SsoPox

SsoPox is an enzyme in the phosphotriesterase-like lactonase family that originates from the hyperthermophilic archaeon Sulfolobus solfataricus P2. It is a thermostable metalloenzyme that catalyzes the hydrolysis of both lactones and organophosphate esters, with paraoxon among its substrates. Its broad and promiscuous substrate range has made it a focus of research as a robust biocatalyst and a model system for enzyme evolution.

Structurally, SsoPox features a binuclear metal center coordinated by conserved residues that activate a water molecule for nucleophilic attack on the substrate. The active-site pocket can accommodate diverse substrates, contributing to its catalytic versatility. The enzyme is noted for high thermal stability, retaining activity at elevated temperatures and under challenging conditions, which supports laboratory and potential industrial use. Through directed evolution and rational design, researchers have created variants with shifted or enhanced substrate specificity and improved catalytic efficiency toward particular organophosphates or lactones.

Applications and research areas include environmental detoxification of organophosphate pollutants and the use of SsoPox as a robust biocatalyst in synthetic chemistry. It also serves as a model system for studying enzyme promiscuity, structure–function relationships, and the adaptability of the paraoxonase-related enzyme family. In some studies, engineered variants have been explored for broader detoxification capabilities and resilience in real-world conditions.

Discovery and naming: the enzyme was identified from the genome of Sulfolobus solfataricus and named to reflect its origin and functional class. Structural and biochemical studies have clarified details of its metal center, substrate interactions, and thermostability.

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