Pectin methylesterase inhibitors GhPMEI53 and AtPMEI19 improve seed germination by modulating cell wall plasticity in cotton and Arabidopsis

The germination process of seeds is influenced by the interplay between two opposing factors,pectin methylesterase(PME)and pectin methylesterase inhibitor(PMEI),which collectively regulate patterns of pectin methylesterification.Despite the recognized importance of pectin methylesterification in seed germination,the specific mechanisms that govern this process remain unclear.In this study,we demonstrated that the overexpression of GhPMEI53is associated with a decrease in PME activity and an increase in pectin methylesterification.This leads to seed cell wall softening,which positively regulates cotton seed germination.AtPMEI19,the homologue in Arabidopsis thaliana,plays a similar role in seed germination to GhPMEI53,indicating a conserved function and mechanism of PMEI in seed germination regulation.Further studies revealed that GhPMEI53 and AtPMEI19 directly contribute to promoting radicle protrusion and seed germination by inducing cell wall softening and reducing mechanical strength.Additionally,the pathways of abscicic acid(ABA)and gibberellin(GA)in the transgenic materials showed significant changes,suggesting that GhPMEI53/AtPMEI19-mediated pectin methylesterification serves as a regulatory signal for the related phytohormones involved in seed germination.In summary,GhPMEI53 and its homologs alter the mechanical properties of cell walls,which influence the mechanical resistance of the endosperm or testa.Moreover,they impact cellular phytohormone pathways(e.g.,ABA and GA)to regulate seed germination.These findings enhance our understanding of pectin methylesterification in cellular morphological dynamics and signaling transduction,and contribute to a more comprehensive understanding of the PME/PMEI gene superfamily in plants.

AlphaFold-guided redesign of a plant pectin methylesterase inhibitor for broad-spectrum disease resistance

Plant cell walls are a critical site where plants and pathogens continuously struggle for physiological domi-nance.Here we show that dynamic remodeling of pectin methylesterification of plant cell walls is a compo-nent of the physiological and co-evolutionary struggles between hosts and pathogens.A pectin methyles-terase(PsPME1)secreted by Phytophthora sojae decreases the degree of pectin methylesterification,thus synergizing with an endo-polygalacturonase(PsPG1)to weaken plant cell walls.To counter PsPME1-mediated susceptibility,a plant-derived pectin methylesterase inhibitor protein,GmPMl1,protects pectin to maintain a high methylesterification status.GmPMl1 protects plant cell walls from enzymatic degrada-tion by inhibiting both soybean and P.sojae pectin methylesterases during infection.However,constitutive expression of GmPMl1 disrupted the trade-off between host growth and defense responses.We therefore used AlphaFold structure tools to design a modified form of GmPMI1(GmPMI1R)that specifically targets and inhibits pectin methylesterases secreted from pathogens but notfrom plants.Transient expression of GmPMi1R enhanced plant resistance to oomycete and fungal pathogens.In summary,our work highlights the biochemical modification of the cell wall as an important focal point in the physiological and co-evolutionary conflict between hosts and microbes,providing an important proof of concept that Al-driven structure-based tools can accelerate the development of new strategies for plant protection.

Pectin modulates intestinal immunity in a pig model via regulating the gut microbiota-derived tryptophan metabolite-AhR-IL22 pathway

Background Pectin is a heteropolysaccharide that acts as an intestinal immunomodulator,promoting intestinal development and regulating intestinal flora in the gut.However,the relevant mechanisms remain obscure.In this study,pigs were fed a corn-soybean meal-based diet supplemented with either 5%microcrystalline cellulose(MCC)or 5%pectin for 3 weeks,to investigate the metabolites and anti-inflammatory properties of the jejunum.Result The results showed that dietary pectin supplementation improved intestinal integrity(Claudin-1,Occludin)and inflammatory response[interleukin(IL)-10],and the expression of proinflammatory cytokines(IL-1β,IL-6,IL-8,TNF-α)was down-regulated in the jejunum.Moreover,pectin supplementation altered the jejunal microbiome and tryptophan-related metabolites in piglets.Pectin specifically increased the abundance of Lactococcus,Enterococcus,and the microbiota-derived metabolites(skatole(ST),3-indoleacetic acid(IAA),3-indolepropionic acid(IPA),5-hydroxyindole-3-acetic acid(HIAA),and tryptamine(Tpm)),which activated the aryl hydrocarbon receptor(AhR)pathway.AhR activation modulates IL-22 and its downstream pathways.Correlation analysis revealed the potential relationship between metabolites and intestinal morphology,intestinal gene expression,and cytokine levels.Conclusion In conclusion,these results indicated that pectin inhibits the inflammatory response by enhancing the AhR-IL22-signal transducer and activator of transcription 3 signaling pathway,which is activated through tryptophan metabolites.

Novel Pectin/Chia-Mucilage Membranes:Human Serum Albumin Adsorption,Biocompatibility,and Physical-Chemical Properties

This study aimed to characterize the physical-chemical and biological properties of pectin(PC)/chia seed mucilage(CM)membranes.PC/CM[100/0(control),80/20%,60/40%,and 40/60%w/w]membranes were prepared using the casting method.The membranes(PC/CM)were thin,yellow,lightly opaque(≈10%)and capable of blocking light UVB(between 66 at 52%).SEM analysis showed the presence of aggregates in the shape of a sphere(≈13μm)and ovoid(≈25μm).The proportion of 80/20 showed an increase in tensile strength(29%)and elastic modulus(19%)when compared to the control.FTIR analysis exhibited intermolecular interactions between PCPC,PC-CM,and CM-CM in the membranes.The thermal analysis(600°C)showed a slight improvement in the percentage of residual mass-loss of 3.31%(80/20)that control.The 40/60 membrane showed the lowest percentage of hemolysis(2.94%)but limited human albumin adsorption capacity.These results suggested that the blend PC/CM may be considered as a biomaterial for medical applications.

Pectin fractions extracted sequentially from Cerasus humilis:Their compositions,structures,functional properties and antioxidant activities

Three pectin fractions(water-soluble fraction(WSF),chelator-soluble fraction(CSF),and sodium carbonatesoluble fraction(NSF))were obtained from Chinese dwarf cherry(Cerasus humilis)fruits.All of them were branched low methoxylated pectins with an amorphous or partially nanocrystalline nature and eight neutral monosaccharides(arabinose and galactose were most abundant).WSF,CSF and NSF had a degree of methylation(DM)of 35.82%,14.85%and 7.13%,uronic acid(UA)content of 76.02%,83.71%and 69.01%,and total protein content of 2.4%,2.1%and 8.8%,respectively.Their molecular weights were 340.31,330.16 and 141.31 kg/mol,respectively(analyzed by gel permeation chromatography(GPC)).WSF,CSF and NSF exhibited good rheological,thermal,emulsifying,emulsion-stabilizing,water-adsorbing,oil-binding,cholesterol-binding and antioxidant properties.NSF had the highest emulsifying,emulsion stabilizing,water-/oil-/cholesterol-binding and antioxidant capacities,followed by CSF.NSF had the highest viscosity(406.77 m Pa·s),flowability,and resistance to heat-induced changes/damage,which may be related to its lowest polydispersity index,DM and UA content and highest protein content.The three pectin fractions with desirable characteristics can be used as food additives/ingredients and dietary supplements.

Identification and fermentation optimization of protopectinase-overproducing strain Aspergillus niger CD-01 for pectin production

In order to solve the citrus peel resource waste problem protopectinase-overproducing strain CD-01 for pectin production and minimize the drawbacks of chemical extraction of pectin, a was isolated from a pit soil dumped with perished orange in Changde City, Hunan Province of China. The strain CD-01 had the same morphology and 28S rRNA gene sequence （FJ184995） as that of Aspergillus niger （ATCC 64028）. It was thus identified and named as Aspergillus niger CD-01. The fermentation condition was optimized based on L9（34） orthogonal experimental design and the variances analyses. The results show that the optimal condition for producing pectin is as follows： time 36 h, temperature 35 ℃, pH 5, and urea as the nitrogen source. Under this condition, the pectin yield can reach up to 24.5%. This shows a great potential of Aspergillus niger CD-01 in pectin extraction from citrus.

Production of Pectinolytic Enzymes by Two Bacillus spp. Strains and Their Application in Flax Degumming

This study demonstrated that Bacillus licheniformis HDYM-03 and Bacillus megaterium HDYM-09, isolated from a liquid sample of fl ax retting pool, were able to produce pectinolytic enzymes using polysaccharides as substrates. Bacillus megaterium HDYM-09 produced pectin lyase that exhibited the highest activity of 2116.71 ± 11.55 U/mL. Bacillus licheniformis HDYM-03 produced pectate lyase that exhibited the highest activity of 611.21 ± 14.54 U/mL. Based on these fi ndings, we constructed four retting systems to degrade the pectin substance. The results showed that the content of galacturonic acid in the mixed system was 529.21 μg/mL, the content of reducing sugar was 98.14 mg/mL, and the weight loss ratio of cells reached 19.49%, which were signifi cantly higher than those in other systems. The mixed system has more advantages, and the utilization rate of degumming was higher, which further ensured that the degumming can be carried out effi ciently and quickly. The mixed system exhibits feasible applications in the fi ber and textile industry.

Optimization of the biphasic release of indomethacin from HPMC/pectin/calcium chloride matrix tablet by response surface methodology

We studied the effect of two independent variables, the pectin/calcium chloride weight ratio and the overall matrix weight in HPMC/pectin/calcium matrix tablet, on the release of indomethacin. A two-factor 5-level central composite experimental design was employed. Responses of the Peppas correlation parameters n and K and the 10% release time （T0.1） were optimized by response surface methodology. Significant effect of the independent variables on the biphasic release parameters, n and K, was observed. N, K and T0.1 were well fitted with the second-order quadratic equations rather than linear equations. Moreover, the mathematic fitting and the response surfaces showed significant cross-interaction between the pectin/calcium chloride ratio and the overall matrix weight. The optimal formulation with larger n, longer T0.1 and smaller K consisted of medium pectin/calcium chloride ratio around 1.0 and medium matrix weight around 200 mg. Validation studies on the optimal formulations showed good predictability of the n, K and T0.1 values with biases within the range of-7.33% and 6.26%. Our results support that central composite design can be used to optimize drug release from HPMC/pectin/calcium matrix tablet with high predictability.

Study on Extraction of Pectin from Orange Peels

The comparison was conducted to investigate the higher extraction rate between two methods including alcohol deposition with acid hydrolysis and micro- wave-assistant extraction technique. The experimental results showed that the former method led to a better extraction effect. For the method of alcohol deposition with acid hydrolysis, the technique parameters were optimized through I.s （34 ） orthogonal e^periment based on the results of single factor experiments, after investi- gated the effect of solid to liquid ratio, pH, extraction temperature and extraction time on the pectin extraction rate. tersrm technique was employed to extract pectin. The selected parameter was obtained by means On the basis of the optimal technical parmne- of L16 （45） orthogonal experiment after studied the effect of solid to liquid ratio, extraction temperature, microwave treatment period, pH and microwave power on pectin extraction yield. Repetitive examinations of two methods were carried out separately, pectin extraction rate with the fLrst technique was 14.57% and that with the second method was 11.62%. The charac- teristics of the pectin sample prepared by alcohol deposition with acid hydrolysis were further investigated. The research demonstrated that mass percent of pectin was 87.23%. The esterification degree of pectin was 75.66% ,and pectin sample color was from creamy white to pale yellow.

Relationship between Pectic Substances and Strand Separation of Cooked Spaghetti Squash--Part 2. Changes in Firmness, Histological Structure and Pectic Substances during Soaking in Pectin Extractants

The flesh of spaghetti squash separates into strands when cooked. The purpose of this paper is to investigate the cause of strand separation （during cooking） by soaking for 24 h at 35 ℃ in solutions with three kinds of pectin extractant. The changes in strand separation, firmness, histological structure and the pectin of flesh during soaking in 0.01 N HCI solution （pH 2.0）, 0.035 M ammonium oxalate solution （pH 4.0） or 2% sodium hexametaphosphate solution （pH 4.0） were investigated. When flesh was soaked in the HCI solution, the separation into strands and removal of calcium and magnesium were greater than that soaked in other pectin extractants. High methoxyl pectin was extracted by soaking in HC1 solution （pH 2.0） due to removal of polyvalent cations. This result shows that high methoxyl pectin glues strands together in the flesh of spaghetti squash. The shape of the cells which constituted strands was round; on the other hand, that of cells surrounded strands was elongated. When cooked in boiling water or soaked at pH 2.0, the shape of the former cells was maintained, but the latter cells, which contributed to adhesion between strands, broke down. Thus, the flesh separated into strands. When flesh was boiled for 15-30 min, pectin degraded and dissolved in the cooking solution; consequently, the flesh separated into strands and also the middle lamella of cell walls of strands separated. However, pectin remaining in strands maintained their crispness.

栉江珧(Atrina pectinata)EST-SSR标记的开发与应用

本研究以前期获得的栉江珧(Atrina pectinata)转录组数据为基础,筛选获得10550条微卫星标记(SSR),检出率为8.2%,平均9.01 kb出现1个SSR位点。设计并合成120对SSR引物,筛选得到36对能够稳定扩增的引物,并利用已获得的36对SSR引物对青岛海区栉江珧进行了群体遗传多样性分析。结果显示,12对引物的扩增片段表现出多态性,共产生42个等位基因,平均每个位点产生3.5个等位基因,平均观测杂合度(H_o)、平均期望杂合度(H_e)和平均多态信息含量(PIC)分别为0.417、0.604和0.526,表明青岛海区栉江珧群体的遗传多样性较高。本研究获得的EST-SSR标记和群体遗传信息为栉江珧的种质资源保护提供了重要的参考资料。

Standard triple, bismuth pectin quadruple and sequential therapies for Helicobacter pylori eradication

AIM: To compare the effectiveness of standard triple, bismuth pectin quadruple and sequential therapies for Helicobacter pylori (H. pylori ) eradication in a randomized, double-blinded, comparative clinical trial in China. METHODS: A total of 215 H. pylori -positive patients were enrolled in the study and randomly allocated into three groups: group A (n = 72) received a 10-d bismuth pectin quadruple therapy (20 mg rabeprazole bid , 1000 mg amoxicillin bid , 100 mg bismuth pectin qid , and 500 mg levofloxacin qd ); group B (n = 72) received the sequential therapy (20 mg omeprazole bid , 1000 mg amoxicillin bid , in 5 d, followed by 20 mg omeprazole bid , 500 mg tinidazole bid , 500 mg clarithromycin bid , for another 5 d); group C (n = 71) received a standard 1-wk triple therapy (20 mg omeprazole bid , 1000 mg amoxicillin bid , 500 mg clarithromycin bid ). After all these treatments, 20 mg omeprazole bid was administrated for 3 wk. H. pylori status was assessed by histology, 13C-urea breath test and rapid urease test at baseline and 4-6 wk after completion of treatment. Ulcer cicatrization was assessed by gastroscopy. χ 2 test (P < 0.05) was used to compare the eradication rates and ulcer cicatrisation rates among the three groups. RESULTS: The eradication rate was 83.33% (60/72) in group A, 88.89% (64/72) in group B, and 80.56% (58/71) in group C. The ulcer cicatrisation rate was 86.44% (51/59) in group A, 90.16% (55/61) in group B, and 84.91% (45/53) in group C. The sequential therapy yielded a higher eradication rate and ulcer cicatrisation rate than the standard triple and bismuth pectin quadruple therapies. Statistically, the eradication rate of group B was significantly different from groups A and C (P < 0.05), but the difference of ulcer cicatrisation rate and side effects was not statistically significant among the three groups (P > 0.05). The three protocols were generally well tolerated. CONCLUSION: The sequential therapy has achieved a significantly higher eradication rate, and is a more suitable first-line alternative protocol for anti-H. pylori infection compared with the standard triple and bismuth pectin quadruple therapies.

Inhibitory effect of modified citrus pectin on liver metastases in a mouse colon cancer model

AIM: To discuss the expression of glactin-3 in liver metastasis of colon cancer and its inhibition by modi- fied citrus pectin (MCP) in mice. METHODS: Seventy-five Balb/c mice were randomly di- vided into negative control group (n = 15), positive con- trol group (n = 15), low MCP concentration group (n = 15), middle MCP concentration group (n = 15) and high MCP concentration group (n = 15). CT26 colon cancer cells were injected into the subcapsule of mouse spleen in positive control group, low, middle and high MCP concentrations groups, except in negative control, to set up a colon cancer liver metastasis model. The concen- tration of MCP in drinking water was 0.0%, 0.0%, 1.0%, 2.5% and 5.0% (wt/vol), respectively. Liver metastasis of colon cancer was observed after 3 wk. Enzyme-linked immunosorbent assay (ELISA) was used to detect the concentration of galectin-3 in serum. Expression of ga- lectin-3 in liver metastasis was detected by immunohis- tochemistry. RESULTS: Except for the negative group, the percent- age of liver metastasis in the other 4 groups was 100%, 80%, 73.3% and 60%, respectively. The number of liver metastases in high MCP concentration group was significantly less than that in positive control group (P = 0.008). Except for the negative group, the median volume of implanted spleen tumor in the other 4 groups was 1.51 cm3, 0.93 cm3, 0.77 cm3 and 0.70 cm3, respec- tively. The volume of implanted tumor in middle and high MCP concentration groups was significantly smaller than that in positive control group (P = 0.019; P = 0.003). The concentration of serum galectin-3 in positive control and MCP treatment groups was significantly higher than that in the negative control group. However, there was no significant difference between them. Except for the negative control group, the expression of galectin-3 in liver metastases of the other 4 groups showed no sig- nificant difference. CONCLUSION: Expression of galetin-3 increases sig- nificantly in liver metastasis of colon cancer, which can be effectively inhibited by MCP.

Novel modified pectin for heavy metal adsorption

Modified pectin cross-linked with adipic acid, was synthesized and used for heavy metal removal from wastewater. SEM and FTIR were used to investigate its structure and morphology. The modified pectin had a rough, porous phase covered with carboxy groups, resulting a high adsorption capacity. And at the room temperature, the saturated loading capacity for Pb^2＋, Cu^2＋ and Zn^2＋ reached 1.82 retool/g, 1.794 mmol/g and 0.964 retool/g, respectively. The results proved its potential application to remove of the heavy metal.

Effect of high-pressure homogenization on stability of emulsions containing zein and pectin

The aim of this study was to investigate the effect of high-pressure homogenization on the droplet size and physical stability of different formulations of pectin–zein stabilized rice bran oil emulsions. The obtained emulsions, both before and after passing through highpressure homogenizer, were subjected to stability test under environmental stress conditions,that is, temperature cycling at 4 °C/40 °C for 6 cycles and centrifugal test at 3000 rpm for 10 min. Applying high-pressure homogenization after mechanical homogenization caused only a small additional decrease in emulsion droplet size. The droplet size of emulsions was influenced by the type of pectin used;emulsions using high methoxy pectin(HMP) were smaller than that using low methoxy pectin(LMP). This is due to a greater emulsifying property of HMP than LMP. The emulsions stabilized by HMP–zein showed good physical stability with lower percent creaming index than those using LMP, both before and after passing through high-pressure homogenizer. The stability of emulsions after passing through high-pressure homogenizer was slightly higher when using higher zein concentration, resulting from stronger pectin–zein complexes that could rearrange and adsorb onto the emulsion droplets.

Characterization and in vitro release studies of oral microbeads containing thiolated pectin–doxorubicin conjugates for colorectal cancer treatment

Novel oral microbeads were developed based on a biopolymer–drug conjugate of doxorubicin(DOX) conjugated with thiolated pectin via reducible disulfide bonds. The microbeads were fabricated by ionotropic gelation with cations such as Al3+, Ca2+ and Zn2+. The results showed that using zinc acetate can produce the strongest microbeads with spherical shape.However, the microbeads prepared from thiolated pectin–DOX conjugate were very soft and irregular in shape. To produce more spherical microbeads with suitable strength, the native pectin was then added to the formulations. The particle size of the microbeads ranged from 0.87 to 1.14 mm. The morphology of the microbeads was characterized by optical and scanning electron microscopy. DOX was still in crystalline form when used in preparing the microbeads, as confirmed by powder X-ray diffractometry. Drug release profiles showed that the microbeads containing thiolated pectin–DOX conjugate exhibited reduction-responsive character;in reducing environments, the thiolated pectin–DOX conjugate could uncouple resulting from a cleavage of the disulfide linkers and consequently release the DOX. The best-fit release kinetics of the microbeads containing thiolated pectin–DOX conjugate, in the medium without reducing agent, fit the Korsmeyer–Peppas model while those in the medium with reducing agent fit a zero-order release model. These results suggested that the microbeads containing thiolated pectin–DOX conjugate may be a promising platform for cancer-targeted delivery of DOX, exploiting the reducing environment typically found in tumors.

米曲霉果胶酸酯裂解酶(pectin lyase 1)在原核系统中重组表达

来自米曲霉(Aspergillus oryzae)和黑曲霉(Aspergillus niger)的果胶酸酯裂解酶(pectinlyase)一直被用于传统发酵食品的生产,但自然条件下A.oryzae和A.niger的果胶酸酯裂解酶产量较低。通过RT-PCR的方法,获得不含信号肽的A.oryzaePel1cDNA,将Pel1cDNA连入pET-28a(+)载体,构建pET-28a(+)-pel1质粒。pET-28a(+)-pel1转化Turner(DE3)placⅠ细胞,得到转化子pET-28a(+)-pel1-Turner(DE3)placⅠ,表达与6个组氨酸融合的Pel1。进一步对Pel1在E.coli系统中表达的条件进行了研究,在37℃,220r/min条件下,培养pET-28a(+)-pel1-Turner(DE3)placⅠ细胞,当OD600至0.8左右时,用500μmol/Lisopropylβ-D-thiogalactogalactop-yranoside(IPTG)进行诱导表达,在15℃和170r/min条件下,继续培养60h后,表达效果最好,产酶可达到400u/mL,是A.oryzae自然条件下产酶量的4000倍,也高于已报道的真菌果胶酸酯裂解酶在真菌体系中重组表达的效果。

Optimization of pectin extraction and antioxidant activities from Jerusalem artichoke

Jerusalem artichoke is an economic crop widely planted in saline-alkaline soil. The use of Jerusalem artichoke is of great significance. In this study, the response surface method was employed to optimize the effects of processing variables （extraction temperature, pH, extraction time, and liquid-to- solid ratio） on the yield of Jerusalem artichoke pectin. Under the optimal extraction conditions： pHl .52, 63.62 min, 100℃ and a liquid-to-solid ratio of 44.4 mL/g, the maximum pectin yield was predicted to be 18.76%. Experiments were conducted under these optimal conditions and a pectin yield of 18.52＋0.90% was obtained, which validated the model prediction. The effects of different drying methods （freeze drying, spray drying and vacuum drying） on the properties of Jerusalem artichoke pectin were evaluated and they were compared with apple pectin. FTIR spectral analysis showed no major structural differences in Jerusalem artichoke pectin samples produced by various drying treatments. The antioxidant activities of pectin dried by different methods were investigated using in vitro hydroxyl and DPPH radical scavenging systems. The results revealed that the activities of spray dried pectin （SDP） and apple pectin （AP） were stronger than those of vacuum oven dried pectin （ODP） and vacuum freeze dried pectin （FDP）. Therefore compared with the other two drying methods, the spray drying method was the best.

Characteristics, Enzymatic Extraction of Pectin from Shaddock

Pectins had been extracted from shaddock raw material with 0.01 mol·L^-1 HCI and with three enzymic preparations including cellulase from aspergillus oryzaei.β -glucosidase from almonds and protopectinases-T, a protopectin-solubilizing enzyme, which did not degrade polygalacturonic acid, The effects of enzymic and acid soluhilization of pectin from shaddock materials were compared, The yield of pectin preparations, degree of acetylation, gelling strength, molecular weight and viscosity were determined. Enzymic methods of extraction gave much bigger yields of pectic substances. Compared with the pectin extracted with hydrochloric acid, all the samples derived from shaddock raw material with enzymic preparations had a significant lower D-galacturonic acid content.

Structure Analysis of Pectin SB_(1-1) from the Root of Panax ginseng

A water-soluble pectin SB_~1-1 was isolated and purified from the root of Panax ginseng C. A. Mey. The HPLC analysis indicates that SB_~1-1 is homogenous. Its molecular weight was estimated via gel filtration to be 10000. The GC analysis indicated that it contains the monosaccharides of GalA, Gal, Ara and Rha. Their molar ratio is 2.10∶1.00∶0.12∶0.13. Partial hydrolysis with acid, pectinase treatment, periodate oxidation, Smith degradation, methylation analyses, GC/MS analyses and NMR analyses were used for the structure analyses of SB_~1-1 . The results reveal that SB_~1-1 has a lower branched structure. The main chain is composed of GalA and Gal; the inner part is α-1,4-linked-GalA; the border is 1,4-linked-Gal. Some of the 1,4-linked-GalA and 1,4-linked-Gal residues are substituted at O6. On an average, there is one branch for every ten hexose residues. The side chain is composed of 1,6-linked-Gal and 1,3,6-linked-Gal. The nonreduced end is composed of Rha, Ara and Gal. The main glycosidic link of SB_~1-1 has an α configuration.