The present invention provides new biopolymers which mimic the properties of natural polysaccharides found in vivo. The inventive polysaccharides can be used as viscosupplements, viscoelastics, tissue space fillers, and/or anti-adhesive agents. Also provided are pharmaceutical compositions comprising the inventive polymers and methods of using them including, for example, in the treatment of arthritic and sport-injured knee joints; in reconstruction or cosmetic procedures, intervertebral disc repair, treatment of vocal cord problems, treatment of urinary incontinence, and prevention of adhesion formation following abdominal or gynecological surgery.