Catalysis of the specific cleavage of the beta-(1->4) glycosidic linkage between N-acetylmuramyl and N-acetylglucosaminyl residues in peptidoglycan, with the concomitant formation of 1,6-anhydro-N-acetylmuramyl residues. Acts on linkages within peptidoglycan chains (i.e. not at the ends) to produce shorter strands with 1,6-anhydromuramic acid ends.

Catalysis of the specific cleavage of the beta-(1->4) glycosidic linkage between N-acetylmuramyl and N-acetylglucosaminyl residues in peptidoglycan, with the concomitant formation of 1,6-anhydro-N-acetylmuramyl residues.

Catalysis of a biochemical reaction at physiological temperatures. In biologically catalyzed reactions, the reactants are known as substrates, and the catalysts are naturally occurring macromolecular substances known as enzymes. Enzymes possess specific binding sites for substrates, and are usually composed wholly or largely of protein, but RNA that has catalytic activity (ribozyme) is often also regarded as enzymatic.