Publisher Summary This chapter discusses the synthesis of bacterial alginate lyase. The enzyme occurs in an organism isolated from Potomac Bay mud capable of utilizing alginic acid as a sole carbon source. The organism was classified as a pseudomonad 1 and can be obtained from the American Type Culture Collection. The assay is based on the formation of compounds giving rise to β-formylpyruvic acid when subjected to periodate oxidation. Both 4-deoxy-5-ketouronic acid and the unsaturated uronic acid moiety of the intermediate oligosaccharides are cleaved by periodate to form β-formylpyruvate, whereas intact alginie acid does not so react. Thus, aliquots of the described incubation mixture are assayed with thiobarbituric acid according to the modification of Weissbach and Hurwitz. Another convenient assay would be the measurement of increased absorption at 230 mμ because of the formation of the unsaturated uronic acid portion of the intermediate oligosaccharides. The final monosaccharide end product, the ketodeoxyuronic acid, is not measured in this assay. The reagents used, procedure followed, and the steps involved in the purification are also described in the chapter.