Partial glyceride lipase with unique glyceride specificity: Its origin, classification, structural features,...

Partial glyceride lipase (PGL) is one kind of lipase with special substrate-catalyzing properties, which can solely act on monoacylglycerols or monoacylglycerols and diacylglycerols, rather than triacylglycerols. PGL plays a crucial role in the survival and development of animals, plants and microorganisms, and also has great application value in industry. Here, the origin, classification, structural features, enzymatic and catalytic properties, as well as application potential of PGL are systematically reviewed for the first time. Based on a comprehensive analysis of relevant studies in recent years, we conclude that the exceptional substrate specificity of PGL is mainly attributed to the lid and catalytic pocket. PGL's catalytic pocket features a characteristically narrow geometry, with an overhanging "bridge-like" structural motif that sterically hinders the entry of bulkier substrates, such as triacylglycerols. Owing to these properties, PGL exhibits great potential in high-purity functional oil production, healthcare, and organic synthesis. However, currently discovered types of PGL are limited. As of the submission of this manuscript, only approximately 20 characterized PGLs have been included in the Uniprot and NCBI databases. Existing studies and theoretical frameworks remain fragmented, hindering practitioners from extracting effective and actionable information for industrial production. This paper can provide systematic theoretical support for the molecular modification, industrial application, and exploration of novel PGL variants.