Acid proteases from species of Mucor. III. Interaction with concanavalin A and concanavalin A Sepharose
The reaction of Mucor miehei protease with concanavalin A was followed by a turbidimetric assay in the pH range 5–8. At pH 4.0, no turbidity developed but binding of the enzyme to concanavalin A could be demonstrated by gel filtration. Two fractions of apparent molecular weight 65 000 and 52 000 were isolated, the 65 000 molecular weight species apparently representing a protomer of concanavalin A (24 000) bound to the enzyme. An analysis of the circular dichroism spectrum of this complex suggested that protomer binding results in a conformational change in the enzyme which is associated with a 30% increase in proteolytic activity.At pH 6.0, the enzyme was strongly bound to columns of concanavalin A Sepharose but could be removed by including α-methyl D-glucoside and NaCl in the elution buffer. Some column degradation occurred at room temperature but was not detectable at 4 °C where rapid elution of the enzyme resulted in a greater than 90% yield of highly active protein. Periodate-oxidized Mucor miehei protease and Mucor rennin did not react with concanavalin A and were not bound to the affinity column.