Proteoglycans of pig colon connective tissue

Connective tissue disorders involving the gastrointestinal tract wall are diverse yet the molecular composition of these tissues is little understood. Here we isolate and characterize proteoglycan from normal colon wall of pig. Proteoglycans were extracted under dissociative conditions (4M GuCl) and fractionated by ion-exchange and gel-filtration chromatographies and density gradient centrifugation. Two major proteoglycans were obtained. One, of high density, consists mainly of chondroitin sulphate with some dermatan sulphate and heparin or heparan sulphate bound to 14% protein with high aspartic acid, glutamic acid, glycine and serine contents. This resembles the 'large' proteoglycans of articular cartilage, sclera and skin. The other, of low density, contained dermatan sulphate and 34% protein rich in aspartic acid, glutamic acid and leucine. This resembles the 'small' proteoglycans of cervical, nasal septal, skin and scleral origins. Total proteoglycan content of the tissue is low; < 0.1% of dry weight.