Wenyu He, Xuan Ge, Yanjun Jiang, Jian Zhang, Caoxing Huang, Yingjie Du
This paper provides a critical review of pectinases, focusing on structural diversity, advances in production technologies, industrial limitations, and emerging optimization strategies. In addition to the canonical right-handed parallel β-helix fold, several source-dependent structural features are highlighted, including Fn3-like accessory domains in bacterial enzymes, plant PME pro-domains in pectin methylesterases (PMEs), and naturally occurring bifunctional enzymes that couple de-esterification with depolymerization. Recent progress in pectinase development is also summarized, encompassing solid-state fermentation using agro-industrial residues, heterologous expression systems, protein engineering, and modern immobilization platforms, all of which contribute to improved enzyme yield, stability, and reusability. Two major industrial constraints remain prominent: the incomplete degradation of highly methyl-esterified pectin and the limited stability of enzymes under harsh operational conditions, including elevated temperature, extreme pH, solvent exposure. This review further emphasizes that effective solutions increasingly rely on multidisciplinary integration, including enzyme consortium design, bifunctional or co-expression systems enabling cascade reactions, sequence- and structure-guided engineering approaches such as directed evolution, advanced immobilization strategies, and sustainable low-cost fermentation substrates. These developments position pectinases as biocatalysts for greener and more efficient processes across food, fiber, and health-related industries.