2 DISTINCT CHONDROITIN SULFATE ABC LYASES - AN ENDOELIMINASE YIELDINGTETRASACCHARIDES AND AN EXOELIMINASE PREFERENTIALLY ACTING ON OLIGOSACCHARIDES

Crude enzyme obtained from chondroitin sulfate-induced Proteus vulgari s NCTC 4636 has been fractionated into 1) an endoeliminase capable of depolymerizing chondroitin sulfate and related polysaccharides to prod uce, as end products, a mixture of Delta(4)-unsaturated tetra- and dis accharides and 2) an exoeliminase preferentially acting on chondroitin sulfate tetra- and hexasaccharides to yield the respective disacchari des. Isolation of the two enzymes was achieved by a simple two-step pr ocedure: extracting the enzymes from intact P. vulgaris cells with a b uffer solution of nonionic surfactant and then treating the extract by cation-exchange chromatography. Each of the enzymes thus prepared was apparently homogeneous as assessed by SDS-polyacrylamide gel electrop horesis and readily crystallized from polyethylene glycol solutions. B oth enzymes acted on various substrates such as chondroitin sulfate, c hondroitin sulfate proteoglycan, and dermatan sulfate at high, but sig nificantly different, initial rates. They also attacked hyaluronan but at far lower rates and were inactive to keratan sulfate, heparan sulf ate, and heparin. Our results show that the known ability of the conve ntional enzyme called ''chondroitinase ABC'' to catalyze the complete depolymerization of chondroitin sulfates to unsaturated disaccharides may actually result from the combination reactions by endoeliminase (c hondroitin sulfate ABC endolyase) and exoeliminase (chondroitin sulfat e ABC exolyase).