Properties of potato α-glucosidase

Killilea, S.Derek; Clancy, Mary J.

doi:10.1016/s0031-9422(00)94604-1

Cited by 15 publications

(5 citation statements)

References 25 publications

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“…Method A: 0.3 ml of extract was mixed with 1 ml of 1 g á l A1 4-nitrophenyl-a-D-glucopyranoside in 50 mM Na-acetate (pH 5.0) and incubated at 25°C. Samples were taken at intervals and boiled for 2 min, and optical density was determined at 400 nm (Killilea and Clancy 1978). Method B: 50 ll of extract was mixed with 250 ll of 50 mM maltose, 50 mM Naacetate (pH 5.0) and incubated at 25°C.…”

Section: Methodsmentioning

confidence: 99%

Starch metabolism in developing embryos of oilseed rape

Silva

Eastmond

Hill

et al. 1997

Planta

112

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The aim of this work was to characterise the metabolism of starch in developing embryos of oilseed rape (Brassica napus L. cv. Topaz). The accumulation of starch in embryos in siliques which were darkened or had been exposed to the light was similar, suggesting that the starch is synthesised from imported sucrose rather than via photosynthesis in the embryo. Starch content and the activities of plastidial enzymes required for synthesis of starch from glucose 6-phosphate (Glc6P) both peaked during the early-mid stage of cotyledon development (i.e. during the early part of oil accumulation) and then declined. The mature embryo contained almost no starch. The starch-degrading enzymes a-(EC 3.2.1.1) and b-amylase (EC 3.2.1.2) and phosphorylase (EC 2.4.1.1) were present throughout development. Most of the activity of these three enzymes was extraplastidial and therefore unlikely to be involved in starch degradation, but there were distinct plastidial and extraplastidial isoforms of all three enzymes. Activity gels indicated that distinct plastidial isoforms increase during the change from net synthesis to net degradation of starch. Plastids isolated from embryos at stages both before and after the maximum starch content could convert Glc6P to starch although the rate was lower at the later stage. The results are consistent with the idea that starch synthesis and degradation occur simultaneously during embryo development. The possible roles of transient starch accumulation during embryo development are discussed.

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Section: Methodsmentioning

confidence: 99%

Starch metabolism in developing embryos of oilseed rape

Silva

Eastmond

Hill

et al. 1997

Planta

112

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“…Examples of acid α-glucosidases (pH optimum 4-5) include those isolated from banana pulp tissue (Konishi et al, 1992); from the seeds of barley (Sun and Henson, 1990); buckwheat (Kanaya et al, 1976); flint corn (Chiba and Shimomura, 1975); green gram (Yamasaki and Suzuki, 1979); peas (Beers et al, 1990); rice (Takahashi et al, 1971); sugar beet (Yamasaki and Konno, 1991); and Welsh onion (Suzuki and Uchida, 1984). Neutral isoforms of α-glucosidase (pH optimum 6-7) have been isolated from potato tubers (Killilea and Clancy, 1978), banana pulp tissue (Konishi et al, 1992) and also from pea chloroplasts (Sun et al, 1995).…”

Section: Introductionmentioning

confidence: 99%

cDNA cloning and characterisation of an α‐glucosidase gene from potato (Solanum tuberosum L.)

Taylor¹,

George²,

Ross³

et al. 1998

The Plant Journal

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SummaryUsing an Arabidopsis thaliana expressed sequence tag with sequence similarity to human lysosomal α-glucosidase as a probe, a potato cDNA was isolated. The cDNA encodes a polypeptide with an Mr value of 105,400 and the most significant matches of the deduced amino acid sequence are with members of family 31 of glucosyl transferase. The potato cDNA was expressed in a strain of Saccharomyces cerevisiae that is deficient in maltase activity and unable to grow using maltose as a carbon source (ABYSMAL81). Expression of the potato cDNA in the mutant yeast strain restores its ability to use maltose as a carbon source for growth. Additionally, α-glucosidase activity could be measured in extracts of the yeast cells following complementation. A range of maltodextrins were substrates for this activity. The steady-state expression level of the potato α-glucosidase gene was low in most tissues examined, the highest levels occurring in sprouting tubers and source leaves.

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“…A range of starch-degrading enzyme activities have been reported in potato tubers, including a-amylase, isoamylase, p-amylase, a-glucosidase, and phosphorylase (Gerbrandy et al, 1975;Kennedy and Isherwood, 1975;Fan, 1975;Killilea and Clancy, 1978;Schneider et al, 1981;Cochrane et a]., 1991aCochrane et a]., , 1991bCottrell et a]., 1993). However, it is not clear whether the degradation is primarily amylolytic or phosphorolytic.…”

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confidence: 99%