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Amylase

About: Amylase is a research topic. Over the lifetime, 14164 publications have been published within this topic receiving 296069 citations.


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Journal ArticleDOI
TL;DR: This study presents the first evidence that the BE isoforms differ in their action on amylopectin, and the implication of these findings to the mechanism of amylipectin synthesis in vivo is discussed.
Abstract: The multiple forms of branching enzyme (BE) from developing maize (Zea mays) endosperm were purified by modification of previous procedures such that amylase activity could be eliminated completely from the BE preparation. Three distinct assays for BE activity (phosphorylase a stimulation assay, BE linkage assay, and iodine stain assay) were used to characterize and differentiate the properties of the BE isoforms. This study presents the first evidence that the BE isoforms differ in their action on amylopectin. BEI had the highest activity in branching amylose, but its rate of branching amylopectin was less than 5% of that of branching amylose. Conversely, BEII isoforms had lower rates in branching amylose (about 9–12% of that of BEI) and had higher rates of branching amylopectin (about 6-fold) than BEI. The implication of these findings to the mechanism of amylopectin synthesis in vivo are discussed.

257 citations

Journal ArticleDOI
TL;DR: High levels (2-565 units/g) of amylase activity were observed in human faeces, and mixed populations of gut bacteria rapidly fermented starch with the production of volatile fatty acids and organic acids.
Abstract: High levels (2-565 units/g) of amylase activity were observed in human faeces. Over 92% of amylase activity in faeces obtained from healthy persons was extracellular, whereas only about 9% of activity was associated with particulate material and washed cells. Bacterial cell-bound amylases were considerably more efficient in breaking down starch, however, than were the soluble enzymes which occurred in cell-free faecal supernatant fluids. Cell population densities of anaerobic starch-hydrolysing bacteria in the stools of ten persons ranged from 1.1 X 10(10) to 3.3 X 10(12)/g of faeces. Identification of 120 starch-hydrolysing colonies isolated from the stools of six subjects showed that the predominant amylolytic bacteria belonged to the genera Bifidobacterium, Bacteroides, Fusobacterium and Butyrivibrio. Mixed populations of gut bacteria rapidly fermented starch with the production of volatile fatty acids and organic acids. Lactate was observed to be a major, though transient intermediate during starch fermentation by these cultures. Approximately 60% of starch utilized was converted to volatile fatty acids, which in the human colon would be potentially available for absorption.

257 citations

Journal ArticleDOI
TL;DR: The chemical forms and resistance to hydrolysis in vitro of raw and gelatinised starch from peas, maize, wheat and potatoes were measured as discussed by the authors, and the onset of resistance to starch-hydrolysis was confirmed using a simulated digestion technique.

255 citations

Book ChapterDOI
01 Jan 1974
TL;DR: The present findings suggest that the hydrolysis of the polysaccharide chain occurs via the principle of ″multiple attack―, that is, once the enzyme-substrate complex is formed, the enzyme can hydrolyze several bonds of the polymer successively before the enzyme is again liberated in the free form.
Abstract: Publisher Summary This chapter explains α-amylase, which hydrolyses α-14-glucan bonds in polysaccharides, such as starch, amylopectin and glycogen, and their degradation products with a chain length of at least 3 d-glucose residues. Damage to the α-amylase synthesizing tissues, in particular the pancreas, results in leakage of the enzyme from the parenchymal cells and its appearance in the serum. The present findings suggest that the hydrolysis of the polysaccharide chain occurs via the principle of ″multiple attack―, that is, once the enzyme-substrate complex is formed, the enzyme can hydrolyze several bonds of the polymer successively before the enzyme is again liberated in the free form. The amylase activity can be measured by means of the decrease in viscosity of a starch solution, the decrease in turbidity of a starch suspension, the decrease in the intensity of the starch-iodine reaction and the increase in the number of reducing groups. On the basis of the starch-iodine reaction it was concluded that iso-amylases occurred in all five serum fractions as separated by electrophoresis. α-amylase is applied in biochemistry, clinical chemistry and pharmacy.

254 citations

Journal ArticleDOI
TL;DR: Zymograms of larval extracts indicated that exogenous food has more a qualitative than a quantitative role in the secretion of digestive enzymes in this species.
Abstract: The evolution of the digestive enzyme equipment in seabream from hatching to 30 days old larvae was studied; there was a progressive increase in the activity of protease, amylase and acid and alkaline phosphatase from day 15 onwards. The use of specific inhibitors, and SDS-PAGE provided evidence to suggest that most of the proteases belonged to the serine group. A high α-amylase activity was also denoted. Zymograms of larval extracts indicated that exogenous food has more a qualitative than a quantitative role in the secretion of digestive enzymes in this species.

253 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20241
2023460
2022976
2021308
2020347
2019328