Microscopy of starch: evidence of a new level of granule organization

Gallant, Daniel J.; Bouchet, Brigitte; Baldwin, Paul M.

doi:10.1016/s0144-8617(97)00008-8

Cited by 912 publications

(615 citation statements)

References 38 publications

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“…X-ray photoelectron spectroscopic (XPS) data (SI Materials and Methods) provide conclusive experimental evidence for the presence of starch molecules within the AuNP-BBN framework. Detailed structural investigations of starch molecules reveal a combination of both lamellar and fibrous networks, which are composed of spherical blocklets 400-500 nm in diameter (22,23). The average size of a bombesin peptide used in the present study is around 2-3 nm.…”

Section: Resultsmentioning

confidence: 99%

Bombesin functionalized gold nanoparticles show in vitro and in vivo cancer receptor specificity

Chanda¹,

Kattumuri²,

Shukla³

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

293

245

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Development of cancer receptor-specific gold nanoparticles will allow efficient targeting/optimum retention of engineered gold nanoparticles within tumors and thus provide synergistic advantages in oncology as it relates to molecular imaging and therapy. Bombesin (BBN) peptides have demonstrated high affinity toward gastrin-releasing peptide (GRP) receptors in vivo that are overexpressed in prostate, breast, and small-cell lung carcinoma. We have synthesized a library of GRP receptor-avid nanoplatforms by conjugating gold nanoparticles (AuNPs) with BBN peptides. Cellular interactions and binding affinities (IC 50 ) of AuNP-BBN conjugates toward GRP receptors on human prostate cancer cells have been investigated in detail. In vivo studies using AuNP-BBN and its radiolabeled surrogate 198 AuNP-BBN, exhibiting high binding affinity (IC 50 in microgram ranges), provide unequivocal evidence that AuNP-BBN constructs are GRP-receptor-specific showing accumulation with high selectivity in GRP-receptor-rich pancreatic acne in normal mice and also in tumors in prostate-tumor-bearing, severe combined immunodeficient mice. The i.p. mode of delivery has been found to be efficient as AuNP-BBN conjugates showed reduced RES organ uptake with concomitant increase in uptake at tumor targets. The selective uptake of this new generation of GRP-receptor-specific AuNP-BBN peptide analogs has demonstrated realistic clinical potential in molecular imaging via x-ray computed tomography techniques as the contrast numbers in prostate tumor sites are severalfold higher as compared to the pretreatment group (Hounsfield unit = 150).gold nanoparticles | bombesin | gastrin-releasing peptide receptor | prostate cancer | computed tomography imaging

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Section: Resultsmentioning

confidence: 99%

Bombesin functionalized gold nanoparticles show in vitro and in vivo cancer receptor specificity

Chanda¹,

Kattumuri²,

Shukla³

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

293

245

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“…This effect was greater in maize starch, indicating structural differences in both starches [34]. Gallant et al [35] found a correlation between BD viscosity and starch structures. Their results show that starches, which display less BD viscosity, consist of amylopectin with more branch chains of DP !…”

Section: Pasting Characteristicsmentioning

confidence: 93%

Acetylation of banana (Musa paradisiaca L.) and maize (Zea mays L.) starches using a microwave heating procedure and iodine as catalyst: Partial characterization

Sánchez‐Rivera¹,

Flores-Ramírez²,

Zamudio‐Flores³

et al. 2010

Starch Stärke

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Banana and maize starches were acetylated with acetic anhydride in the presence of different levels of catalytic agent (iodine) using microwave heating. Degree substitution, he Fourier transforms infrared (FT-IR) spectra, the morphological properties, the gelatinization and retrogradation characteristics, the pasting property and X-ray diffraction pattern were evaluated. The FT-IR study showed that acetylation was produced in both starches, a strong absorption band at 1740 cm À1 , and this signal rose when the concentration of iodine increased; this pattern was corroborated with degree substitution of both starches. SEM revealed more exo-corrosion and fusion in acetylated maize starch granules. Acetylated banana starch had higher crystallinity level than maize starch, and the crystallinity level decreased when the catalyst concentration increased. Similar pattern was show for the average temperature and enthalpy of gelatinization. In general, the acetylation retards the starch retrogradation, but at longer storage time this effect was minimized. Difference in the retrogradation level was found between both starches. Using microwave heating and different iodine concentrations as catalyst is possible produce acetylation of starch with specific physicochemical characteristics.

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“…The latter is a branched a-1,4:a-1,6 D-glucan and accounts for 70-90% of the starch dry weight. Amylose, to the granule surface (Gallant et al, 1997). Due to clustering of the branching points and the length distribution of the side chains within a single amylopectin molecule, neighboring chains are capable of double-helix formation (Smith, 2001).…”

Section: Introductionmentioning

confidence: 99%

“…The A-type allomorph, which is typical of wild-type cereal starches, is more compact and contains fewer water molecules between the double helices compared to the B-type structure. The latter is found in storage organs, such as potato tubers, and also in some high-amylose cereal starches (Gallant et al, 1997;Gé rard et al, 2001). Legume starches are considered to represent a third allomorph (C-type), as both A-and B-type crystallites are found within the same starch particle (Bogracheva et al, 2001;Imberty et al, 1991).…”

Section: Introductionmentioning

confidence: 99%

Glucan, water dikinase phosphorylates crystalline maltodextrins and thereby initiates solubilization

Hejazi¹,

et al. 2008

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SummaryStarch phosphorylation by glucan, water dikinase (GWD; EC 2.7.9.4) is an essential step in the breakdown of native starch particles, but the underlying mechanisms have remained obscure. In this paper, the initial reactions of starch degradation were analyzed using crystallized maltodextrins as model carbohydrates. As revealed by X-ray diffraction analysis, the crystallized maltodextrins represent the B-type starch allomorph. Recombinant GWD phosphorylated crystalline maltodextrins with a high specific activity (55-60 nmol mg )1 protein min )1 ), but exhibited very little activity with the same maltodextrins that had been solubilized by heat treatment. Recombinant phosphoglucan, water dikinase (PWD; EC 2.7.9.5) utilized the crystalline maltodextrins only when pre-phosphorylated by GWD. Phosphorylation of crystalline maltodextrins, as catalyzed by GWD, initiated solubilization of neutral as well as phosphorylated glucans. In both the insoluble and the soluble state, mono-, di-and triphosphorylated a-glucans were observed, with wide and overlapping ranges of degree of polymerization. Thus, the substrate specificity of the GWD is defined by the physical arrangement of a-glucans rather than by structural parameters, such as the distribution of branching points or degree of polymerization. Unlike GWD and PWD, recombinant b-amylase isozyme 3 (BAM3), which has been shown to be essential for plastidial starch degradation, preferentially degraded soluble maltodextrins rather than crystallized glucans. In summary, two conclusions were reached. Firstly, carbohydrate targets of GWD are primarily defined by the molecular order of glucan helices. Secondly, GWD-catalyzed phosphorylation mediates the phase transition of glucans from a highly ordered to a less ordered and hydrated state.

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Microscopy of starch: evidence of a new level of granule organization

Cited by 912 publications

References 38 publications

Bombesin functionalized gold nanoparticles show in vitro and in vivo cancer receptor specificity

Bombesin functionalized gold nanoparticles show in vitro and in vivo cancer receptor specificity

Acetylation of banana (Musa paradisiaca L.) and maize (Zea mays L.) starches using a microwave heating procedure and iodine as catalyst: Partial characterization

Glucan, water dikinase phosphorylates crystalline maltodextrins and thereby initiates solubilization

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