Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.4.1.18 (branching enzyme)
 628 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This study reports the identification of a new class of cassava (Manihot esculenta Crantz) with a storage root showing unusual free sugar accumulation and novel starch. Twenty-seven clones high in free sugar were identified under cultivation in primitive rural community areas in the Amazon. Iodine test and glucose oxidase-peroxidase reagent strips were used, in the field, for identification of starch and glucose, respectively. Five out of these 27 clones of cassava were cultivated at EMBRAPA Genetic Resources and Biotechnology and used for biochemical characterization, starch synthesis enzyme activities and gene expression analysis. Carbohydrates were fractioned into free sugar, polymerized water-soluble and -insoluble alpha-polyglucan. Clones of series CAS36 accumulate over 100 times more free sugar (mainly glucose) than commercial varieties. Monosaccharide composition analysis revealed one clone with distinct water-soluble sugars not present in the commercial cultivar. Structure analysis of the water-soluble and -insoluble alpha-polyglucan revealed the presence of a glycogen-like starch in clone CAS36.1. This clone indicated disruption in the starch synthesis pathway for enzyme activities and protein blot analyses in ADPG-pyrophosphorylase and branching enzyme, and their corresponding protein. Gene expression analysis indicated the lack of transcript for the gene coding for branching enzyme, but not for the gene coding for the ADPG-pyrophosphorylase small subunit. In addition, the pattern of distribution of sugar and starch content showed to be related to tissue age in the storage root.
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PMID:Identification and characterization of a novel cassava (Manihot esculenta Crantz) clone with high free sugar content and novel starch. 1563 Jun 25

The amylose content of rice caryopsis is determined by Wx protein, one kind of granule-bound starch synthetase which is encoded by Wx gene. Different rice types and species have different levels of Wx gene expression and have different amylose contents in their caryopsis. Wuyunjing No.7 (2200), the japonica rice with an amylose content 17% and its transgenic rice lines with antisense Wx gene (2201 and 2203, with amylose contents 8.5% and 2% respectively), and Longtefu (LP03), the indica rice with a high amylose content (28%) and its transgenic rice with antisense Wx gene (A199, with an amylose content 9%) were used to investigate the effects of Wx protein content decrease on the activities of enzymes involved in starch synthesis and thereby starch accumulation. The results indicated that with the decrease in Wx protein, the amylose content in transgenic caryopsis was reduced accordingly, whereas the amylopectin content per caryopsis (mg/grain) was not affected, and made the total starch content in transgenic caryopsis markedly lower than their parents. With the development of caryopsis, the amylose/total starch ratio was not changed significantly in the two parent caryopses, LP03 and 2200, but it went down gradually in their transgenic caryopses. The amylose/total starch ratio in transgenic caryopses was very significantly lower than their parents in the same period. The activities of ADP-glucose pyrophosphorylase (ADPG-PPase), granule-bound starch synthase (GBSS), soluble starch synthase (SSS) and starch branching enzyme (SBE) rose rapidly in early periods of grain filling, and soon reached their maximum, then reduced quickly until the middle and later periods of grain filling. Compared with the parents, the GBSS activity in transgenic caryopsis was significantly lowered, and correlated with the amylose reduction. Besides, the maximum activity of GBSS appeared earlier, and the range of the activity was smaller. In transgenic caryopsis, the activities of ADPG-PPase and SSS were higher than their parents in early and middle periods of grain filling, while the SBE activity was higher than their parents in middle and late periods.
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PMID:[Changes in the activities of enzymes involved in starch synthesis and accumulation in caryopsis of transgenic rice with antisense Wx gene]. 1662 21

Methods for the formation of protoplasts from developing maize endosperm and for the aqueous isolation of intact amyloplasts from such protoplasts are described. Protoplasts were obtained after incubating endosperm slices in a medium containing cellulase and pectolyase for 5 days at 4 degrees C or 5 hours at 30 degrees C. After purification in a Ficoll density gradient, the protoplasts were reptured by forcing the suspension through a Nitex mesh (20 micrometer) positioned at the lower end of a modified disposable syringe. The resulting filtrate was layered on a discontinuous Ficoll density gradient of 30, 15, and 10%. Each Ficoll solution contained 0.7 molar sucrose, 10 millimolar arginine, 10 millimolar dl-dithiothreitol, 50 millimolar 2-(N-morpholino)ethanesulfonic acid (pH 5.6), and 2 millimolar CaCl(2). After 3 hours in the cold, an amyloplast fraction 50 to 93% intact and free from cytoplasmic, mitochondrial, and glyoxysomal contamination was recovered in the 15% Ficoll layer. Amyloplast intactness was estimated by fluorescent microscopy and activity of certain amyloplast marker enzymes before and after rupture of the amyloplast membrane. Starch branching enzyme, ADPG-pyrophosphorylase, and nitrite reductase were used as amyloplast marker enzymes.
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PMID:Isolation of amyloplasts from developing maize endosperm. 1666 89

Amylose, amylopectin and starch dynamic accumulation and key enzymes activities in the grains of 4 maize inbred lines (two high-starch ones and two low-starch ones) were studied. The amounts of amylose, amylopectin and starch in the grains of 4 maize inbred lines increased as sigmoid curves during grain filling period. The changes in amylose, amylopectin and starch accumulation rates followed single-peaked curves, and reached their peaks in the 25-30 days after pollination (DAP). Changes in activities of adenosine diphosphoglucose pyrophosphorylase (ADPG-PPase, EC 2.7.7.27), soluble starch synthase (SSS, EC 2.4.1.21) and starch granule-bound synthase (GBSS, EC 2.4.1.21) in the grains of 4 inbred lines appeared single-peaked curves with the peaks appearing 20-30 DAP. Changes in activities of starch-branching enzyme (Q-enzyme, EC 2.4.1.18) in the grains of high-starch inbred lines appeared single-peaked curves with the peak values at 20 DAP, while the two low-starch inbred lines showed double-peaked curves with the peak values in the 15-20 DAP and 30-35 DAP. There was significant correlation between ADPG-PPase, SSS and GBSS activities. The results indicated that the Q-enzyme had different expression in high- and low-starch maize inbred lines, and verified that ADPG-PPase, SSS and GBSS activities were significantly and positively correlated with amylose, amylopectin and starch accumulation rates.
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PMID:Starch accumulation and activities of key enzymes involved in starch synthesis in the grains of maize inbred lines with different starch contents. 1745 97