Advances in Carrageenases: Molecular Engineering, Immobilization Techniques, and Biomedical Potential of Carrageenan Oligosaccharides

Carrageenan is a sulfated polysaccharide extracted from red algae, widely utilized in the food and pharmaceutical industries due to its unique gelling properties and biological activities. However, its high molecular weight and low solubility limit certain high-value applications. Carrageenases specifically degrade carrageenan to produce low-molecular-weight oligosaccharides with excellent bioactivities, thereby overcoming this bottleneck. This review systematically summarizes the microbial sources of carrageenases and the classification characteristics of their three types (κ, ι, and λ) within the GH16, GH82, and GH150 families. Furthermore, it highlights recent advances in molecular engineering strategies, including site-directed mutagenesis and non-catalytic domain fusion, as well as enzyme immobilization techniques utilizing carriers such as magnetic nanoparticles and metal–organic frameworks, which significantly enhance thermostability, catalytic efficiency, and reusability. Additionally, the potential applications of carrageenan oligosaccharides in biomedical fields, including antioxidant, immunomodulatory, antitumor, and anti-inflammatory activities, are thoroughly discussed. This review provides a theoretical reference for the rational design and industrial application of carrageenases, while also offering new insights for the high-value development of algal resources.