MUCOLYTIC ENZYMES 



strain of C. welchii, and in extracts of spleen and ciliary body (29). 

 Chain and Duthie (6) made the important observation that purified 

 testis extracts, which contained in liigh concentrations the "spreading 

 factor" of Duran-Reynals (8) and of McClean (19), also contained 

 hyaluronidase; in fact, they proposed that hyaluronidase was identical 

 with the "spreading factor." Based on the findings of Chain and 

 Duthie, an intensive study was made of the hyaluronic acid-hyal- 

 uronidase system by a number of investigators. 



Hyaluronidase and spreading factor have been found in extracts 

 of leach heads, in a number of snake and other venoms, in skin, in 

 staphylococci, and in many other microorganisms. Aside from some 

 unspecific spreading factors, which may act by oxidatively depolymer- 

 izing hyaluronic acid, the identity of hyaluronidase with spreading 

 factor seems well established. The only exception still is the occur- 

 rence of a strong spreading reaction in extracts or filtrates of some group 

 A hemolytic streptococci in which no hyaluronidase could be de- 

 tected (27). 



In the spreading reaction, extracts are injected intradermally in 

 rabbits along with a suitable indicator such as certain dyes, hemo- 

 globin, bacterial toxins, or India ink. In the presence of spreading 

 factor, these indicators difTuse over an area of the skin proportional 

 to the concentration of agent, while in the controls the injected indicator 

 remains localized in a small bleb. The reaction apparently is caused 

 by the depolymerization of a hyaluronic acid gel present in the inter- 

 cellular substance of the dermis. Increased capillary permeability is 

 not caused by hyaluronidase. Obviously the capillary endothelial 

 cement does not contain hyaluronic acid. The spreading reaction can 

 also be demonstrated in the cornea (unpublished work), apparently 

 acting by the depolymerization of the monosulfuric acid ester of 

 hyaluronic acid, which occurs in the substantia propria (24). 



Hyaluronic acid, a polymer of acetylglucosamine and glucuronic 

 acid, occurs in different tissues in polydisperse form. Its molecular 

 weight has been estimated from its double refraction of flow as between 

 200,000 and 400,000 (5), a figure which may be considerably higher 

 when measured on material derived from quite solid gels, as from some 

 malignant cysts or from the nucleus pulposus. 



Three methods are available for the quantitative estimation of 

 hyaluronidase and they depend upon: (a) the hydrolysis of the gluco- 



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