An enzyme derived from a bacterium Proteus vulgaris, and which has recently been found to help with the regeneration of the spinal cord after it has been severed.

Once the nerves of the spine have been damaged, the damage site is quickly covered with scar tissue by the surrounding glial cells multiplying into it. This prevents the severed nerve being able to re-cross the scar barrier and join the other side.

One of the components of the scar tissue is chondroitin sulfate proteoglycan (CSPG), whose carbohydrate branches the enzyme chondroitinase ABC is able to 'prune'. It has therefore been dubbed a molecular machete.

Experiments on rats have shown that they have regained the ability to walk, but not any feeling, after treatment with this. It is therefore not a miracle cure yet, but there is hope it may be used as part of a cocktail of treatments for nerve regeneration. The latest experiments, at King's College London by a team led by Elizabeth Bradbury, were published in this week's Nature.

The 'ABC' part is because the chondroitin sulfate comes in three isomeric forms, labelled ChS-A, ChS-B, and ChS-C, and the enzyme is able to cleave all three.