A substantially pure modified heparinase III comprising: a polypeptide having the amino acid sequence of the mature peptide of SEQ ID NO: 2, wherein at least one histidine residue selected from the group consisting of His36, His105, His110, His139, His152 , His225, His234, His241, His424, His469 and His539 has been replaced with a residue selected from the group consisting of alanine, serine, tyrosine, threonine and lysine.Una heparinasa III modificada, sustancialmente pura, que comprende: un polipéptido que tiene la secuencia de aminoácidos del péptido maduro de SEQ ID NO: 2, en donde al menos un residuo histidina seleccionado del grupo consistente en His36, His105, His110, His139, His152, His225, His234, His241, His424, His469 e His539 ha sido sustituido con un residuo seleccionado del grupo que consiste en alanina, serina, tirosina, treonina y lisina.
