Axonal transports of Boc-Gly-Arg-Arg-MCA hydrolysing enzyme in rat sciatic nerves.

Study on neural axon transport is a very useful method to find a neuron-specific protease. In the present study, the enzyme activity (release of 7-amino-4-methyl-coumarin from t-butyloxycarbonyl-glycyl-L-arginyl-L-arginine-4-methylcoumaryl-7-amide) was measured in the proximal, middle, and distal segments between 12 and 120 h after double ligations of rat sciatic nerves to find precursor processing enzyme specific for pair of basic amino acid residue. The enzyme activity was significantly increased not only in the proximal but also in the distal segments 12-120 h after the ligation, and the maximal enzyme activity was found in both segments at 72 h. The enzyme activity eluted by anion exchange chromatography of the proximal segment showed at least three peaks, and was slightly higher than the activity of the distal one. The activity in the middle segment was very low in comparison with the activity in the proximal and distal segments. These data indicate that some of the enzymes specific for pair of basic amino acid residue are transported by both anterograde and retrograde axonal flow, and may undergo a neuron-specific processing.