Anterograde axonal transport of Boc-Arg-Val-Arg-Arg-MCA hydrolyzing enzyme in rat sciatic nerves: cleavage occurs between basic residues.
Axonal transport of Boc-Arg-Val-Arg-Arg-MCA hydrolyzing enzyme activity was studied in rat sciatic nerves from 12 to 120 h after double ligations. The anterograde axonal transport increased and peaked 72 h after ligation. The optimum pH for Boc-Arg-Val-Arg-Arg-MCA hydrolyzing enzyme activity was 6.5 to 6.9 and did not require Ca(2+) for the activity. Two molecular forms with enzyme activity were identified by size-exclusion chromatography and the molecular masses of the two enzymes were estimated to be 98 and 52 kDa. Two enzyme activities were strongly inhibited by Hg(2+), Cu(2+) and trypsin inhibitors such as TLCK, antipain and leupeptin. It cleaved the substrate, Boc-Arg-Val-Arg-Arg-MCA, between the dibasic sequence Arg-Arg, and needed a support of aminopeptidase B-like enzyme activity for the liberation of 7-amino-4-methylcoumarin. These results suggest that the enzyme is transported in rat sciatic nerves and involved in the post-translational processing of precursor proteins under the anterograde axonal transport. But there is absolutely no evidence for a role in precursor processing and such a putative role is purely speculative.
Imaizumi
T
T
Department of Pharmaceutical Analytical Chemistry, Showa College of Pharmaceutical Sciences, Machida-shi, 3-3165 Higashi-tamagawagakuen, Tokyo, Japan.
Jyonouchi
K
K
Kato
T
T
Chikuma
T
T
Tanaka
A
A
D000818:Animals; D001370:Axonal Transport; D004789:Enzyme Activation; D006868:Hydrolysis; D008297:Male; D008666:Metalloendopeptidases / Q000737:chemistry / Q000378:metabolism*; D009842:Oligopeptides / Q000737:chemistry / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012584:Sciatic Nerve / Q000378:metabolism*
D009842:Oligopeptides; C409671:Boc-Arg-Val-Arg-Arg-MCA hydrolyzing enzyme; D008666:Metalloendopeptidases