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A comparison of solubilized and membrane bound forms of choline-O-acetyltransferase (EC 2.3.1.6) in mouse brain nerve endings
| Content Provider | Semantic Scholar |
|---|---|
| Author | Smith, Craig P. Carroll, Paul T. |
| Copyright Year | 1980 |
| Abstract | Abstract Mouse brain choline-O-acetyltransferase (EC 2.3.1.6) (ChAT) activity was studied in vitro using a 100 mM sodium phosphate buffer (pH 7.4) wash of a crude vesicular fraction containing solubilized ChAT and a washed crude vesicular fraction containing membrane bound ChAT. Both the solubilized and membrane bound forms of ChAT acetylate choline linearly for 30 min. High concentrations of acetylcholine (ACh) inhibit solubilized ChAT to a greater degree than the membrane bound enzyme form. Forty per cent of the ACh synthesized by membrane bound ChAT survives hydrolysis in the presence of excess acetylcholinesterase (AChE), whereas almost none of of the ACh synthesized by the solubilized enzyme form does. Solubilized ChAT is significantly more inhibited by 4-(1-napthylvinyl)pyridine (4-NVP) either in vivo or in vitro than the membrane bound enzyme form. The activity of solubilized ChAT is increased as the sodium concentration is increased from 236 mM to 318 mM whereas the activity of the membrane bound form is not. Membrane bound ChAT has both a high ( K m = 3.2 μM ) and a low ( K m = 0.48mM ) affinity Michaelis constant as a function of added choline when velocity values are not corrected for acetylation of endogenous choline. Upon correction, only a low affinity Michaelis constant ( K m = 0.27mM ) is obtained for the membrane bound enzyme form similar to that of solubilized ChAT ( K m = 0.19mM ). The results suggest that a membrane bound form of ChAT exists in mouse brain. |
| Starting Page | 363 |
| Ending Page | 371 |
| Page Count | 9 |
| File Format | PDF HTM / HTML |
| DOI | 10.1016/0006-8993(80)91074-4 |
| PubMed reference number | 7357434 |
| Journal | Medline |
| Volume Number | 185 |
| Alternate Webpage(s) | https://api.elsevier.com/content/article/pii/0006899380910744 |
| Alternate Webpage(s) | https://www.sciencedirect.com/science/article/pii/0006899380910744?dgcid=api_sd_search-api-endpoint |
| Alternate Webpage(s) | https://doi.org/10.1016/0006-8993%2880%2991074-4 |
| Journal | Brain Research |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
