Studies on Starch‐Degrading Enzymes. Part VII. Properties and Action‐Pattern of the α‐Amylases from Barley, Oats, Rye and Wheat

Greenwood, C. T.; Milne, Elspeth

doi:10.1002/star.19680200402

Cited by 42 publications

(11 citation statements)

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“…In sorghum (8), rice (23), maize (9), and pea (13) a-amylase activity did not appear until the germination process had started. In agreement with our results, a-amylase has been found also in resting seeds of rye (10), oats (10), barley, and wheat (11).…”

Section: Discussionsupporting

confidence: 82%

Starch Degradation in the Cotyledons of Germinating Lentils

Tárrago¹,

Nicolás²

1976

Plant Physiol.

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Starch, total amylolytic and phosphorylase activities were determined in lentil cotyledons during the first days of germination. Several independent criteria show that the amylolytic activity is due mainly to an amylase of the a type. Starch is degraded slowly in the first days; during this time, a-and 13-amylase activity are very low, while phosphorylase increases and reach a peak on the 3rd day. On the 4th day, ther. is a more rapid depletion of starch which coincides with an increase in aamylase activity. By polyacrylamide gel electrophoresis of the crude starch-degrading enzyme, five bands were obtained: one phosphorylase, three a-amylases, and one /3-amylase. Based on their heat lability or heat stability, two sets of a-amylase seem to exist in lentil cotyledons.The enzymic degradation of starch in higher plants is due mainly to the phosphorylases and the amylases. They have been studied particularly in seeds, where they are responsible for the breakdown of polysaccharide reserves. Much of our knowledge of starch degradation during seed germination comes from studies with cereals (6,7,15,16,18,19,23) where a number of amylase isozymes have been described. In contrast, available knowledge of starch catabolism in legumes is very limited and almost reduced to the studies with germinating peas (13,(20)(21)(22).The major aim of the work presented here was to determine the mechanism of breakdown of reserve starch in the cotyledons of germinating lentil seeds, in order to improve our knowledge of the carbohydrate catabolism in this group of higher plants. Analyses of starch and activities of starch-degrading enzymes were carried out during the course of germination. Phosphorylases and amylases were separated by polyacrylamide gel electrophoresis to obtain information about the various starch-degrading enzymes of germinating lentil seeds. MATERIALS AND METHODSLentil seeds (Lens culinaris, Medik = Lens esculenta, Moench) were soaked for 4 hr in a disinfectant solution (0.12% Orthocide-50 wettable, a commercial fungicide) at room temperature. The seeds were then germinated in the dark at 25 C on moist filter paper in Petri dishes for different periods of time, and then separated into cotyledons and embryos. Only the cotyledons were used for all subsequent assays. All operations were performed at 0 to 4 C unless indicated otherwise.Preparation of Crude Enzyme. The cotyledons (1 to 8/ml depending on the germination time) were homogenized with 20 ml of unbuffered distilled H20 in a Sorvall Omni-Mixer. The whole homogenate was strained through 2 layers of cheesecloth, and then centrifuged in a Sorvall RC2-B refrigerated centrifuge at 20,000g for 30 min at 2 C.In order to differentiate between a-and f8-amylase, the super-' Present address: Departamento de Fisiologia Vegetal, Universidad de Salamanca, Facultad de Ciencias, Spain. natant was treated selectively with 10 mm EDTA, 0.1 mM HgCl,, 3 mm CaCl2, and heated at 70 C in the presence of calcium ions.Amylase Assay. Two aliquots of the supernatant were removed...

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Section: Discussionsupporting

confidence: 82%

Starch Degradation in the Cotyledons of Germinating Lentils

Tárrago¹,

Nicolás²

1976

Plant Physiol.

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“…This work has served to highlight the large impact that even very low levels of α-amylase activity can have on interpretation of pasting data from flour samples. Inactivation of α-amylase can also be achieved at pH values >8.5 (Greenwood andMilne 1968, Barnes andBlakeney 1974). As a result of this, and due to the relevance to the product under investigation, only ARVA results will be used for comparisons with alkaline noodle texture results (Bhattacharya and Corke 1996).…”

Section: Rva Pasting Propertiesmentioning

confidence: 99%

Physicochemical Properties of Australian Flours Influencing the Texture of Yellow Alkaline Noodles

Ross¹,

Quail²,

Crosbie

1997

Cereal Chem

113

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Cereal Chem. 74(6):814-820Flour properties of 25 Australian wheat cultivars were examined for their relationship to alkaline noodle quality. Rapid Visco Analyzer (RVA) analyses of flours showed that RVA breakdown and final viscosity determined in both water and dilute sodium carbonate were significantly related to the alkaline noodle firmness, elasticity, and surface smoothness. Flour swelling volume (FSV) of flours was negatively correlated with alkaline noodle firmness and elasticity, and positively correlated with surface smoothness of cooked noodles. Use of a dilute sodium carbonate solution led to overall increases in both paste viscosity and FSV. High FSV and low RVA final viscosity values were associated with both the softest noodles and with cultivars containing a null allele for granulebound starch synthase on chromosome 4A. Flour protein content and SDS sedimentation volumes were significantly related to noodle texture. The relationship between protein content and noodle firmness was dependent on the Null4A status of the flours and suggested an interaction between starch and protein in determining noodle texture. Multiple regression analysis using flour protein and FSV accounted for 76% of the variation in alkaline noodle firmness. A speculative model of noodle structure was developed based on a concept of the cooked noodle as a composite material.

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“…Kinetic studies have shown that there is no significant difference in an open system as detected by TGA (Koga 1995;Soares et al 2005;Guinesi et al 2006). There have been several reports of studies of the degradation pattern of starch from different sources based on the differential thermal analysis (Greenwood and Milne 1968;Aggarwal and Dollimore 1996;Guinesi et al 2006). Dehydration and decomposition have generally been considered as the main two processes associated with the degradation mechanisms of starch in an open system (Aggarwal and Dollimore 1998;Ruseckaite and Jiménez 2003;Soares et al 2005).…”

mentioning

confidence: 99%

Thermal Decomposition of Corn Starch with Different Amylose/Amylopectin Ratios in Open and Sealed Systems

Liu

et al. 2009

Cereal Chem

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Cereal Chem. 86(4):383-385Thermal decomposition of corn starches with different amylose to amylopectin ratios (0:100 waxy, 23:77 maize, 50:50 Gelose 50, 80:20 Gelose 80) were studied by thermogravimetric analysis (TGA) in an open system and differential scanning calorimetry (DSC) in a sealed system using stainless steel high-pressure pans with varying water content (9-75%). The initial water content did not affect the decomposition temperature in the open system because all water evaporated from samples before reaching the decomposition temperature. The sequence of decomposition temperature of different starches is waxy > maize > G50 > G80 in an open system. The moisture content in starch remains constant during the deg-radation process in a sealed system. Two decomposition temperatures were observed in the sealed system: the first at lower temperature represents long chain scission and the second at higher temperature involves decomposition of the glucose ring. The sequence of the first degradation is waxy > maize > G50 > G80. There is no observable difference of the second degradation for the samples containing different amylose to amylopectin ratios. The higher the moisture content, the lower the second decomposition temperature. Decomposition of glucose was used to confirm the mechanisms proposed for the starch degradation.

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Studies on Starch‐Degrading Enzymes. Part VII. Properties and Action‐Pattern of the α‐Amylases from Barley, Oats, Rye and Wheat

Cited by 42 publications

References 28 publications

Starch Degradation in the Cotyledons of Germinating Lentils

Starch Degradation in the Cotyledons of Germinating Lentils

Physicochemical Properties of Australian Flours Influencing the Texture of Yellow Alkaline Noodles

Thermal Decomposition of Corn Starch with Different Amylose/Amylopectin Ratios in Open and Sealed Systems

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