Forget G, Heisler S, Park W K, Sirois P, Gagnon D, Regoli D
J Pharm Pharmacol. 1975 Jul;27(7):491-6. doi: 10.1111/j.2042-7158.1975.tb09490.x.
The coupling of fluorescamine (4-phenylspiro[furan-2(3H), 1'-PHTHALAN]-3,3'dione) to angiotensin II to form a fluorescent derivative was studied. Complete reaction of the peptide below concentrations of 10- minus 4 M could be achieved with a fluorescamine concentration of 0-3 mg ml- minus 1 of acetone at pH 8-3, and the lowest concentration detectable by fluorescence spectroscopy was 100 pmol ml- minus 1. The derivative, as prepared did not react with ninhydrin, and no fluorescence was generated when fluorescamine was reacted with (1-Sar)-ATII. These data suggest that fluorescence is generated only through the coupling of fluorescamine to the N-terminal primary amine of ATII. The ATII-fluorescamine derivative has the same intrinsic activity on the contraction of rat colon (elevenfold loss of affinity), and on the release of fluorogenic corticosteroids from bovine adrenal cortical slices (sixfold loss of affinity) compared to ATII. Water-hydrolysed fluorescamine and Asp-fluorescamine did not contract rat colon preparations; the contractile response to ATII-fluorescamine was blocked by (8-Leu)-ATII, a specific ATII antagonist. These findings suggest that theATII fluorophore shares a common receptor site with the native octapeptide. The rate loss of biological activity of the ATII-fluorescamine derivative was appreciably lower than that observed for ATII. The present study suggests that the ATII-fluorescamine derivative can be substituted for radioactively-labelled ATII for use in a variety of applications.
研究了荧光胺（4-苯基螺[呋喃-2(3H),1'-苯酞]-3,3'-二酮）与血管紧张素II偶联形成荧光衍生物的过程。在pH 8.3的条件下，荧光胺浓度为0.3 mg/ml丙酮，肽浓度低于10⁻⁴ M时可实现完全反应，荧光光谱可检测到的最低浓度为100 pmol/ml。所制备的衍生物与茚三酮不反应，荧光胺与(1-Sar)-ATII反应时也不产生荧光。这些数据表明，荧光仅通过荧光胺与ATII的N端伯胺偶联产生。与ATII相比，ATII-荧光胺衍生物对大鼠结肠收缩（亲和力损失11倍）和牛肾上腺皮质切片中荧光皮质类固醇释放（亲和力损失6倍）具有相同的内在活性。水水解荧光胺和天冬氨酸-荧光胺不会使大鼠结肠制剂收缩；对ATII-荧光胺的收缩反应被特异性ATII拮抗剂(8-Leu)-ATII阻断。这些发现表明，ATII荧光团与天然八肽共享一个共同的受体位点。ATII-荧光胺衍生物生物活性的丧失速率明显低于ATII。本研究表明，ATII-荧光胺衍生物可替代放射性标记的ATII用于各种应用。
