Lysozyme in Epiphyseal Cartilage

Abstract

The localization of chick embryonic lysozyme was determined by two techniques : by studying the rate of release from the tissue during sequential enzymatic digestion and by immunocytochemistry . Both techniques indicate that, in this tissue, lysozyme is primarily extracellular . Cartilage lysozyme was isolated and partially characterized and found to be identical with egg white lysozyme in its immunologic and enzymatic behavior . In addition, a method for the isolation of large numbers of viable chondrocytes is described .As a further step in the study of the role of lysozyme in cartilage, a series of experiments on intact cartilage and isolated chondrocytes from chick embryos was undertaken to determine its precise distribution as well as to partly characterize it . We here report data from this study indicating that over 99% of chick embryonic cartilage lysozyme is extracellular. In addition, certain properties of cartilage lysozyme, including its immunologic identity with hen's egg white lysozyme, are described as well as a digestion procedure for the isolation of chondrocytes in sufficient numbers for biochemical assays .

The distribution of muramidase (lysozyme) in human tissues.

“…In all these studies muramidase was found to be extracellular. Kuettner et al (1971), using an immunofluorescent technique, showed localization around chondrocyte lacunae, an appearance similar to the D. Y. Mason and C. R. Taylor pattern which we encountered in human cartilage.…”

“…However, Klockars and Osserman (1974) discovered an apparent species difference in that rat lacrimal tissue was devoid of this enzyme. CARTILAGE Muramidase has been detected in chick and human rat cartilage (Kuettner, Eisenstein, Soble, and Arsenis, 1971;Greenwald and Sajdera, 1971;Greenwald, Josephson, Diamond, and Tang, 1972). In all these studies muramidase was found to be extracellular.…”

Identification of neutral proteases in human neutrophil granules that degrade articular cartilage proteoglycan

“…A lysozyme is present in cartilage matrix in the extracellular space (25)(26)(27) and possesses the ability to form complexes with the proteoglycan subunit of cartilage (28). It has been suggested that the function of cartilage lysozyme is related to its interaction with oligosaccharides in the matrix (26) or in the anabolic metabolism of the tissue (28), a possibility indicating that the role of cartilage lysozyme may be quite different from that of the degradative leukocyte lysozyme.…”

Isolation and characterization of two glycoproteins from hyaline cartilage

“…In addition to the link proteins which stabilize the proteoglycan -hyaluronate complexes [l], several other non-collagenous proteins have so far been identified, the possible biological role of very few having been proposed from data of in vitro experiments [2]. These include various enzymes [3 -51, enzyme inhibitors [6-81, lysozyme [9], a 54-kDa protein that binds to collagen and in combination with proteoglycans affects in vitro the diameter of collagen type I1 fibrils [lo], the C-propeptide of type I1 collagen (chondrocalcin) [l I] which upon reduction gives rise to two 35-kDa polypeptides and may have a role in the calcification of cartilage matrix [12]. Other examples are the 400-kDa protein (an oligomer of a 116-kDa protein [13]) and other 'matrix proteins' isolated and characterized by Heineg5rd and his group, protein of 148 kDa [14], 36 kDa [14] (which seems to promote chondrocyte attachment [15]) and 58 kDa and a 59-kDa glycoprotein [16], called fibromodulin because it modulates collagen fibrils [I 71.…”