Acid α-D-glucosidases from plant sources

Marshall, J.J.; Taylor, Pamela M.

doi:10.1016/0006-291x(71)90084-2

Cited by 19 publications

(6 citation statements)

References 18 publications

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“…Hydrolytic activity on raffinose and maltose but not on sucrose at pH 4.5 indicates the absence of an acid invertase but the presence of an ac-galactosidase and an a-glucosidase (Table I) but activities of this enzyme in other plants show pH optima of 3.5 to 5.5 (5,11). Acid a-glucosidase activity has been reported previously in sweet corn (12) and alfalfa (8). The occurrence of an acid a-glucosidase in sugar beet root is surprising but may indicate a genetic carryover from the starch-storing ancestors of the sugar beet.…”

Section: Resultsmentioning

confidence: 58%

Enzymes Involved in the Postharvest Degradation of Sucrose in Beta vulgaris L. Root Tissue

Wyse¹

1974

Plant Physiol.

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The reducing sugar content of sugar beet (Beta vulgaris L.) roots increased during 30 days of storage at 21 C and 160 days at 5 C as a result of an increase in acid invertase activity. Sucrose synthetase and neutral invertase activities were high at harvest but declined during storage, thus showing no relationship with postharvest reducing sugar accumulation in sugar beet roots. Acid a-glucosidase activity was detected in fresh roots but showed no activity with sucrose as a substrate.The sucrose content of sugar beet roots declines after harvest as a result of sucrose conversion to reducing sugars and oligosaccharides (20). At storage temperatures above 5 C reducing sugars (glucose and fructose) accumulate, while at temperatures below 5 C both raffinose and reducing sugars accumulate (20). The objective of this study was to determine which enzymes are involved in sucrose degradation in sugar beet roots during storage.Acid invertase activity is normally very low in fresh sugar beet roots, but induction of invertase activity by aging beet disks in water has been well documented (1,15,19 operations were carried out at 0 to 5 C. Roots were peeled, diced, and homogenized in a VirTis homogenizer' with an equal w/v ratio of grinding medium (0.05 M potassium phosphate, pH 7.2; 0.1 mm EDTA; 1 mM 2-mercaptoethanol; 10 mM Na2SO.). The homogenate was strained through two layers of dacron ninon and centrifuged at 16,000g for 20 min. The supernatant liquid was dialyzed overnight against 10 volumes of either grinding medium for neutral invertase and sucrose synthetase assays, or acetate buffer (0.05 M acetate, pH 5.0; 0.1 mM EDTA; 1 mm 2-mercaptoethanol; 10 mm Na,SO8) for acid invertase assay. The extract dialyzed at pH 5 was centrifuged at 1 6,000g for 10 min before assay and the pellet discarded.Assay. The standard assay mixture for neutral invertase contained 0.16 ml of buffer (8 ltmoles of potassium phosphate, pH 7.2; 0.016 lumole EDTA; 80 jumoles of sucrose) and 0.04 ml of the enzyme preparation. Normal assay time was 30 min at 35 C. Assay mixtures for sucrose synthetase were the same as for neutral invertase except that 10 ,u1 of 0.05 M UDP were added and only 0.03 ml of the enzyme preparation was used. Assay mixtures for acid invertase were the same as for neutral invertase except that the phosphate buffer was replaced by acetate at pH 5.0. The reactions were stopped by adding 1 ml of Somogyi's (18) copper reagent and reducing sugars determined by the method of Nelson (14). Glucose liberation, in assays in which maltose was the substrate, was determined by the glucose oxidase/peroxidase method with a commercial reagent (Glucostat, Worthington2).Protein was determined by the method of Lowry (9). The reducing sugar content of the stored roots was determined on a clarified extract prepared by the method of Dexter et al. (4). RESULTS AND DISCUSSIONIn a preliminary experiment a survey of enzymes which may degrade sucrose in fresh sugar beet roots was made. Sucrose, raffinose, and maltose were used as substrates and a...

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Section: Resultsmentioning

confidence: 58%

Enzymes Involved in the Postharvest Degradation of Sucrose in Beta vulgaris L. Root Tissue

Wyse¹

1974

Plant Physiol.

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“…The third group is characterized as a-glucosidases possessing glucoamylase activity, which have been found in mammalian tissues [18][19][20][21][22][23][24][25] , in plant seeds, [26][27][28][29][30][31] in Mucor species 351 and in Candida species. 321 However, the substrate specificity of this group may be classified into category of the second group, except that the a-glucosidases are capable of attacking glycogen and soluble starch.…”

Section: Effect Of Substrate Concentrationmentioning

confidence: 99%

Substrate Specificity ofSaccharomyces logos α-Glucosidase

Chiba¹,

Saeki²,

Shimomura³

1973

Agricultural and Biological Chemistry

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“…The enzyme a-glucosidase (a-D-glucoside glucohydrolase; EC 3.2.1.20) has been reported to occur in animals (11), plants (14), molds, yeasts, and fungi (3,23,26,31). Although a number of studies on bacterial a-glucosidases have been carried out (1,2,10,17,24,25,28,30), there is a paucity of information on the a-glucosidase from Lactobacillus sp.…”

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confidence: 99%

Production and properties of alpha-glucosidase from Lactobacillus acidophilus

Li¹,

Chan²

1983

Appl Environ Microbiol

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Lactobacillus acidophilus IFO 3532 was found to produce only intracellular aglucosidase (a-D-glucoside glucohydrolase; EC 3.2.1.20). Maximum enzyme production was obtained in a medium containing 2% maltose as inducer at 37°C and at an initial pH of 6.5. The enzyme was formed in the cytoplasm and accumulated as a large pool during the logarithmic growth phase. Enzyme production was strongly inhibited by 4 ,uM CuSO4, 40 ,uM CoCl2, and beef extract; MnSO4 and the presence of proteose peptone and yeast extract in the medium greatly enhanced enzyme production. A 16.6-fold purification of aglucosidase was achieved by (NH4)2SO4 fractionation and DEAE-cellulose column chromatography. The enzyme showed high specificity for maltose. The Km for a-p-nitrophenyl-,3-D-glucopyranoside was 11.5 mM, and the Vmax for a-pnitrophenyl-3-D-glucopyranoside hydrolysis was 12.99 ,umol/min per mg of protein. The optimal pH and temperature for enzyme activity were 5.0 and 37°C, respectively. The enzyme activity was inhibited by Hg2+, Cu2+, Ni2+, Zn2+, Ca +, Co2, urea, rose bengal, and 2-iodoacetamide, whereas Mn2+, Mg2+, Lcysteine, L-histidine, Tris, and EDTA stimulated enzyme activity. Transglucosylase activity was present in the partially purified enzyme, and isomaltose was the only glucosyltransferase product. Amylase activity in the purified preparation was relatively weak, and no isomaltase activity was detected.

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Acid α-D-glucosidases from plant sources

Cited by 19 publications

References 18 publications

Enzymes Involved in the Postharvest Degradation of Sucrose in Beta vulgaris L. Root Tissue

Enzymes Involved in the Postharvest Degradation of Sucrose in Beta vulgaris L. Root Tissue

Substrate Specificity ofSaccharomyces logos α-Glucosidase

Production and properties of alpha-glucosidase from Lactobacillus acidophilus

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