Sjödin L, Brodin E, Nilsson G, Conlon T P
Acta Physiol Scand. 1980 May;109(1):97-105. doi: 10.1111/j.1748-1716.1980.tb06570.x.
Tyr8-SP has been radioactively labeled with 125I to a specific activity of 200 microCI/microgram. This tracer has been found to be rapidly and reversibly bound in a specific way to dispersed pancreatic acinar cells. The specific binding is saturable and dependent on incubation temperature. At 37 degrees C 125I-tyr8-SP is bound to a less degree than at lower temperatures since the peptide is rapidly degraded at 37 degrees C. Native SP inhibits binding of tracer. Results have been analyzed according to Scatchard and suggest 2 functionally distinct types of binding sites; a small number of sites with high affinity and a larger number of sites with low affinity for SP. SP-sites also bind eledoisin and physalaemin which are peptides similar to SP in terms of chemical structure and biological activities. The concentration range in which SP, physalaemin, nd eledoisin inhibit binding of 125I-tyr8-SP correlates well with the range in which these peptides stimulate biochemical processes like outflux of 45Ca, accumulation of cyclic GMP and release of amylase from acinar cells.
酪氨酸8-速激肽已用125I进行放射性标记，比活度为200微居里/微克。已发现这种示踪剂能以一种特定方式快速且可逆地与分散的胰腺腺泡细胞结合。特异性结合是可饱和的，且依赖于孵育温度。在37℃时，125I-酪氨酸8-速激肽的结合程度低于较低温度时，因为该肽在37℃时会快速降解。天然速激肽会抑制示踪剂的结合。根据斯卡查德分析法对结果进行了分析，结果表明存在两种功能不同的结合位点类型；少量高亲和力位点和大量低亲和力位点。速激肽位点也能结合蛙皮素和雨蛙肽，这两种肽在化学结构和生物活性方面与速激肽相似。速激肽、雨蛙肽和蛙皮素抑制125I-酪氨酸8-速激肽结合的浓度范围与这些肽刺激生化过程（如45Ca外流、环鸟苷酸积累和腺泡细胞淀粉酶释放）的浓度范围密切相关。
