Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “STARCH”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 955 records · Page 53Linked to original sources
PubMed2005

An in vivo study of the host response to starch-based polymers and composites subcutaneously implanted in rats.

Implant failure is one of the major concerns in the biomaterials field. Several factors have been related to the fail but in general these biomaterials do not exhibit comparable physical, chemical or biological properties to natural tissues and ultimately, these devices can lead to chronic inflammation and foreign-body reactions. Starch-based biodegradable materials and composites have shown promising properties for a wide range of biomedical applications as well as a reduced capacity to elicit a strong reaction from immune system cells in vitro. In this work, blends of corn starch with ethylene vinyl alcohol (SEVA-C), cellulose acetate (SCA) and polycaprolactone (SPCL), as well as hydroxyapatite (HA) reinforced starch-based composites, were investigated in vivo. The aim of the work was to assess the host response evoked for starch-based biomaterials, identifying the presence of key cell types. The tissues surrounding the implant were harvested together with the material and processed histologically for evaluation using immunohistochemistry. At implant retrieval there was no cellular exudate around the implants and no macroscopic signs of an inflammatory reaction in any of the animals. The histological analysis of the sectioned interface tissue after immunohistochemical staining using ED1, ED2, CD54, MHC class II and alpha/beta antibodies showed positively stained cells for all antibodies, except for alpha/beta for all the implantation periods, where it was different for the various polymers and for the period of implantation. SPCL and SCA composites were the materials that stimulated the greatest cellular tissue responses, but generally biodegradable starch-based materials did not induce a severe reaction for the studied implantation times, which contrasts with other types of degradable polymeric biomaterials.

Animals↗
PubMed1998

Purification and characterization of maize starch synthase I and its truncated forms.

Comparison of the protein sequences deduced from the cDNAs of maize granule-bound starch synthase, Escherichia coli glycogen synthase, and maize starch synthase I (SSI) reveals that maize SSI contains an N-terminal extension of 93 amino acids. In order to study the properties of maize SSI and to understand the functions of the maize SSI N-terminal extension, the gene coding for full-length SSI (SSI-1) and genes coding for N-terminally truncated SSI (SSI-2 and SSI-3) were individually expressed in E. coli. Here we describe for the first time the purification of a higher plant starch synthase to apparent homogeneity. Its kinetic properties were therefore studied in the absence of interfering amylolytic enzymes. The specific activities of the purified SSI-1, SSI-2, and SSI-3 were 22.5, 33.4, and 26.3 micromol Glc/min/mg of protein, respectively, which are eight times higher than those of partially purified SSI from developing maize endosperm. The full-length recombinant enzyme SSI-1 exhibited properties similar to those of the enzyme from maize endosperm. As observed for native maize enzyme, recombinant SSI-1 exhibited "unprimed" activity without added primer in the presence of 0.5 M citrate. Our results have clearly indicated that the catalytic center of SSI is not located in its N-terminal extension. However, N-terminal truncation decreased the enzyme affinity for amylopectin, with the Km for amylopectin of the truncated SSI-3 being about 60-90% higher than that of the full-length SSI-1. These results suggest that the N-terminal extension in SSI may not be directly involved in enzyme catalysis, but may instead regulate the enzyme binding of alpha-glucans. Additionally, the N-terminal extension may play a role in determining the localization of SSI to specific portions of the starch granule or it may regulate its interactions with other enzymes involved in starch synthesis.

Amino Acid Sequence↗
PubMed2000

Purification and characterization of soluble starch synthases from maize endosperm.

This study identified and characterized the soluble starch synthase of maize endosperm that was initially revealed as the SSII activity peak in anion exchange chromatography (J. L. Ozbun et al. (1971) Plant Physiol. 48, 765-769). At least six different genes coding for starch synthases are expressed in maize, although previously it was not known which of these is responsible for the SSII activity peak. The enzyme activity in the SSII peak was neutralized to a large extent by antibodies raised against the product of the Du1 gene, but was not affected by antibodies specific for the other highly expressed soluble starch synthase, zSSI, or for the zSSIIa or zSSIIb isoforms. These data provide direct evidence that Du1 codes for the starch synthase responsible for the SSII activity peak. This starch synthase was purified approximately 350-fold from endosperm extracts. The following enzymatic properties of the SSII activity were determined: temperature optimum, thermostability, pH effects, K(m) for different glucan primers and the glucosyl unit donor ADPGlc, V(max) using various primers, and stimulation by citrate. These properties were compared to those of zSSI purified over 1600-fold from maize endosperm by a parallel procedure. The major differences between the two enzymes were that the SSII activity displayed higher K(m) values for ADPGlc, a distinct temperature range for maximal activity, and different relative activities toward specific exogenous substrates. The purified SSI and SSII activities both were shown to be capable of elongating maltooligosaccharide primers in vitro.

Enzyme Stability↗
PubMed1993

Hydroxyethyl starch does not improve pancreas preservation with HTK.

The effect of hydroxyethyl starch on pancreas preservation with cardioplegic histidine-tryptophan-ketoglutarate solution (HTK) was investigated. The study was performed using an in vitro reperfusion system of the porcine pancreas. During organ preservation pancreatic weight, arterial pressure, volume flow, and washout of amylase and lactate were quantified. Addition of hydroxyethyl starch did not affect arteriovenous volume flow or washout of amylase and lactate during protective perfusion after pancreas preparation. However, hydroxyethyl starch in HTK prevented an increase in pancreatic weight at the end of the protective perfusion (102.2 +/- 4.55% vs 127.8 +/- 4.62% in controls; p < 0.005) and after 24 h cold ischemia (72.9 +/- 3.91% vs. 83.5 +/- 3.49% in controls; p < 0.05). Hydroxyethyl starch did not affect postischemic organ quality assessed during reperfusion in a perfusion chamber by pancreatic vascular resistance, amylase and lactate release, insulin secretion, and oxygen consumption. We conclude that hydroxyethyl starch does not bring about any further improvement in immediate postischemic organ quality assessed in an in vitro reperfusion system.

Amylases↗
PubMed1995

Cell-type specific, coordinate expression of two ADP-glucose pyrophosphorylase genes in relation to starch biosynthesis during seed development of Vicia faba L.

Several cDNA clones encoding two different ADP-glucose pyrophosphorylase (AGPase, EC 2.7.7.27) polypeptides denoted VfAGPC and VfAGPP were isolated from a cotyledonary library of Vicia faba L. Both sequences are closely related to AGPase small-subunit sequences from other plants. Whereas mRNA levels of VfAGPP were equally high in developing cotyledons and leaves, the mRNA of VfAGPC was present in considerable amounts only in cotyledons. During development of cotyledons, both mRNAs accumulated until the beginning of the desiccation phase and disappeared afterwards. The increase of AGPase activity in cotyledons during the phase of storage-product synthesis was closely followed by the accumulation of starch. The AGPase activity in crude extracts of cotyledons was insensitive to 3-phosphoglycerate whereas the activity from leaves could be activated more than five-fold. Inorganic phosphate inhibited the enzyme from both tissues but was slightly more effective on the leaf enzyme. There was a correlation at the cellular level between the distribution of VfAGPP and VfAGPC mRNAs and the accumulation of starch, as studied by in-situ hybridisation and by histochemical staining in parallel tissue sections of developing seeds, respectively. During the early phase of seed development (12-15 days after fertilization) VfAGPase mRNA and accumulation of starch were detected transiently in the hypodermal, chlorenchymal and outer parenchymal cell layers of the seed coat but not in the embryo. At 25 days after fertilization both synthesis of VfAGPase mR-NA and biosynthesis of starch had started in parenchyma cells of the inner adaxial zone of the cotyledons. During later stages, the expression of VfAGPase and synthesis of starch extended over most of the cotyledons but were absent from peripheral cells of the abaxial zone, provascular and procalyptral cells.

Amino Acid Sequence↗
PubMed1991

Sequence of the structural gene for granule-bound starch synthase of potato (Solanum tuberosum L.) and evidence for a single point deletion in the amf allele.

The genomic sequence of the potato gene for starch granule-bound starch synthase (GBSS; "waxy protein") has been determined for the wild-type allele of a monoploid genotype from which an amylose-free (amf) mutant was derived, and for the mutant part of the amf allele. Comparison of the wild-type sequence with a cDNA sequence from the literature and a newly isolated cDNA revealed the presence of 13 introns, the first of which is located in the untranslated leader. The promoter contains a G-box-like sequence. The deduced amino acid sequence of the precursor of GBSS shows a high degree of identity with monocot waxy protein sequences in the region corresponding to the mature form of the enzyme. The transit peptide of 77 amino acids, required for routing of the precursor to the plastids, shows much less identity with the transit peptides of the other waxy preproteins, but resembles the hydropathic distributions of these peptides. Alignment of the amino acid sequences of the four mature starch synthases with the Escherichia coli glgA gene product revealed the presence of at least three conserved boxes; there is no homology with previously proposed starch-binding domains of other enzymes involved in starch metabolism. We report the use of chimeric constructs with wild-type and amf sequences to localize, via complementation experiments, the region of the amf allele in which the mutation resides. Direct sequencing of polymerase chain reaction products confirmed that the amf mutation is a deletion of a single AT basepair in the region coding for the transit peptide.(ABSTRACT TRUNCATED AT 250 WORDS)

Alleles↗
PubMed1984

Dietary fibre in bread and corresponding flours--formation of resistant starch during baking.

Dietary fibre, assayed with an enzymatic/gravimetric method, was higher in wheat/rye bread than in the corresponding flours. The increase was most pronounced in crumbs from bread baked with mainly low-extraction-rate flour, and could be accounted for to a large extent as "resistant starch", i.e. a starch fraction available to amyloglucosidase only after solubilization with 2 m-KOH. The resistant starch was formed at dough-making and/or baking and did not increase further during freezing or storage at room temperature. The chemical modifications leading to resistant starch formation remain to be investigated. Starch-lipid complexes are probably not involved, since these are hydrolyzed by the heat-stable amylase used in the dietary fibre assay.

Bread↗
PubMed1992

Effects of acarbose on starch hydrolysis. Study in healthy subjects, ileostomy patients, and in vitro.

The effect of acarbose on hydrolysis of a pure starch meal was investigated in normal subjects and ileostomy patients by means of 13CO2 breath tests and blood glucose levels as parameters of absorption, and of H2 breath tests, serum acetate levels, and ileal loss of carbohydrate as parameters of malabsorption. Additional information on the effect of acarbose on alpha-amylase activity was obtained by in vitro experiments. Acarbose (200 and 400 mg) significantly delayed starch absorption. Serum acetate was found to be a less sensitive marker of malabsorption than breath H2 excretion. After intake of 50 g starch plus 400 mg acarbose, 23-71% of the starch load was lost in the ileostomy effluent, for a large part as starch. This suggests that acarbose considerably inhibits alpha-amylase, and not only brush-border enzymes. In vitro experiments confirm that an inhibition of two thirds of alpha-amylase activity can be expected from pharmacologically used doses of acarbose.

Acarbose↗
PubMed1982

[The elimination of hydroxyethyl starch 200/0.5, dextran 40 and oxypolygelatine (author's transl)].

After withdrawal of 400 ml whole blood and subsequent infusion of 500 ml of a colloidal plasma substituent, the intravascular and renal colloid elimination was investigated in 40 test subjects. The individual colloidal solutions could no longer be demonstrated in the intravascular space after the following times: 10% hydroxyethyl starch 200/0.5 (anthrone method) after six weeks, 10% dextran 40 (anthrone method) after two weeks, 6% hydroxyethyl starch 200/0.5 (anthrone method) after four weeks and 5.5% oxypolygelatine (hydroxyproline method) after two days. Colloidal plasma substitutes are polydisperse solutions with various molecular weights and degree of hydroxyethylation and therefore, also have a large number of different elimination constants. With repeated application, the intravascular colloid concentration shifts in favour of the molecules with a longer half life which are difficult to eliminate. The elimination of the clinically employed dextran 40 and oxypolygelatine solution could be best described with an open two-compartment model. As a result of its greater heterogeneity, the elimination of the moderately high molecular weight hydroxyethyl starch 200/0.5 could only be characterized approximately even assuming three elimination constants. In the first four days, the hydroxyethyl starch 200/0.5 was more rapidly eliminated compared to dextran 40. However, subsequently a very much lower elimination from the intravascular space was found for about 3% of the administered hydroxyethyl starch 200/0.5. Oxypolygelatine was eliminated especially rapidly. Accordingly, the greatest renal clearance was found for oxypolygelatine, which showed a close relation to the molecular weight. On the other hand, a rapid elimination simultaneously is followed by a correspondingly lower volume effect.

Adult↗
PubMed1995

Antilithiasic and hypocholesterolemic effects of diets containing autoclaved amylomaize starch in hamster.

The prevention of cholelithiasis by dietary manipulation was investigated in hamsters receiving a fat-free lithogenic (L) diet or this diet in which sucrose was replaced by 12 (group AS12), 36 (group AS36), 48 (group AS48), or 72.5% (group AS72.5) of autoclaved amylomaize starch for seven weeks. All hamsters (6/6) had cholesterol gallstones in groups L and AS12, while only 3/6 hamsters in group AS36 had gallstones. None were present in groups AS48 and AS72.5. Except in group AS12, biliary cholesterol level and lithogenic index (LI) decreased significantly in hamsters receiving amylomaize starch. Plasma cholesterol concentration was reduced by 31 and 54%, respectively, in groups AS48 and AS72.5 as compared to group L. The concentration of esterified cholesterol in the liver was also reduced significantly in all groups receiving amylomaize starch. Hepatic cholesterogenesis was decreased by 74 and 65%, respectively, in groups AS48 and AS72.5 as compared to group L. The transformation of cholesterol to bile acids was increased in group AS72.5 (+152%) as compared to L, while fecal cholesterol excretion was strongly lowered (-31%). Amylomaize starch reduced the microbial transformation of cholesterol to coprosterol and epicoprosterol, and in group AS72.5 it decreased the degradation of cholic acid. Thus, this autoclaved amylomaize starch, which could be used in human nutrition, prevents cholelithiasis and lowers cholesterolemia.

Animals↗
PubMed1998

Biochemical characteristics and fermentation of glucose and starch by rabbit caecal strains of Bifidobacterium globosum.

Two strains of Bifidobacterium globosum were isolated from caecal contents of rabbits in a search for potential probiotics. Both strains fermented glucose, galactose, pentoses, maltose, raffinose and starch. Common coccidiostats (monensin, salinomycin) and antimicrobial growth promotors (avoparcin, bacitracin, nitrovin, virginiamycin) supplied at 10 mg/L inhibited their growth in cultures with glucose. Fermentation parameters of bifidobacteria on glucose and starch differed. More formate and ethanol and less lactate were produced during growth on glucose than during growth on starch. When growing on starch, the two strains of bifidobacteria produced 1 mol lactate per 5.6 and 5.7 mol acetate, respectively. Corresponding values during growth on glucose were 17.3 and 8.4 mol of acetate per mol of lactate. Starch-grown cells accumulated more saccharides than cells grown on glucose (1.48 vs. 0.41 and 3.12 vs. 1.18 mmol glucose units per 1 g of dry matter, respectively).

Animals↗
PubMed1998

Kojic acid production by Aspergillus flavus using gelatinized and hydrolyzed sago starch as carbon sources.

Direct conversion of gelatinized sago starch into kojic acid by Aspergillus flavus strain having amylolytic enzymes was carried out at two different scales of submerged batch fermentation in a 250-mL shake flask and in a 50-L stirred-tank fermentor. For comparison, fermentations were also carried out using glucose and glucose hydrolyzate from enzymic hydrolysis of sago starch as carbon sources. During kojic acid fermentation of starch, starch was first hydrolyzed to glucose by the action of alpha-amylase and glucoamylase during active growth phase. The glucose remaining during the production phase (non-growing phase) was then converted to kojic acid. Kojic acid production (23.5 g/L) using 100 g/L sago starch in a shake flask was comparable to fermentation of glucose (31.5 g/L) and glucose hydrolyzate (27.9 g/L) but in the 50-L fermentor was greatly reduced due to non-optimal aeration conditions. Kojic acid production using glucose was higher in the 50-L fermentor than in the shake flask.

Aspergillus flavus↗
PubMed2003

Prior short-term consumption of resistant starch enhances postprandial insulin sensitivity in healthy subjects.

AIMS/HYPOTHESIS: Diets rich in insoluble-fibre are linked to a reduced risk of both diabetes and cardiovascular disease; however, the mechanism of action remains unclear. The aim of this study was to assess whether acute changes in the insoluble-fibre (resistant starch) content of the diet would have effects on postprandial carbohydrate and lipid handling. METHODS: Ten healthy subjects consumed two identical, low-residue diets on separate occasions for 24 h (33% fat; <2 g dietary fibre). Of the diets one was supplemented with 60 g resistant starch (Novelose 260). On the following morning a fibre-free meal tolerance test (MTT) was carried out (59 g carbohydrate; 21 g fat; 2.1 kJ) and postprandial insulin sensitivity (SI(ORAL)) assessed using a minimal model approach. RESULTS: Prior resistant starch consumption led to lower postprandial plasma glucose (p=0.037) and insulin (p=0.038) with a higher insulin sensitivity(44+/-7.5 vs 26+/-3.5 x 10(-4) dl kg(-1) min(-1) per micro Uml(-1); p=0.028) and C-peptide-to-insulin molar ratio (18.7+/-6.5 vs 9.7+/-0.69; p=0.017). There was no effect of resistant starch consumption on plasma triacylglycerol although non-esterified fatty acid and 3-hydroxybutyrate levels were suppressed 5 h after the meal tolerance test. CONCLUSION: Prior acute consumption of a high-dose of resistant starch enhanced carbohydrate handling in the postprandial period the following day potentially due to the increased rate of colonic fermentation.

Adult↗
PubMed2007

Production of L-Lysine from starch by Corynebacterium glutamicum displaying alpha-amylase on its cell surface.

We engineered a Corynebacterium glutamicum strain displaying alpha-amylase from Streptococcus bovis 148 (AmyA) on its cell surface to produce amino acids directly from starch. We used PgsA from Bacillus subtilis as an anchor protein, and the N-terminus of alpha-amylase was fused to the PgsA. The genes of the fusion protein were integrated into the homoserine dehydrogenase gene locus on the chromosome by homologous recombination. L-Lysine fermentation was carried out using C. glutamicum displaying AmyA in the growth medium containing 50 g/l soluble starch as the sole carbon source. We performed L-lysine fermentation at various temperatures (30-40 degrees C) and pHs (6.0-7.0), as the optimal temperatures and pHs of AmyA and C. glutamicum differ significantly. The highest L-lysine yield was recorded at 30 degrees C and pH 7.0. The amount of soluble starch was reduced to 18.29 g/l, and 6.04 g/l L-lysine was produced in 24 h. The L-lysine yield obtained using soluble starch as the sole carbon source was higher than that using glucose as the sole carbon source after 24 h when the same amount of substrates was added. The results shown in the current study demonstrate that C. glutamicum displaying alpha-amylase has a potential to directly convert soluble starch to amino acids.

Bacterial Proteins↗
PubMed2006

Digestibility of resistant starch containing preparations using two in vitro models.

BACKGROUND: Resistant starch (RS) is known for potential health benefits in the human colon. To investigate these positive effects it is important to be able to predict the amount, and the structure of starch reaching the large intestine. AIM OF THE STUDY: The aim of this study was to compare two different in vitro models simulating the digestibility of two RS containing preparations. METHODS: The substrates, high amylose maize (HAM) containing RS type 2, and retrograded long chain tapioca maltodextrins (RTmd) containing RS type 3 were in vitro digested using a batch and a dynamic model, respectively. Both preparations were characterized before and after digestion by using X-Ray and DSC, and by measuring their total starch, RS and protein contents. RESULTS: Using both digestion models, 60-61 g/100 g of RTmd turned out to be indigestible, which is very well in accordance with 59 g/100 g found in vivo after feeding RTmd to ileostomy patients. In contrast, dynamic and batch in vitro digestion experiments using HAM as a substrate led to 58 g/100 g and 66 g/100 g RS recovery. The degradability of HAM is more affected by differences in experimental parameters compared to RTmd. The main variations between the two in vitro digestion methods are the enzyme preparations used, incubation times and mechanical stress exerted on the substrate. However, for both preparations dynamically digested fractions led to lower amounts of analytically RS and a lower crystallinity. CONCLUSIONS: The two in vitro digestion methods used attacked the starch molecules differently, which influenced starch digestibility of HAM but not of RTmd.

Amylose↗
PubMed2001

The contribution of plastidial phosphoglucomutase to the control of starch synthesis within the potato tuber.

The aim of this work was to evaluate the extent to which plastidial phosphoglucomutase (PGM) activity controls starch synthesis within potato (Solanum tuberosum L. cv. Desirée) tubers. The reduction in the activity of plastidial PGM led to both a correlative reduction in starch accumulation and an increased sucrose accumulation. The control coefficient of plastidial PGM on the accumulation of starch was estimated to approximate 0.24. The fluxes of carbohydrate metabolism were measured by investigating the metabolism of [U-14C]glucose in tuber discs from wild-type and transgenic plants. In tuber discs the control coefficient of plastidial PGM over starch synthesis was estimated as 0.36, indicating that this enzyme exerts considerable control over starch synthesis within the potato tuber.

Amino Acids↗
PubMed2004

Starch properties of the sago palm (Metroxylon sagu Rottb.) in different soils.

We investigated the relationships between starch concentrations and activities of starch synthetic enzymes in sago palms (Metroxylon sagu Rottb.) under acid sulfate and mineral soil conditions. Plants grown naturally that had reached their maturated stage were sampled. We found that the growth in acid sulfate soil is lower than that in mineral soil and that starch granules were larger and there was more amylase activity in acid sulfate soil than in mineral soil. Lower amylase activity in mineral soil could eliminate the degradation of starch, making the smaller granules suitable for storing large amounts of starch in a limited space inside cells.

Amino Acid Sequence↗
PubMed1986

Effects of dietary sucrose levels on pH fall and acid-anion profile in human dental plaque after a starch mouth-rinse.

The effects on the metabolism of starch by plaques formed in human subjects during periods of dietary sucrose limitation or supplementation were studied. High sucrose (HS) plaques showed lower resting pH and pH minima, and higher concentrations of lactate ion after the starch mouth-rinse than low sucrose (LS) plaques. Plaque samples incubated with starch solutions in vitro showed no differences in final pH or acid-anion concentrations between HS and LS diets. Plaque-amylase activity was higher on HS than LS diets. Thus starch was more acidogenic when consumed as part of a diet already rich in sucrose, but it is unclear whether this was a specific or non-specific effect of starch on plaque metabolism.

Adult↗