Sulphur containing bond is not found in

Hyaluronic Acid A sulfate-free mucopolysaccharide. It was first isolated from the vitreous humor of the eye. Later it was found to be present in synol fluid, skin, umbilical cord, haemolytic streptococci and in the rheumatic nodule. It occurs both free and salt-like combination with proteins and forms so-called ground substance of mesenchyme, an integral pa of the gel-like ground substance of connective and other tissues. Composition: It is composed of repeating units of N-acetyl glucosamine and D-Glucuronic acid. On hydrolysis, it yields equimolecular quantities of D-Glucosamine, D-Glucoronic acid and acetic acid (Fig. 3.20). Functions: (See below under proteoglycans) Hyaluronidase: An enzyme present in ceain tissues, notably testicular tissue and spleen, as well as in several types of pneumococci and haemolytic streptococci. The enzyme catalyzes the depolymerization of hyaluronic acid and by reducing its viscosity facilitates diffusion of materials into tissue spaces. Hence the enzyme, sometimes, is designated as spreading factor.Ref: Textbook of medical biochemistry, MN Chatterji, 8th edition, page no: 34