STUDIES ON THE ALGINASE OF AGARBACTERIUM ALGINICUM

Abstract

Cell-free extracts prepared from alginate-grown Agarbacterium alginicum were observed to hydrolyze sodium alginate to its constituent monosaccharide residues. The enzyme was found to be relatively heat stable at pH 7 and only 40% of its activity was lost when it was heated for 5 minutes at 100 °C. The enzyme was active over a pH range of 5–10 with the optimum at pH 7. The optimum temperature was 37–40 °C and little activity was observed below 20 °C or above 55 °C. Among the compounds tested, only sodium alginate could serve as substrate for the enzyme.Enzymatic activity of the extract was enhanced by several monovalent cations but not by divalent cations. Those monovalent cations found to be effective were ammonium, lithium, potassium, and sodium. The trivalent anions, arsenate and phosphate, also produced increased activity when added to the extract. Since low concentrations of p-chloromercuribenzoate and N-ethyl maleimide were inhibitory while cysteine, glutathione, or 2-mercaptoethanol reversed the inhibition and increased the activity, sulphydryl dependency was indicated.A 10-fold purification of alginase was attained by removal of nucleic acid and inactive protein by precipitation with protamine sulphate and acetic acid. Further purification was not achieved.