1)mg^(-1)min^(.1) for Vmax,ß-Glucosidase manifested high activity in 10-25%(v/v)ethanol,30.0 mg L^(-1)sulfur dioxide,and 10-200 g L^(-1)fructose;but it was strongly inhibited by glucose,retaining only 6%of residual activity in the presence of 20 g L^(-1).Upon investigating the influence of the enzyme on Muscat-wine glycosidic precursors,we found significant differences in terpene content after 14 days ofßGL treatment at an eightfold increase over control-wine levels.The enzyme was more active toward the precursors of the monoterpenes nerol and geraniol and oxides of trans-and cis-linalool.These findings contribute to our understanding of the potential of cold-active enzymes in advantageous biotechnological applications to enology.展开更多
The objectives of the present survey were to study the production and the biochemical characterization of an enzymatic cold-active extract with polygalacturonase activity,to perform a first insight into its possible a...The objectives of the present survey were to study the production and the biochemical characterization of an enzymatic cold-active extract with polygalacturonase activity,to perform a first insight into its possible application in fruit-juice obtention process,and to use this juice for food products preparation.The enzymatic extract was produced by the Antarctic yeast Mrakia sp.LP January 7,2016 in a bioreactor with citric pectin as substrate.The polygalacturonase activity showed optimum conditions for reaction at 45◦C and pH 5.0.This activity was stable until 40◦C but deactivated at higher temperatures.Inhibition by Hg+2 suggested the presence of a thiol-dependent enzyme.A high-molecular polygalacturonase was detected in an SDS-PAGE and zymography analysis.Reaction-products were observed by thin-layer chromatography and suggested the endo-mode of action.The enzymatic extract had some accessory enzymes,such as pectin methylesterase,β-glucosidase,cellulase and inulinase.As a first insight into the potential use of this enzymatic extract for fruit maceration at mild temperatures,red and white dragon fruits were selected as models.At 23◦C,juice yields of 15%-23%higher than control were obtained after treatments,with a decrease of remanent solid of 25%-35%.The color of red dragon fruit juice increased with enzymatic treatment.Alginate balls that were prepared with the juices demonstrated a hardness of~10 N.The compression force of low-calorie sugar gels was 3.8 N.This work provided a complete study of the production,characterization,application and food product production using a new cold-active polygalacturonase extract of Antarctic origin.展开更多
基金supported by grants from the National Scientific and Technological Research Council and the National Agency for the Promotion of Science and Technology under Grants number PICT 2018-3194 and PICT 2019-3123.
文摘ß-Glucosidases(ßGL)-widely used in the enological field-are enzymes that catalyze the liberation of aromatic volatiles from their glycosidic precursors during winemaking.In the present study,aßGL obtained from the Antarctic yeast Mrakia sp.LP 7.1.2016 was produced on a bioreactor scale,purified,characterized,and the enzyme’s properties studied for a potential enological application.Sodium-dodecylsulfate-polyacrylamide-gel electrophoresis indicated a high molecular weight for this enzyme,it having at least two subunits of 134 and 14 kDa.ßGL exhibited a pH optimum of 5.0 and retained substantial activity and stability at pH 4.0.The temperature range for optimal activity was 50-55℃,with the enzyme demonstrating thermostability up to 50℃ and retaining 87%of residual activity at that temperature after 3 h.The respective kinetic constants determined with p-nitrophenyl-ß-D-glucopyranoside and cellobiose were 0.38 and 1.79 mM for Km and 20.1 and 5.65μmol^(-1)mg^(-1)min^(.1) for Vmax,ß-Glucosidase manifested high activity in 10-25%(v/v)ethanol,30.0 mg L^(-1)sulfur dioxide,and 10-200 g L^(-1)fructose;but it was strongly inhibited by glucose,retaining only 6%of residual activity in the presence of 20 g L^(-1).Upon investigating the influence of the enzyme on Muscat-wine glycosidic precursors,we found significant differences in terpene content after 14 days ofßGL treatment at an eightfold increase over control-wine levels.The enzyme was more active toward the precursors of the monoterpenes nerol and geraniol and oxides of trans-and cis-linalool.These findings contribute to our understanding of the potential of cold-active enzymes in advantageous biotechnological applications to enology.
基金supported by grants from the National Scientific and Technological Research Council and the National Agency for the Promotion of Science and Technology(ANPCyT,PICT 2018-3194 and PICT 2019-3123).
文摘The objectives of the present survey were to study the production and the biochemical characterization of an enzymatic cold-active extract with polygalacturonase activity,to perform a first insight into its possible application in fruit-juice obtention process,and to use this juice for food products preparation.The enzymatic extract was produced by the Antarctic yeast Mrakia sp.LP January 7,2016 in a bioreactor with citric pectin as substrate.The polygalacturonase activity showed optimum conditions for reaction at 45◦C and pH 5.0.This activity was stable until 40◦C but deactivated at higher temperatures.Inhibition by Hg+2 suggested the presence of a thiol-dependent enzyme.A high-molecular polygalacturonase was detected in an SDS-PAGE and zymography analysis.Reaction-products were observed by thin-layer chromatography and suggested the endo-mode of action.The enzymatic extract had some accessory enzymes,such as pectin methylesterase,β-glucosidase,cellulase and inulinase.As a first insight into the potential use of this enzymatic extract for fruit maceration at mild temperatures,red and white dragon fruits were selected as models.At 23◦C,juice yields of 15%-23%higher than control were obtained after treatments,with a decrease of remanent solid of 25%-35%.The color of red dragon fruit juice increased with enzymatic treatment.Alginate balls that were prepared with the juices demonstrated a hardness of~10 N.The compression force of low-calorie sugar gels was 3.8 N.This work provided a complete study of the production,characterization,application and food product production using a new cold-active polygalacturonase extract of Antarctic origin.
