Cytotoxicity and antibacterial susceptibility assessment of a newly developed pectin-chitosan polyelectrolyte composite for dental implants.

Biopolymers such as chitosan and pectin are currently attracting significant attention because of their unique properties, which are valuable in the food industry and pharmaceutical applications. These properties include non-toxicity, compatibility with biological systems, natural decomposition ability, and structural adaptability. The objective of this study was to assess the performance of two different ratios of pectin-chitosan polyelectrolyte composite (PCPC) after applying them as a coating to commercially pure titanium (CpTi) substrates using electrospraying. The PCPC was studied in ratios of 1:2 and 1:3, while the control group consisted of CpTi substrates without any coating. The pull-off adhesion strength, cytotoxicity, and antibacterial susceptibility tests were utilized to evaluate the PCPC coatings. In order to determine whether the composite coating was the result of physical blending or chemical bonding, the topographic surface parameters were studied using Fourier transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM). PCPC (1:3) had the highest average cell viability of 93.42, 89.88, and 86.85% after 24, 48, and 72 h, respectively, as determined by the cytotoxicity assay, when compared to the other groups. According to the Kirby-Bauer disk diffusion method for testing antibacterial susceptibility, PCPC (1:3) showed the highest average diameter of the zone of inhibition, measuring 14.88, 14.43, and 11.03 mm after 24, 48, and 72 h of incubation, respectively. This difference was highly significant compared to Group 3 at all three time periods. PCPC (1:3) exhibited a significantly higher mean pull-off adhesion strength (521.6 psi) compared to PCPC (1:2), which revealed 419.5 psi. PCPC (1:3) coated substrates exhibited better surface roughness parameters compared to other groups based on the findings of the AFM. The FTIR measurement indicated that both PCPC groups exhibited a purely physical blending in the composite coating. Based on the extent of these successful in vitro experiments, PCPC (1:3) demonstrates its potential as an effective coating layer. Therefore, the findings of this study pave the way for using newly developed PCPC after electrospraying coating on CpTi for dental implants.

Characteristics of soy films as affected by transglutaminase cross-linking and inclusions of pectin and protein enhancers.

Previously, we showed that water extract (soymilk, except pH was increased to 8 from 6.5) of whole soybean could be used directly as a raw material for producing edible soy films by deposition of the film-forming solution (soy extract with enhancers). However, the strength of such soy films needed improvement because they were weak. The purpose of this study was to investigate how transglutaminase (TG) cross-linking reactions and film enhancers, including pectin (low- and high-methoxyl pectin), whey protein isolate (WPI), and soy protein isolate (SPI), improve the physical properties of soy films. Soy films prepared with TG had tensile strength (TS) of 3.01 MPa and puncture strength (PS) of 0.78 MPa, which were higher by as much as 51% and 30% than that of soy films without TG treatment, respectively. Pectin showed significant effects on the mechanical properties of TG-added soy films in terms of TS, PS, and % elongation. On the other hand, only TS and PS were increased by the addition of WPI or SPI. Heat curing had a significant effect on soy film's physical properties. TG treatment significantly reduced film solubility when soaked in water and various levels of acid (vinegar) and base (baking soda) solutions. Under the experimental conditions of 35 unit TG and 28 min of reaction, the degrees of cross-linking were evidenced by the disappearance of individual protein subunits, except the basic subunit of glycinin, and the reduction of 21% of lysine residues of the proteins. HIGHLIGHTS: Edible soy films were made with transglutaminase and about 21% lysine cross-linked. The mechanical strength of soy films was increased by incorporating film enhancers. Transglutaminase enhanced the mechanical properties of soy films.

Adsorption performance and mechanism of pectin modified with ß-cyclodextrin for Zn2+ and Cu2.

Removing heavy metals from aqueous solutions has drawn more and more attentions these years because of their serious global health challenge to human society. To develop an adsorbent with green, stable and high-efficiency for adsorption of heavy metals, pectin ß-cyclodextrin composite was successfully prepared and used for Zn2+ and Cu2+ adsorption for the first time. Various variables that influence the adsorption performance were explored, and the optimal adsorption conditions were determined. According to the pseudo-second-order kinetic model, the adsorption process of Zn2+ and Cu2+ by the adsorbent was mainly chemical adsorption. The adsorbent adsorption process was an exothermic and non-spontaneous process. According to the Langmuir isotherm model, the maximum adsorption capacity was 12.51 ± 0.33 and 24.98 ± 0.23 mg/g for Zn2+ and Cu2+, respectively. The FTIR, EDX and XPS results revealed that the main mechanisms of removing pollutants by adsorbent were ion exchange and coordination. In addition, electrostatic attraction and chelation were present in the adsorption process. After five adsorption desorption cycles, the pectin ß-cyclodextrin composite adsorbent still exhibited adsorption and regeneration capabilities. This study provides a low-cost, effective and simple method for preparation of modified pectin, which has excellent application potential in the removal of heavy metal ions from wastewater.

Structure characterization and gelling properties of RG-I-enriched pectins extracted from citrus peels using four different methods.

To facilitate the application of rhamnogalacturonan-I (RG-I)-enriched pectins (RGPs) as novel, healthy, and gelling food additives, this study compared the structural characteristics and gelling properties of RGPs extracted from citrus peel via four methods (alkali: AK, high-temperature/pressure: TP, citric acid: CA, and enzyme-assisted: EA extractions). AK and CA yielded pectins with the highest RG-I proportions (54.8 % and 51.9 %, respectively) by disrupting the homogalacturonan region; TP and EA increased the RG-I proportions by ~10 %. Among the four methods, AK induced the lowest degree of esterification (DE) (6.7 %) and longer side chains that form strong entanglement, contributing to its highest gel hardness. The relatively low DE (18.5 %) of CA RGP facilitated stable gel formation. Notably, its highly branched RG-I region afforded more intramolecular hydrophobic interactions, making a more highly cross-linked gel network of better gel resilience. In contrast, TP induced the highest DE (57 %) and curved molecular chains; it inhibited Ca2+ binding, entanglement, and intramolecular hydrophobic interactions, and thus no gel formed. EA RGP was associated with the lowest molecular size, rendering it more difficult for Ca2+ to form links, which resulted no gel. These findings offer insights into the relationship among the extraction methods, molecular structures, and gelling properties of RGPs.

Characterization of a novel sulfated-rhamnoglucuronan isolated from Korean seaweed Ulva pertusa and its efficacy for treatment of inflammatory bowel disease in mice.

This study aimed to isolate Ulva pertusa polysaccharide (UPP), which elicits anti-inflammatory bowel disease (IBD) effects, from the Korea seaweed U. pertusa and identify its structure. Firstly, UPP was isolated from U. pertusa using hydrothermal extraction and ethanol precipitation. UPP is a novel polysaccharide that exhibits unique structural features such as 3-sulfated rhamnose, glucuronic acid, iduronic acid, and 3-sulfated xylose, which are repeated in 1,4-glycosidic bonds. Prophylactic oral administration of UPP in mice with dextran sulfate sodium (DSS)-induced ulcerative colitis (UC) suppressed the levels of inflammatory cytokines and MAPK- and NF-κB-related factors in the serum and colon tissue. Tight junction (TJ)-related factors such as occludin, claudin-1, and mucin were effectively augmented by UPP in the colon tissue. In addition, UPP administration prevented the DSS treatment-led cecal short chain fatty acid imbalance, and this effect was most evident for propionic acid. In conclusion, UPP isolated from the Korean U. pertusa demonstrates potent anti-IBD activity. Characterization of this ulvan revealed its unique structure. Moreover, its efficacy may be associated with its anti-inflammatory effects and regulation of gut microbiota and TJ proteins. Thus, this study provides new insights into the biological effects of UPP in IBD.

Arabinoxylo-oligosaccharides production from unexploited agro-industrial sesame (Sesamum indicum L.) hulls waste.

This work demonstrates that sesame (Sesamum indicum L.) hull, an unexploited food industrial waste, can be used as an efficient source for the extraction of hemicellulose and/or pectin polysaccharides to further obtain functional oligosaccharides. Different polysaccharides extraction methods were surveyed including alkaline and several enzymatic treatments. Based on the enzymatic release of xylose, arabinose, glucose, and galacturonic acid from sesame hull by using different enzymes, Celluclast®1.5 L, Pectinex®Ultra SP-L, and a combination of them were selected for the enzymatic extraction of polysaccharides at 50 °C, pH 5 up to 24 h. Once the polysaccharides were extracted, Ultraflo®L was selected to produce arabinoxylo-oligosaccharides (AXOS) at 40 °C up to 24 h. Apart from oligosaccharides production from extracted polysaccharides, alternative approaches for obtaining oligosaccharides were also explored. These were based on the analysis of the supernatants resulting from the polysaccharide extraction, alongside a sequential hydrolysis performed with Celluclast®1.5 L and Ultraflo®L of the starting raw sesame hull. The different fractions obtained were comprehensively characterized by determining low molecular weight carbohydrates and monomeric compositions, average Mw and dispersity, and oligosaccharide structure by MALDI-TOF-MS. The results indicated that sesame hull can be a useful source for polysaccharides extraction (pectin and hemicellulose) and derived oligosaccharides, especially AXOS.

Tuning bio-aerogel properties. Part 3: Exploring silica-pectin composite aerogels for drug delivery.

The release of the model drug theophylline from silica-pectin aerogels was investigated. The composite aerogels were prepared via impregnation of pectin alcogels with silica sol, followed by in situ silica gelation and drying with supercritical CO2. The structural and physico-chemical properties of the aerogels were tuned via the preparation conditions (type of silica sol, calcium crosslinking of pectin or not). Theophylline was loaded via impregnation and its release into simulated gastric fluid was studied during 1 h followed by release into simulated intestinal fluid. The swelling, mass loss and theophylline release behavior of the composites were analyzed and correlated with material properties. It followed that only aerogels prepared with calcium-crosslinked pectin and polyethoxydisiloxane were stable in aqueous systems, exhibiting a slow theophylline release governed by near-Fickian diffusion.

Effect of Organic Acid-Aided Extraction on Characteristics and Functional Properties of Pectin from Cannabis sativa L.

The extraction of cannabinoids from the inflorescence and leaves of Cannabis sativa L. is gaining interest from researchers, in addition to addressing the under-utilization of the by-products in the stems and roots of the trees. The present study investigated the recovery of pectin from the left-over parts of hemp tress using an eco-friendly method with the aid of organic acids. Different cannabis cultivars-Chalotte's Angels (CHA) and Hang-Krarog (HKR)-were used as plant materials. The stems of both cannabis cultivars contained more pectin than the roots, and tartaric acid-aided extraction provided higher yields than from citric acid. Extracting the acid solution affected some characteristics, thereby differentiating the functional properties of the derived pectin. Extraction using tartaric acid provided pectin with a higher galacturonic acid content, whereas pectin with a higher methylation degree could be prepared using citric acid. The pectin samples extracted from the stems of CHA (P-CHA) and HKR (P-HKR) had low methoxyl pectin. P-CHA had better free radical scavenging capability, whereas P-HKR showed more potent reducibility. Considering the functional properties, P-CHA showed greater emulsion formability and foaming activity, whereas P-HKR possessed a better thickening effect. The present work suggests the feasible utilization of P-CHA and P-HKR as food additives with bioactivity.

Pectin forms polymeric pigments by complexing anthocyanins during red winemaking and ageing.

The long-term stability of red wine color depends on the formation of polymeric pigments from anthocyanins. Although there is still a lot of uncertainty about the specific structure of this diverse group of pigments, there is consensus that they are reaction products of anthocyanins and other polyphenols. Interactions between anthocyanins and pectic polysaccharides have been suggested to stabilize anthocyanins. This study explores the impact of such interactions by adding pectin during red winemaking. The results demonstrate that these interactions induce the formation of additional polymeric pigments which enhance the pigment stability during fermentation and aging. While initial pigment formation is higher in wines with added pectin, a notable proportion of the complexes degrades in the later stages of fermentation. Presumably, tannins form insoluble complexes with pectin, reducing tannin concentration by more than 300 mg/L. Anthocyanin concentrations decrease by over 400 mg/L, and polymeric pigments double. Anthocyanins that form polymeric pigments with pectic polysaccharides expand the range of pigments in red wines with possible consequences for the sensory properties of the wine. These findings highlight the complex interactions between pectin, anthocyanins, and tannins, and their influence on pigment formation and wine composition during fermentation and aging.

Intestinal lymphatic transport of Smilax china L. pectic polysaccharide via Peyer's patches and its uptake and transport mechanisms in mononuclear phagocytes.

Recently, the intestinal lymphatic transport based on Peyer's patches (PPs) is emerging as a promising absorption pathway for natural polysaccharides. Herein, the aim of this study is to investigate the PP-based oral absorption of a pectic polysaccharide from Smilax china L. (SCLP), as well as its uptake and transport mechanisms in related immune cells. Taking advantages of the traceability of fluorescently labeled SCLP, we confirmed that SCLP could be absorbed into PPs and captured by their mononuclear phagocytes (dendritic cells and macrophages) following oral administration. Subsequently, the systematic in vitro study suggested that the endocytic mechanisms of SCLP by model mononuclear phagocytes (BMDCs and RAW264.7 cells) mainly involved caveolae-mediated endocytosis, macropinocytosis and phagocytosis. More importantly, SCLP directly binds and interacts with toll-like receptor 2 (TLR2) and galectin 3 (Gal-3) receptor, and was taken up by mononuclear phagocytes in receptor-mediated manner. After internalization, SCLP was intracellularly transported primarily through endolysosomal pathway and ultimately localized in lysosomes. In summary, this work reveals novel information and perspectives about the in vivo fate of SCLP, which will contribute to further research and utilization of SCLP and other pectic polysaccharides.

Biogenic Waste from Two Varieties of Plantain in Ghana Contain Pectin with Potential Binding Properties in Conventional Tablets.

Pharmaceutical formulations have traditionally relied on plants and their derivatives for various APIs and excipients. In Ghana, the widespread utilization of plantains, irrespective of their ripeness, generates significant waste at every stage of processing, posing disposal issues. Fascinatingly, these wastes, often discarded, possess significant economic potential and can be recycled into valuable raw materials or products. Pectin, a polysaccharide that occurs naturally, has seen a surge in interest in recent times. It has found widespread use in the pharmaceutical sector, particularly as a binding agent in tablet formulations. This study aimed to evaluate pectin from two popular plantain varieties, Apem (M) and Apantu (T) at different ripening stages, for pharmaceutical use as a binding agent in immediate-release tablets. The ripening stages selected were the matured-green (G), half-ripe (H), and full-ripe (R). Acid (D) and alkaline (L) mediums of extraction were employed for each ripening stage for both varieties. Wet granulation method was used to prepare the granules using paracetamol as a model drug, and their flow properties were subsequently assessed. Postcompression tests including, hardness, friability, weight uniformity, disintegration, assay, and in vitro dissolution were also assessed. Granules from all formulation batches had good flow properties indicated by their angle of repose (14.93 ± 1.41-21.80 ± 1.41), Hausner ratio (0.96 ± 0.27-1.22 ± 0.02), and compressibility (%) (7.69 ± 0.002-20.51 ± 0.002). All the tablets passed the uniformity of weight with none deviating by ±5%. The hardness of all the formulated tablets ranged between 3.96 ± 0.32 and 13.21 ± 0.36, while the friability for all tablets was below 1%. The drug content was between 100.1 ± 0.23% and 103.4 ± 0.01%. Tablets formulated with pectin as a binding agent at concentrations of 10% w/v and 15% w/v successfully met the disintegration test criteria for immediate release tablets. However, those prepared with a concentration of 20% w/v (MGL, MHD, MHL, MRD, MRL, TGL, THD, THL, and TRL) did not pass the disintegration test. Consequently, all batches of tablets successfully met the dissolution test requirement (Diss, Q > 75%), except for the batches that did not pass the disintegration test (Diss, Q < 75%). Ultimately, pectins extracted from the peels of Apem and Apantu at different ripening stages using acid and alkaline extraction can be commercially exploited as pharmaceutical binders at varying concentrations in immediate-release tablets.

Variety, growing conditions and processing method act on different structural and biochemical traits to modify viscosity in tomato puree.

The texture of tomato products can be modified by choice of variety, their growing conditions and/or processing method, but no clear explanation exists of the mechanisms that transform fruit tissue, how they act on texture, or whether genetics and processing impact the same physical parameters. We therefore conducted a study that processed 4 varieties produced under low/high nitrogen supply, into puree using both hot and cold break processes. No specific rheological signature allows discrimination between cultivar-induced or process-induced textural changes, but that they can be distinguished by sensory analysis. Growth conditions impacted but was not sensory distinguished. Both caused significant variations in 7 of 11 physico-chemical parameters, but the order of importance of these traits controlling texture varied, depending on whether the cause was genetic or process-related. Analysis of alcohol insoluble solids revealed a specific signature in pectin composition and conformation that could be linked to particle aggregation in the presence of lycopene-rich particles.

The interactions of pectin with TiO2 nanoparticles measured by FT-IR are confirmed in a model of the gastrointestinal tract.

The presence of nanoparticle fractions (<100 nm, NPs) in the food additive TiO2 (E171) rises concerns about its potential harmful impact on human health. The knowledge about the interaction of TiO2 NPs with food components is limited to proteins or polyphenols. The present paper is the first to report on interactions between TiO2 NPs and high molecular pectins that form gels in boluses and are remain nearly intact during digestion until they reach the colon. Direct interactions were studied using Fourier Transform Infrared Spectroscopy while indirect ones were monitored by measuring the "absorption" of TiO2 using a 0.2 microfiltration membrane, during in vitro digestion in a model of the gastro-intestinal tract. The FT-IR spectra registered for pectin-TiO2 NPs solutions confirmed changes in band intensities at 1020, 1100, 1610, and 1740 cm-1, suggesting interactions taking place mainly via the COO- groups. Furthermore, the I(1020)/I(1100) ratio was decreased (C-O stretching vibrations), suggesting partial blocking of the skeletal vibrations caused by interactions between pectin and TiO2. The modelled in vitro digestions confirmed that the "availability" of Ti was reduced when TiO2 NPs were combined with pectin, as compared to TiO2 NPs "digested" alone.

Encapsulation of Lactobacillus plantarum in W1/O/W2 double emulsions stabilized with the high-intensity ultrasound-treated pea protein and pectin.

This study focuses on developing a water-in-oil-in-water (W1/O/W2) double emulsion system using high-intensity ultrasound (HIU)-treated pea protein isolate (HIU-PPI) and pectin to encapsulate Lactobacillus plantarum (L. plantarum). The effects of ultrasound treatment on pea protein isolate (PPI) characteristics such as solubility, particle size, emulsification, surface hydrophobicity, and surface free sulfhydryl group were examined, determining optimal HIU processing conditions was 400 W for 10 min. The developed W1/O/W2 double emulsion system based on HIU-PPI demonstrated effective encapsulation and protection of L. plantarum, especially at the HIU-PPI concentration of 4 %, achieving an encapsulation efficiency of 52.65 %. Incorporating both HIU-PPI and pectin as emulsifiers increased the particle size and significantly enhanced the emulsion's viscosity. The highest bacterial encapsulation efficiency of the emulsion, 59.94 %, was attained at a HIU to pectin concentration ratio of 3:1. These emulsions effectively encapsulate and protect L. plantarum, with the concentration of HIU-PPI being a critical factor in enhancing probiotic survival under simulated gastrointestinal digestion. However, the concurrent utilization of pectin and HIU-PPI as emulsifiers did not provide a notable advantage compared to the exclusive use of HIU-PPI in enhancing probiotic viability during in vitro simulated digestion. This research offers valuable perspectives for the food industry on harnessing environmentally friendly, plant-based proteins as emulsifiers in probiotic delivery systems. It underscores the potential of HIU-modified pea protein and pectin in developing functional food products that promote the health benefits of probiotics.

Interfacial multilayer self-assembly of protein and polysaccharides: Ultrasonic regulation, stability and application in delivery lutein.

In this study, the layer-by-layer adsorption behavior of sodium caseinate, pectin, and chitosan on the oil-water interface was illustrated using multi-frequency ultrasound. We investigated the impact of ultrasound on various factors, such as particle size, zeta potential, and interfacial protein/polysaccharide concentration. It was observed that ultrasound has significantly decreased droplet size and increased the surface area at the interface, hence promoting the adsorption of protein/polysaccharide. In the sonicated multilayer emulsion, the concentrations of interface proteins, pectin, and chitosan increased to 84.82 %, 90.49 %, and 83.31 %, respectively. The findings of the study indicated that the application of ultrasonic treatment had a significant impact on the emulsion's surface charge and the prevention of droplet aggregation. As a result, the stability of the emulsion system, including its resistance to salt, temperature, and storage conditions, has been significantly improved. Moreover, the emulsion showed an increase in the retention rate of lutein by 21.88 % after a high-temperature water bath and by 19.35 % after UV irradiation. Certainly, the multilayer emulsion treated with ultrasound demonstrated a superior and prolonged releasing behavior. These findings demonstrated the suitability of the ultrasound treatment for the preparation of emulsions to deliver bioactive compounds.

Interplay between structure and signaling.

Modification of pectin, a component of the plant cell wall, is required to facilitate signaling by a RALF peptide, which is essential for many physiological and developmental processes.

Chitosan, gelatin and pectin based bionanocomposite films with rosemary essential oil as an active ingredient for future foods.

Bionanocomposite films of three biopolymers including chitosan, gelatin, and pectin incorporated with rosemary essential oil (REO) were developed and characterized in terms of their physical, structural, mechanical, morphological, antioxidant, and antimicrobial properties. Incorporation of REO showed an increased hydrophobic nature thus, improved water vapor transmission rate (WVTR), tensile strength (TS), elongation-at-break (EAB), and thermal stability significantly (P ≤ 0.05) as compared to the control films. The addition of REO leads to more opaque films with relatively increased microstructural heterogeneity, resulting in an increase in film opacity. Fourier transform infrared spectroscopy (FTIR) and particle size revealed that REO incorporation exhibits high physicochemical stability in chitosan, gelatin, and pectin bionanocomposite films. Incorporation of REO exhibited the highest inhibitory activity against the tested pathogenic strains (Bacillus subtilis and Escherichia coli). Furthermore, the addition of REO increased the inhibitory activity of films against ABTS and DPPH free radicals. Therefore, chitosan, gelatin, and pectin-based bionanocomposite films containing REO as food packaging could act as a potential barrier to extending food shelf life.

Amiodarone chewable gels as a potential appproach for paediatric congenital cardiopathies treatment: Comparison between animal and vegetal gelling agents.

The difficulty in swallowing is a frequent problem when oral solid dosage forms (conventional tablets or capsules) are administered to paediatric population or patients with dysphagia. An interesting alternative to overcome these problems are non-conventional formulations like chewable gels, commonly known as 'gummies'. Therefore, this work addresses the design, development and characterization of gummies using gelatine and pectin, for the vehiculization of the antiarrhythmic amiodarone (AMIO). Applying a Design of Experiments (DoE) approach, four gelatine (GG1-GG4) and eight pectin formulations (PG1-PG8) were developed. Considering the obtained results for responses during DoE evaluation (i.e., volume, syneresis, hardness, and gumminess), GG3 and PG8 were selected for complete characterization. Water activity, pH, drug content, texture parameters (adhesiveness, springiness, cohesiveness, and fracturability), disintegration time, in vitro dissolution, and microbiological features were evaluated. The obtained results were within the expected values for this type of formulation. The dissolution profiles showed a 94 % - 99 % of the AMIO content released for GG3 and PG8, respectively, so they could be considered suitable as immediate release dosage forms. In conclusion, the chewable gels were successfully developed and characterised, suggesting a potential means to accomplish a final prototype for the improvement of congenital cardiopathies treatment.

Unveiling novel insights into Bacillus velezensis 16B pectin lyase for improved fruit juice processing.

Microbial pectinolytic enzymes are important in various industries, particularly food processing. This study focuses on uncovering insights into a novel pectin lyase, BvPelB, from Bacillus velezensis 16B, with the aim of enhancing fruit juice processing. The study examines the structural and functional characteristics of pectinolytic enzyme, underscoring the critical nature of substrate specificity and enzymatic reaction mechanisms. BvPelB was successfully expressed and purified, exhibiting robust activity under alkaline conditions and thermal stability. Structural analysis revealed similarities with other pectin lyases, despite limited sequence identity. Biochemical characterization showed BvPelB's preference for highly methylated pectins and its endo-acting mode of cleavage. Treatment with BvPelB significantly increased juice yield and clarity without generating excessive methanol, making it a promising candidate for fruit juice processing. Overall, this study provides valuable insights into the enzymatic properties of BvPelB and its potential industrial applications in improving fruit juice processing efficiency and quality.

The structure of a pectin-active family 1 polysaccharide lyase from the marine bacterium Pseudoalteromonas fuliginea.

Pseudoalteromonas fuliginea sp. PS47 is a recently identified marine bacterium that has extensive enzymatic machinery to metabolize polysaccharides, including a locus that targets pectin-like substrates. This locus contains a gene (locus tag EU509_03255) that encodes a pectin-degrading lyase, called PfPL1, that belongs to polysaccharide lyase family 1 (PL1). The 2.2 Šresolution X-ray crystal structure of PfPL1 reveals the compact parallel ß-helix fold of the PL1 family. The back side of the core parallel ß-helix opposite to the active site is a meandering set of five α-helices joined by lengthy loops. A comparison of the active site with those of other PL1 enzymes suggests a catalytic mechanism that is independent of metal ions, such as Ca2+, but that substrate recognition may require metal ions. Overall, this work provides the first structural insight into a pectinase of marine origin and the first structure of a PL1 enzyme in subfamily 2.