Description:
<jats:title>Abstract</jats:title><jats:p>Tritium labeling of the mast cell degranulating substance P analog H‐Arg‐Pro‐Lys(3,4‐<jats:sup>3</jats:sup>H‐Pro)‐NH‐C<jats:sub>12</jats:sub>H<jats:sub>25</jats:sub> by catalytic saturation of the dehydroproline (Dhp<jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="#note1" /><jats:fn><jats:p>Abbreviations: Ac, acetyl; Dhp, L‐3,4‐dehydroproline; DMA, dimethyl‐acetamide; DMF, dimethylformamide; HOBt, 1‐hydroxybenzotriazole; MA, mixed anhydride coupling; NMM, N‐methylmorpholine; ONSu, N‐hydroxysuccinimide ester; TEA, triethylamine.</jats:p></jats:fn>
) double bond is described. Catalytic tritiation in water afforded the radioactive analog with a specific activity of 1.07 TBq/mmol. Tenfold enhancement of the catalyst‐to‐substrate ratio resulted in a reduced specific activity of 0.74 TBq/mmol.</jats:p>