Abstract
The collagenase produced by rat uterine cells in culture has been examined for its ability to degrade denatured collagen. Acting as a gelatinase, rat uterus collagenase was able to successfully degrade the denatured chains of collagen types I through V. In addition, the enzyme produced multiple cleavages in these chains and displayed values for Km of 4-5 microM, compared to values of 1-2 microM when native collagen was used as substrate. Furthermore, rat uterus collagenase degraded the alpha 2 chain of denatured type I collagen at a significantly faster rate than the alpha 1 chain, as previously observed for human skin fibroblast collagenase. In contrast to the action of human skin collagenase, however, the rat uterus enzyme was found to be a markedly better gelatinase than a collagenase, degrading the alpha chains of denatured type I guinea pig skin collagen at rates some 7-15-fold greater than native collagen. Human skin collagenase degrades the same denatured chains at rates ranging from 13-44% of its rate on native collagen. Rat uterus collagenase, then, is approximately 50 times better a gelatinase than is human skin collagenase. In addition to its ability to cleave denatured collagen chains at greater rates than native collagen, the rat uterus collagenase also attacked a wider spectrum of peptide bonds in gelatin than does human skin collagenase. In addition to cleaving the Gly-Leu and Gly-Ile bonds characteristic of its action on native collagen, rat uterus collagenase readily catalyzed the cleavage of Gly-Phe bonds in gelatin. The rat enzyme was also capable of cleaving Gly-Ala and Gly-Val bonds, although these bonds were somewhat less preferred by the enzyme. The cleavage of peptide bonds other than Gly-Leu and Gly-Ile appears to be a property of the collagenase itself and not a contaminating protease. Thus, it appears that the collagenase responsible for the degradation of collagen during the massive involution of the uterus might also act as a gelatinase to further degrade the initial products of collagenolysis to small peptides suitable for further metabolism.
Highlights
The collagenaseproduced byrat uterine cells in culture has been examined for its ability to degrade denatured Collagen
In addition to itsability to cleave denatured collagen chains at greater rates than native collagen, the rat uterus collagenase attacked a wider spectrum of peptide bonds in gelatin than does human skin collagenase
In addition to cleaving the Gly-Leu and GlyIle bonds characteristic of its action on native collagen, rat uterus collagenase readily catalyzed the cleavage of Gly-Phe bonds in gelatin
Summary
In addition to itsability to cleave denatured collagen chains at greater rates than native collagen, the rat uterus collagenase attacked a wider spectrum of peptide bonds in gelatin than does human skin collagenase. Studies on the substrate specificity of the uterine enzyme using monomeric collagen have indicated the existence of marked differences in catalytic function as compared to skin fibroblast collagenase (4, 16) While both enzymes degrade collagen types 1-111, the skin protease cleaves each substrate molecule at extremely disparate rates, whereas the uterine enzyme exhibits virtually no preference with respect to collagen type. It is widely believed that following the initial 3/41/4 cleavage in collagen, degradation of the resultantdenatured peptides is accomplishedby noncollagenolytic proteases, such as connective tissue gelatinases (9-11) This present report examines the gelatinolytic activity of rat uterus collagenase. The dataindicate that the uterine enzyme cleaves gelatin much faster than it attacks native collagen and possesses far greater activity against the denatured substratethan has been observed for any collagenase to date
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