Treatment with dimethyl suberimidate, a cross-linking bifunctional agent, showed that Sm1 and Sm2 nucleases of Serratia marcescens B10M1 are polydisperse in solution and consist of monomers and dimers at the level of pH optimal for the enzyme activity. The data suggest that nucleases from the strain B10M1 and any other strain are polydisperse at pH optimum if their amino acid sequences are identical
