ISSN:
1471-4159
Quelle:
Blackwell Publishing Journal Backfiles 1879-2005
Thema:
Medizin
Notizen:
Abstract: Following incubation of [3H]dynorphin A (1–8) and [3H]dynorphin A (1–9) with suspensions of guinea pig brain membranes, analysis of the supernatants by HPLC has shown that both peptides are degraded at 25°C and at 0°C. Bestatin and captopril reduce degradation at 0°C but for a similar degree of protection at 25°C argininecontaining dipeptides are also required. The effects of these peptidase inhibitors on the degradation profiles indicate that [3H]dynorphin A (1–8) has three main sites of cleavage: the Tyr1-Gly2, Arg6-Arg7, and Leu5-Arg6 bonds. With [3H]dynorphin A (1–9) as substrate the Arg7-Ile8 and Ile8-Arg9 bonds are also liable to cleavage. In binding assays, in contrast to the effects of peptidase inhibitors on the degradation of unbound [3H]dynorphin A (1–8) and [3H]dynorphin A (1–9), bestatin and captopril have little effect on the binding characteristics of the tritiated dynorphin A fragments at the k-site at 0°C. However, at 25°C binding is low in the absence of peptidase inhibitors. When binding at μ- and δ-sites is prevented, the maximal binding capacities of [3H]dynorphin A (1–8), [3H]dynorphin A (1–9), and [3H](–)-bremazocine at the k-site are similar; [3H]dynorphin A (1–9) has 5–10 times higher affinity for the k-site than [3H]dynorphin A (1–8). Comparison of the effects of peptidase inhibitors on unbound dynorphin A fragments with their effects in binding assays suggests that the bound peptides are protected from the action of peptidases.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1111/j.1471-4159.1985.tb05520.x
