| Autor: |
Raser KJ; Department of Neuroscience Therapeutics, Parke-Davis Pharmaceutical Research Division, Warner-Lambert Company, Ann Arbor, MI 48105, USA., Buroker-Kilgore M, Wang KK |
| Jazyk: |
angličtina |
| Zdroj: |
Biochimica et biophysica acta [Biochim Biophys Acta] 1996 Jan 04; Vol. 1292 (1), pp. 9-14. |
| DOI: |
10.1016/0167-4838(95)00170-0 |
| Abstrakt: |
Human mu-calpain is activated maximally by 100-200 microM Ca2+. Both the 80 kDa and 29 kDa subunits of mu-calpain have a EF-hand type calcium-binding domain. It is known that trivalent terbium ion (Tb3+) mimics Ca2+ in many biological systems. We found that Tb3+ alone transiently activated calpain. However, in the presence of Ca2+, Tb3+ inhibited mu-calpain with an IC50 of about 100 microM. As high as 10 mM Ca2+ did not significantly shift the IC50 of Tb3+. Preincubating mu-calpain by Ca2+ (before Tb3+ and substrate were added) did not diminish the inhibition by Tb3+. On the other hand, pretreating mu-calpain with Tb3+ produced that Tb3+ has a slow dissociation rate for the calcium-binding sites when compared to Ca2+. Electrophoretic analysis revealed that terbium ion transiently activated mu-calpain followed by the aggregation of the proteinase. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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