Neutral Chains Research Articles

Electromechanical coupling of the Kv1.1 voltage-gated K+ channel is fine-tuned by the simplest amino acid residue in the S4-S5 linker.

Investigating the Shaker-related K+ channel Kv1.1, the dysfunction of which is responsible for episodic ataxia 1 (EA1), at the functional and molecular level provides valuable understandings on normal channel dynamics, structural correlates underlying voltage-gating, and disease-causing mechanisms. Most studies focused on apparently functional amino acid residues composing voltage-gated K+ channels, neglecting the simplest ones. Glycine at position 311 of Kv1.1 is highly conserved both evolutionarily and within the Kv channel superfamily, is located in a region functionally relevant (the S4-S5 linker), and results in overt disease when mutated (p.G311D). By mutating the G311 residue to aspartate, we show here that the channel voltage-gating, activation, deactivation, inactivation, and window currents are markedly affected. In silico, modeling shows this glycine residue is strategically placed at one end of the linker helix which must be free to both bend and move past other portions of the protein during the channel's opening and closing. This is befitting of a glycine residue as its small neutral side chain allows for movement unhindered by interaction with any other amino acid. Results presented reveal the crucial importance of a distinct glycine residue, within the S4-S5 linker, in the voltage-dependent electromechanical coupling that control channel gating.

Physicochemical properties and proximate composition of tamarillo (Solanum betaceum Cav.) fruits from New Zealand

This study reports physical parameters, proximate compositions, reducing sugar and amino acid contents in Amber, Laird’s Large and Mulligan tamarillos that were produced in New Zealand. Across all three cultivars, about 3 % of dietary fibre was present. Higher amounts of neutral side chains were observed in pectin from Laird’s Large compared to other cultivars and in pectin from pulps compared to peels. Among 22 detected amino acids, 2 essential amino acids and 5 non-essential amino acids were reported herein for the first time. The total amino acids content in peel and pulp of tamarillos ranged from 1192 to 1753 and 3455–6077 mg 100 g−1 dry weight, respectively. l-glutamic acid, γ-aminobutyric acid and l-aspartic acid dominated amino acid profile of tamarillo except for Amber peel. l-histidine and l-lysine dominated the essential amino acid profile of all tamarillo samples. Principal component analysis revealed a clear separation among soluble sugar and amino acid profiles of different cultivars and tissues of tamarillo.

Okra polysaccharides/gelatin complex coacervate as pH-responsive and intestine-targeting delivery protects isoquercitin bioactivity

Okra polysaccharides (OPs) belong to RG I pectin branched with neutral saccharide side chains, which possesses distinctive structure and physicochemical properties from the commonly used HG pectin. Until now, the application of RG I pectin as wall material of microcapsule remains unclear. Here, we obtained OPs/gelatin complex coacervate at the maximum yield of 86.8% (pH 3.5, gelatin/OPs ratio 9:1 and 2% (w/v) total polymer concentration) by response surface methodology. Isoquercitin (IQ)-loaded OPs/gelatin complex coacervate (OGIQ) showed porous spongy-like surface structure with average particle size, encapsulation efficiency and surface porosity at 334 nm, 81.6% and 31.9%, respectively. OGIQ was found to be pH-responsive and intestine-targeting. The IQ-release rate of OGIQ was assayed to be 89.4% in intestine fluid and below 2% in acidic and simulated gastric digestion, respectively. Accordingly, embedding in OGIQ protected IQ in digestion and improved its postdigestive α-glucosidase inhibitory rate by 88.7%. The differential scanning calorimetry curves showed that OGIQ effectively prevented IQ from thermal decomposition. The XRD, FT-IR and CD spectra indicated that IQ was embedded in OGIQ in amorphous state by hydrogen bonds and electrostatic interaction. Compared with HG, the neutral saccharide side chains of OPs could induce different secondary conformation change of gelatin during complex coacervation.

Molybdenum(III) Thiocyanate- and Selenocyanate-Based One-Dimensional Heteronuclear Polymers: Coordination Affinity-Controlled Assemblage of Mixed Spin and Mixed Valence Derivatives with Ni(II) and Co(II/III).

One-dimensional coordination polymers constructed with the 4d metallo-ligand [Mo(NCS)6]3- associated with NiII and CoII complexes are reported. The first series consists of anionic NCS-bridged [Mo-MII]- coordination polymers associated with a discrete paramagnetic complex or a diamagnetic CoIII complex acting as cations. The latter takes advantage of the coordination preference of the S-ligand for the soft 3d ions and has led to hetero-trimetallic [MoIIINiIICoIII] and mixed valence [MoIIICoIICoIII] compounds. A second series concerns neutral chains in which trinuclear [Mo M2II] units are bridged by an additional NCS anion. The soft character of the S atom was also the key to a rare example of a compound involving both high-spin and low-spin CoII centers associated with [Mo(NCS)6]. A [Mo-Ni] derivative obtained with [Mo(NCSe)6]3- has been considered in order to evaluate the effect of Se versus S on the exchange interaction. The spin distribution for selenocyanate metallo-ligand has been assessed by density functional theory calculations. The crystal structures for all compounds have been characterized, and their magnetic behaviors have been investigated. These ferrimagnetic systems are characterized by antiferromagnetic Mo-MII interactions in the range of -40 to -90 cm-1 (based on H = -JSaSb formalism) operative both with CoII and with NiII, thus demonstrating the potential of the MoIII-NCS combination for molecular systems in which exchange interactions play an important role.

Interaction of the neutral amino acid transporter ASCT2 with basic amino acids.

Glutamine transport across cell membranes is performed by a variety of transporters, including the alanine serine cysteine transporter 2 (ASCT2). The substrate-binding site of ASCT2 was proposed to be specific for small amino acids with neutral side chains, excluding basic substrates such as lysine. A series of competitive inhibitors of ASCT2 with low µM affinity were developed previously, on the basis of the 2,4-diaminobutyric acid (DAB) scaffold with a potential positive charge in the side chain. Therefore, we tested whether basic amino acids with side chains shorter than lysine can interact with the ASCT2 binding site. Molecular docking of L-1,3-diaminopropionic acid (L-DAP) and L-DAB suggested that these compounds bind to ASCT2. Consistent with this prediction, L-DAP and L-DAB, but not ornithine, lysine or D-DAP, elicited currents when applied to ASCT2-expressing cells. The currents were carried by anions and showed the hallmark properties of ASCT2 currents induced by transported substrates. The L-DAP response could be eliminated by a competitive ASCT2 inhibitor, suggesting that binding occurs at the substrate binding site. The KM for L-DAP was weakly voltage dependent. Furthermore, the pH dependence of the L-DAP response showed that the compound can bind in several protonation states. Together, these results suggest that the ASCT2 binding site is able to recognize L-amino acids with short, basic side chains, such as the L-DAP derivative β-N-methylamino-l-Alanine (BMAA), a well-studied neurotoxin. Our results expand the substrate specificity of ASCT2 to include amino acid substrates with positively charged side chains.

Pectic galactan affects cell wall architecture during secondary cell wall deposition.

β-(1,4)-galactan determines the interactions between different matrix polysaccharides and cellulose during the cessation of cell elongation. Despite recent advances regarding the role of pectic β-(1,4)-galactan neutral side chains in primary cell wall remodelling during growth and cell elongation, little is known about the specific function of this polymer in other developmental processes. We have used transgenic Arabidopsis plants overproducing chickpea βI-Gal β-galactosidase under the 35S CaMV promoter (35S::βI-Gal) with reduced galactan levels in the basal non-elongating floral stem internodes to gain insight into the role of β-(1,4)-galactan in cell wall architecture during the cessation of elongation and the beginning of secondary growth. The loss of galactan mediated by βI-Gal in 35S::βI-Gal plants is accompanied by a reduction in the levels of KOH-extracted xyloglucan and an increase in the levels of xyloglucan released by a cellulose-specific endoglucanase. These variations in cellulose-xyloglucan interactions cause an altered xylan and mannan deposition in the cell wall that in turn results in a deficient lignin deposition. Considering these results, we can state that β-(1,4)-galactan plays a key structural role in the correct organization of the different domains of the cell wall during the cessation of growth and the early events of secondary cell wall development. These findings reinforce the notion that there is a mutual dependence between the different polysaccharides and lignin polymers to form an organized and functional cell wall.

Discovery and Pharmacokinetics of Sulfamides and Guanidines as Potent Human Arginase 1 Inhibitors.

We designed and synthesized a series of arginase inhibitors as derivatives of the well-known 2-(S)-amino-6-boronohexanoic acid (ABH) with basic and neutral side chains in the α-position relative to the amino acid group. In an effort to improve the pharmacokinetic profile of literature examples and retain potent enzymatic activity, sulfamido moieties were introduced to generate hydrogen bond interaction with the aspartic acid residue in the arginase active site. The compounds with basic guanidine-containing side chains were even more potent arginase inhibitors. Both groups of compounds, as designed, demonstrated low clearance in their pharmacokinetic profile. The most active inhibitor 15aa showed high nanomolar potency with IC50 = 32 nM toward human arginase 1 and demonstrated low clearance (4.2 mL/min/kg), long t 1/2, and moderate volume of distribution in rat pharmacokinetic studies.

Profiling C4N radicals of astrophysical interest

ABSTRACT Based on a theoretical study of neutral, anion, and cation $\text{C}_{4}\text{N}$ chains, we suggest that this molecular species can still be observed in space. We analyse the dependence on n of the enthalpies of formation across the $\text{C}_{{{ n}}}\text{N}$ family and present possible chemical pathways of $\text{C}_{4}\text{N}$ production, which are not only exoenergetic but also barrierless. To further assist astronomical observation, we report estimates obtained at the CCSD(T) level of theory for astrophysically and astrochemically relevant properties. These include structural and chemical data, dipole moments, vibrational frequencies, rotational and centrifugal distortion constants as well as electron affinity, ionization potential, and related chemical reactivity indices. Our results indicate that anion chains can be easily detected in space than neutral chains; $\text{C}_{4}\text{N}^{-}$ possesses a smaller enthalpy of formation and a substantially larger dipole moment than $\text{C}_{4}\text{N}^{\text{0}}$.

Extensive Quantum Chemistry Study of Neutral and Charged C4N Chains: An Attempt To Aid Astronomical Observations

Many molecular species can presumably still be observed in space if they are adequately characterized chemically. In this paper, we suggest that this could be the case of the neutral (C$_4$N$^0$) and anion (C$_4$N$^-$) cyanopropynylidene chains, which were not yet identified in space although both the neutral (C$_3$N$^0$ and C$_5$N$^0$) and anion (C$_3$N$^-$} and C$_5$N$^-$) neighboring members of the homologous series were observed. Extensive data obtained from quantum chemical calculations using density functional theory (DFT), coupled cluster (CC), and quadratic configuration interaction (QCI) methods for all charge and spin states of interest for space science (doublet and quartet neutrals, triplet and singlet anions, and singlet and triplet cations) are reported: e.g., bond metric and natural bond order data, enthalpies of formation, dissociation and reaction energies, spin gaps, rotational constants, vibrational properties, dipole and quadrupole momenta, electron attachment energies ($EA$) and ionization potentials ($IP$). The fact that (not only for C$_4$N but also for C$_2$N and C$_6$N) the quantum chemical methods utilized here are able to excellently reproduce the experimental $EA$ value -- which is often a challenge for theory -- is particularly encouraging, since this indicates that theoretical estimates of chemical reactivity indices (which are key input parameters for modeling astrochemical evolution) can be trusted. The presently calculated enthalpies of formation and dissociation energies do not substantiate any reason to assume that C$_4$N is absent in space. To further support this idea, we analyze potential chemical pathways of formation of both C$_4$N$^0$ and C$_4$N$^-$, which include association and exchange reactions.

Self-assembly of square planar rhodium carbonyl complexes with 4,4-disubstituted-2,2′-bipyridine ligands

The impact of non-covalent interactions and reaction conditions on formation and self-assembly of ionic pairs of Rh complexes with 4,4′-disubstituted bipyridine ligands ([Rh(L1)(CO)2][Rh(CO)2Cl2])n(1), [Rh(L1)2Cl2][Rh(CO)2Cl2] (2), ([Rh(L1)(CO)2][Rh(CO)2Cl2][Rh(L1)(CO)2]n([Rh(CO)2(Cl)2])n) (3), ([Rh(L2)CO2] [Rh(CO)2Cl2])n·EtOH (4), ([Rh(L2)(CO)2])n ([Rh(CO)2Cl2])n(5) (L1 = 4,4′-dimethyl-2,2′-bipyridine, L2 = 4,4′-diamine-2,2′-bipyridine) have been studied. Packing of square planar Rh complexes favor formation of one-dimensional chains. In structure 1, the polymeric chain is formed by the alternating cationic [Rh(L1)(CO)2]+ and the anionic [Rh(CO)2Cl2]- units leading to a neutral pseudo linear 1D chain with metallophilic contacts. In compound 2, the square planar [Rh(CO)2Cl2]- anions form only dinuclear anion pairs instead of polymeric chains. Structure 3 consists of an alternative arrangement of cations and anions compared to 1, the repeating sequence of ions being [Rh(L1)(CO)2]+[Rh(CO)2Cl2]-[Rh(L1)(CO)2]+. The overall positive charge is balanced by outlying [Rh(CO)2Cl2]- counterion. In structures 4 and 5, only the cationic [Rh(L2)(CO)2]+ units are involved in formation of the polymeric chains and the positive charge of the chain is balanced by the [Rh(CO)2Cl2]- (4 and 5). In structures 1 and 3 the metallophilic interactions have an important role in chain formation. In 4 and 5, the arrangement of the square planar building blocks is dominated by the hydrogen bonding between the NH2-substituents of the bipyridine ligand and the chlorides of the anion or solvent of crystallization.

Dietary Fiber Pectin Ameliorates Experimental Colitis in a Neutral Sugar Side Chain-Dependent Manner.

Dietary fiber, with intake of soluble fibers in particular, has been reported to lower the risk for developing inflammatory bowel diseases (IBD). This is at least partly attributable to the fermentation of dietary fiber by the colonic microbiota to produce short chain fatty acids. Pectin, a widely consumed soluble fiber, is known to exert a protective effect in murine models of IBD, but the underlying mechanism remains elusive. Apart from having a prebiotic effect, it has been suggested that pectin direct influences host cells by modulating the inflammatory response in a manner dependent on its neutral sugar side chains. Here we examined the effect of the side chain content of pectin on the pathogenesis of experimental colitis in mice. Male C57BL/6 mice were fed a pectin-free diet, or a diet supplemented with characteristically high (5% orange pectin) or low (5% citrus pectin) side chain content for 10–14 days, and then administered 2,4,6-trinitrobenzene sulfonic acid or dextran sulfate sodium to induce colitis. We found that the clinical symptoms and tissue damage in the colon were ameliorated in mice that were pre-fed with orange pectin, but not in those pre-fed with citrus pectin. Although the population of CD4+Foxp+ regulatory T cells and CD4+RORγt+ inflammatory T cells in the colon were comparable between citrus and orange pectin-fed mice, colonic interleukin (IL)-1β and IL-6 levels in orange pectin-fed mice were significantly decreased. The fecal concentration of propionic acid in orange pectin-fed mice was slightly but significantly higher than that in control and citrus pectin-fed mice but the cecal concentration of propionic acid after the induction of TNBS colitis was comparable between orange and citrus pectin-fed mice. Furthermore, the protective effect of orange pectin against colitis was observed even in mice treated with antibiotics. IL-6 production from RAW264.7 cells stimulated with the toll-like receptor agonist Pam3CSK4 or lipopolysaccharide was suppressed by pre-treatment with orange pectin in vitro. Taken together, these results suggest that the side chains of pectin not only augment prebiotic effects but also directly regulate IL-6 production from intestinal host cells in a microbiota-independent fashion to attenuate colitis.

Determination of chemical structure of pea pectin by using pectinolytic enzymes

The chemical structure of pea pectin was delineated using pectin-degrading enzymes and biochemical methods. The molecular weight of the pea pectin preparation was 488,000, with 50 % arabinose content, and neutral sugar side chains attached to approximately 60 % of the rhamnose residues in rhamnogalacturonan-I (RG-I). Arabinan, an RG-I side chain, was highly branched, and the main chain was comprised of α-1,5-l-arabinan. Galactose and galactooligosaccharides were attached to approximately 35 % of the rhamnose residues in RG-I. Long chain β-1,4-galactan was also present. The xylose substitution rate in xylogalacturonan (XGA) was 63 %. The molar ratio of RG-I/homogalacturonan (HG)/XGA in the backbone of the pea pectin was approximately 3:3:4. When considering neutral sugar side chain content (arabinose, galactose, and xylose), the molar ratio of RG-I/HG/XGA regions in the pea pectin was 7:1:2. These data will help understand the properties of pea pectin.

Catalytic Hydrogenation of N‐protected α‐Amino Acids Using Ruthenium Complexes with Monodentate Phosphine Ligands

AbstractA ruthenium complex with a monodentate phosphine ligand was used to catalytically hydrogenate N‐protected α‐amino acids under essential retention of the configuration of their α‐chiral centers. Among the ligands tested for this hydrogenation, which proceeds at a relatively low temperature, tris(para‐fluorophenyl)phosphine exhibited the best performance. In comparison, electron‐rich monodentate, bidentate, and tridentate phosphines were far less effective. The precatalyst Ru(OAc)2[(p‐FC6H4)3P]2 was synthesized and isolated, and its structure was determined by a single‐crystal X‐ray diffraction analysis. N‐protected α‐amino acids with neutral alkyl side chains, including polar functional groups such as sulfides, indoles, ethers, phenols, pyrroles, and arenes, are compatible with the applied hydrogenation conditions, affording the corresponding optically active 2‐substituted‐2‐(1H‐pyrrol‐1‐yl)ethan‐1‐ol (2‐amino ethanol) derivatives in moderate to high yield.magnified image

A DFT study on radical-cationic methanol clusters: Structure, bonding and H-transfer

Radical-cationic methanol clusters (CH3OH) +n, n = 2–5, are studied in the gas phase and solvent methanol using hybrid B3LYP, CAM-B3LYP and BHandHLYP exchange-correlation functionals. The CAM-B3LYP predictions are the most consistent. Ionization of parental neutral rings and chains yields distonic radical cations with spin residing on the CH3O link. Higher energy OO hemibonded structures are also located. The intra-cluster H-transfer from the methyl group of the CH3OH-terminus of the protonated moiety to the O-atom of the CH3O terminus in chain radical cations leads to the lowest-energy distonic isomers with the CH2OH terminus. The CAM-B3LYP activation enthalpies for this reaction in the gas phase are 9.5, 11.1, 13.7, and 17.1 kcal/mol for n = 5, 4, 3, 2, respectively. The inter-cluster H-transfer from the CH3O terminus to a neutral methanol cluster occurs spontaneously, with formation of a protonated cluster weakly bound to the radical cluster. The protonated cluster may serve as a proton carrier.

Preliminary Structural Characteristic of Polysaccharides Extracted From the Callus Tissue of Sosnowskyi’s Hogweed (Heracleum Sosnowskyi Manden) Stem by Aqueous Ammonium Oxalate

Pectic polysaccharides have been isolated from callus tissue of the stem of Sosnowskyi’s hogweed (Heracleum sosnowskyi Manden) by extraction with a 0.7% aqueous solution of ammonium oxalate and characterized. It was shown that they differ from pectic polysaccharides of a native plant by a lower content of D‑galacturonic acid residues and a higher content of arabinose and galactose residues. The results obtained by a combination of ion exchange chromatography, enzymatic hydrolysis, periodate oxidation, methylation and NMR spectroscopy indicated the presence of low-methyl esterified 1,4-α-D-galacturonan, rhamogalacturonan-I, arabinan and galactan or arabinogalactan. The terminal 1,2- and 1,5-linked arabinofuranose residues, terminal, 1,3-, 1,6-linked and 3,6-substituted galactopyranose residues and 1,4-linked hexopyranose (galactopyranose or glucopyranose) residues were identified in the composition of neutral carbohydrate chains. The presence in the NMR spectra of trans-glycosyl correlation peaks of the methyl groups of 2,4-di-O-substituted rhamnose residues indirectly confirm the attachment arabinan, galactan or arabinogalactan carbohydrate chains to rhamnopyranose residues of the backbone at C-4 position.

Conformational Properties of Comb-shaped Polyelectrolytes with Negatively Charged Backbone and Neutral Side Chains Studied by a Generic Coarse-grained Bead-and-Spring Model

A generic coarse-grained bead-and-spring model, mapped onto comb-shaped polycarboxylate-based (PCE) superplasticizers, is developed and studied by Langevin molecular dynamics simulations with implicit solvent and explicit counterions. The agreement on the radius of gyration of the PCEs with experiments shows that our model can be useful in studying the equilibrium sizes of PCEs in solution. The effects of ionic strength, side-chain number, and side-chain length on the conformational behavior of PCEs in solution are explored. Single-chain equilibrium properties, including the radius of gyration, end-to-end distance and persistence length of the polymer backbone, shape-asphericity parameter, and the mean span dimension, are determined. It is found that with the increase of ionic strength, the equilibrium sizes of the polymers decrease only slightly, and a linear dependence of the persistence length of backbone on the Debye screening length is found, in good agreement with the theory developed by Dobrynin. Increasing side-chain numbers and/or side-chain lengths increases not only the equilibrium sizes (radius of gyration and mean span) of the polymer as a whole, but also the persistence length of the backbone due to excluded volume interactions.

Crystal structure of bisoprolol fumarate Form I, (C18H32NO4) (C4H2O4)0.5

The crystal structure of bisoprolol fumarate Form I has been solved and refined using synchrotron X-ray powder diffraction data and optimized using density functional techniques. Bisoprolol fumarate Form I crystallizes in space group P-1 (#2) with a = 8.165 70(5) Å, b = 8.516 39(12) Å, c = 16.751 79(18) Å, α = 89.142(1)°, β = 78.155(1)°, γ = 81.763(1)°, V = 1128.265(10) Å3, and Z = 2. The neutral side chain of the bisoprolol cation is probably disordered. The cation and anion are linked by N–H⋯O and O–H⋯O hydrogen bonds. The cations are also linked by N–H⋯O hydrogen bonds. The result is alternating layers of hydrophilic and hydrophobic layers parallel to the ab-plane. The density of the structure is relatively low at 1.130 g cm−3, but there are no obvious voids in the structure. The powder pattern is included in the Powder Diffraction File™ as entry 00-066-1625.

Towards understanding the doping mechanism of organic semiconductors by Lewis acids.

Precise doping of organic semiconductors allows control over the conductivity of these materials, an essential parameter in electronic applications. Although Lewis acids have recently shown promise as dopants for solution-processed polymers, their doping mechanism is not yet fully understood. In this study, we found that B(C6F5)3 is a superior dopant to the other Lewis acids investigated (BF3, BBr3 and AlCl3). Experiments indicate that Lewis acid-base adduct formation with polymers inhibits the doping process. Electron-nuclear double-resonance and nuclear magnetic resonance experiments, together with density functional theory, show that p-type doping occurs by generation of a water-Lewis acid complex with substantial Brønsted acidity, followed by protonation of the polymer backbone and electron transfer from a neutral chain segment to a positively charged, protonated one. This study provides insight into a potential path for protonic acid doping and shows how trace levels of water can transform Lewis acids into powerful Brønsted acids.

Tailoring polycarboxylate architecture to improve the rheological properties of cement paste

This study elucidates the link between polycarboxylate (PC) architecture (random vs. block) and rheological properties of cement pastes at a low water-cement ratio (W/C = 0.22) through a systematic investigation on the rheological properties, adsorption properties, solution viscosity and polymer hydrodynamic radius. Adsorption data show that the adsorption amount of the block PC is larger than that of the random PC while the paste flow is the same even though the dosage of the former is smaller, possibly owing to the fact that the adsorbing carboxylic groups are concentrated at one end in the case of the block PC, and the absence of neutral side chains in the adsorbing block effectively reduces the free energy barrier of PC adsorption. Results on the polymer hydrodynamic radius from dynamic light scattering (DLS) illustrate that the hydrodynamic radius of the block PC is smaller than that of the random PC, and in consistence with the DLS results, the solution of the block PC is also found to have a lower viscosity at the same polymer weight concentration. It is worth-noting that the apparent viscosity of the cement paste has a close relation with the viscosity of PC remaining in solution. The dual effects of a larger adsorption amount and a smaller hydrodynamic radius of the block PC effectively reduce the viscosity of PC remaining in solution, and hence effective reduce the apparent viscosity of cement pastes. It is believed that this study allows for a better understanding of the influences of polycarboxylate architecture on rheological properties of cementitious materials.

Binding kinetics of blueberry pectin-anthocyanins and stabilization by non-covalent interactions

The effect of pectin composition on the binding selectivity to anthocyanins was investigated by Langmuir isotherms with two blueberry pectins, water soluble fraction (WSF) and chelator soluble fraction (CSF). Adsorption was four times higher between CSF and anthocyanins, than WSF and anthocyanins. Higher adsorption was attributed to the more linear, more negatively charged homogalacturonan region of CSF, compared to the more branched, neutral sugar rich WSF. The CSF binding sites (qmax) to anthocyanins were estimated at 1413–1904 μg/mg pectin, which was about eight times higher than WSF binding sites. No difference was observed in binding affinity (KL) among blueberry pectins. WSF, rich in neutral sugar side chains, showed lower and more variable interaction with anthocyanins. Binding studies also showed that blueberry pectin-anthocyanins adsorption was highest at pH 3.0 and lowest at pH 4.0. Increasing concentration from 25 to 200 mM citrate-phosphate (CP) weakened the pectin-anthocyanins interaction between pH values 3.0 and 4.0. However, no significant difference in binding was observed at pH 2.6 with increasing CP. As pH values changed from 4.0 to more acidic pH, electrostatic interaction decreased while hydrophobic interactions increased between blueberry pectin and anthocyanins, and hydrogen bond likely remained constant. Putative health benefits of anthocyanins are probably influenced by small pH and ionic strength changes in food matrixes.