The invention relates to rationally designed polysaccharide lyases and uses thereof. In particular, the invention relates to modified chondroitinase B. The modified chondroitinase B enzymes of the invention are useful for a variety of purposes, including cleaving and sequencing polysaccharides such as glycosaminoglycans (GAGs) as well as removing polysaccharides from a solution. The invention also includes methods of inhibiting anticoagulant activity, inhibiting angiogenesis, treating cancer, and inhibiting maternal malarial infection.