Partial purification and characterization of amidase from human and mouse serum

The murein hydrolases of Escherichia coli: properties, functions and impact on the course of infections in vivo

“…The amide bond between the carboxyl group of the lactyl moiety of muramic acid and the cc-amino group of the first amino acid of the stem peptide, L-alanine, is cleaved by an amidase. N-Acetylmuramyl-L-alanine amidases are found widely among bacteria and are also present in mammalian sera (Valinger et al, 1982). The enzyme isolated from E. coli (van Heijenoort & van Heijenoort, 1971 ;van Heijenoort et al, 1975) does not accept whole sacculi as a substrate but acts on muropeptides, a finding similar to that for the fl-N-acetylglucosaminidase.…”

Peptidoglycan Signaling in Innate Immunity and Inflammatory Disease

“…1). This specificity is identical to the PGN degradation enzyme, serum N-acetylmuramoyl-L-alanine amidase, leading investigators to conclude that they are the same enzyme (15,16). Mammalian PGRPs also have distinct expression patterns, with PGRP-S found in polymorphonuclear leukocytes and bone marrow, PGRP-I␣ and PGRP-I␤ found in the esophagus, and PGRP-L expressed in the liver, suggesting that they each may play a unique role in host defense.…”

Innate Immune Responses in Peptidoglycan Recognition Protein L-Deficient Mice

“…However, human serum amidase, which circulates in blood at 100 g/ml, has the same 15 N-terminal amino acids as PGRP-L (2) and the same biological activity (35). Similarly, mouse PGRP-L possesses amidase activity, which was first identified in blood (4,34), raising the possibility that PGRP-L may be a soluble secreted serum protein in vivo. A Myc epitope-tagged murine PGRP-L was created and introduced into HEK 293 cells.…”