It becomes a viscous colloidal solution in water, and is insoluble in mostly organic solvents. The degree of methyl esterification usually has a significant impact on the property of pectin. Pectin differs in composition as well as properties from diverse sources. 1, it is mostly composed of three structurally well-characterized polysaccharide motifs, the homogalacturonan (HGA), the rhamnogalacturonan I and rhamnogalacturonan II (RGI and RGII), and a small part of xylogalacturonan (XGA) (Jayani et al. Thereby, it can be divided into smooth region and hairy region (Sinitsyna et al. Generally, the natural pectin is not linear, but displays a multi-branched structure. Its side chain is mainly composed of rhamnose, arabinose, galactose, and xylose (Kohli and Gupta 2015). Pectin is acidic heteropolysaccharide linked by D-galacturonic acid via α-1,4-glycosidic bonds (C. As the by-products of juice production in the food industry, the peel and waste residues of citrus, apple, and pomelo are significant raw materials for pectin manufacturing. Generally, pectin is classified as high methoxy pectin (DE > 50%) and low-methoxy pectin (DE < 50%) (Bermúdez-Oria et al. Pectin from various sources differs in the degrees of esterification (DE). It widely exists in the cell walls of some fruits and vegetables, such as citrus, lemon, apple, and pumpkin (Vasco-Correa and Zapata Zapata 2017). Among them, pectin is a macromolecular polysaccharide with complex structure. This work is of great significance to promote our understanding of these pectin-degrading enzymes and expand the applications of these enzymes in food and industrial fields.Īccording to the American Chemical Society (ACS), pectic substances are divided into four main types, namely protopectin, pectic acid, pectinic acid and pectin (Jayani et al. Since pectin is the substrate, it is essential to discuss the salient features of its structure and property in brief. Therefore, this review aimed to clarify the origin, classification, sequence analysis, mode of action, three-dimensional structure, and catalytic mechanism of PGLs and PMGLs. However, there are still no comprehensive reviews to summarize the recent advances of PGLs and PMGLs. So far, numerous related researches have been reported (Damak et al. Notably, only two structures of PMGLs from PL1 family have been solved (PDB: 1IDJ and 1QCX), which show β-helix structure. In terms of three-dimensional structure, the current data of CAZy database shows that the PGLs of PL1, 3, and 9 families have parallel β-helix structure, the PGLs of PL2 family display (α/α) 7-barrel structure, and the PGLs of PL10 family exhibit (α/α) 3-barrel structure. Based on carbohydrate active enzymes (CAZy) database ( ), PMGLs (EC 4.2.2.10) only exist in PL1 family (Vincent et al. According to the amino acid sequence, PGLs are classified into polysaccharide lyase (PL) families 1, 2, 3, 9 and 10 (Kamijo et al. Pectin lyase and pectate lyase are also known as the polymethylgalacturonate lyase (PMGL) and polygalacturonate lyase (PGL), respectively (Jayani et al. Both can cleave the α-1, 4-glycosidic bonds by β-elimination to generate 4,5-unsaturated oligogalacturonides without producing highly toxic methanol (Saharan and Sharma 2019 Sassi et al. Of all pectinases, pectin lyase and pectate lyase have attracted great attention. depolymerized the orange peel polysaccharide into POS enzymatically, and confirmed that POS have prebiotic properties and antibacterial activity (Li et al. produced pectin-oligosaccharide from citrus by irradiation and found that POS exhibited antioxidant and anticancer effects (Kang et al. Moreover, POS exhibited various physiological activities, such as prebiotic, antibacterial, anticancer and antioxidant properties, which could be developed as functional food additives (Zhu et al. POSs could be selectively utilized by the intestinal microorganisms and were considered as the best choice for second-generation prebiotic factors (Olano-martin et al. Therefore, the enzymatic preparation of pectin oligosaccharides (POSs) with good biological activity has obtained increasing attention. Enzymatic reactions have obvious advantages such as mild reaction conditions, high specificity and degradation efficiency compared with physical and chemical methods. Pectinase can degrade pectin into oligomeric products with various physiological activities by physical degradation, chemical hydrolysis, and enzymatic preparation (Chen et al. Thus, plant pathogens attack target cells by producing cell wall-degrading enzymes, including pectinases, cellulases and proteases. Due to its rigidity and flexibility, pectin can protect the plants from invasion of pathogenic microorganism’s and mechanical injury. Pectin is a structural polysaccharide that forms the component of the primary cell wall and middle lamella of plants in fruits and vegetables (Kohli and Gupta 2015 Wu et al.
0 Comments
Leave a Reply. |