Partial characterization of neuropathy target esterase and related phenyl valerate esterases from bovine adrenal medulla
✍ Scribed by Sogorb, M. A. ;Viniegra, S. ;Reig, J. A. ;Vilanova, E.
- Book ID
- 102876450
- Publisher
- John Wiley and Sons
- Year
- 1994
- Tongue
- English
- Weight
- 754 KB
- Volume
- 9
- Category
- Article
- ISSN
- 0887-2082
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✦ Synopsis
The mechanism by which organophosphorus-induced delayed polyneuropathy is induced relates to the specific inhibition and subsequent modification ("aging") of a protein known as neuropathy target esterase (NTE), operatively defined as paraoxon-resistant and mipafox-sensitive phenyl valerate (PV) esterase activity. This protein has fundamentally been investigated in hen brain, the latter being the habitually employed OPIDP study model. In the present article, a partial characterization is made of the NTE and other related PV esterases in the bovine adrenal medulla and brain; NTE sensitivity to the neurotoxic organophosphorus compound mipafox is investigated, and its subcellular distribution is studied. The NTE activity of the adrenal medulla was found to be the highest of those among the tissues studied to date (5000 = 1400 mU/g tissue; & SD, n = 12). This activity represented 93% of the PV esterase activity resistant to 40 p M paraoxon in the particulate fraction of the adrenal medulla and approximately 50% of total PV esterase activity. In the bovine brain, these proportions were 72 and 26%, respectively, i.e., similar to those described in hen brain. The mipafox inhibition curve of PV esterase activity resistant to 40 pM paraoxon in the particulate fraction of the adrenal medulla sug- gests that NTE activity fundamentally comprises a mipafox-sensitive component with an Iw of 6.39 p M at 30 minutes, which is similar to the value reported in hen brain. NTE activity in the bovine adrenal medulla is almost exclusively limited to the particulate fraction, the microsomal fraction, plasma membrane, and chromaffin granule-enriched fractions being the highest in terms of specific activity. On the contrary, the mitochondria-enriched fraction was very poor in such activity. In bovine brain, most NTE activity was likewise limited to the particulate fraction.