@article{oai:repo.qst.go.jp:00046745,
 author = {Hanyu, Masayuki and Takada, Yuuki and Hashimoto, Hiroki and Kawamura, Kazunori and Zhang, Ming-Rong and Fukumura, Toshimitsu and 破入 正行 and 高田 由貴 and 橋本 裕輝 and 河村 和紀 and 張 明栄 and 福村 利光},
 issue = {10},
 journal = {Journal of Peptide Science},
 month = {Aug},
 note = {A procedure for the synthesis of a11C-labeled oligopeptide containing [1-11C]1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid
([1-11C]Tpi) from the corresponding Trp•HCl-containing peptides has been developed involving a Pictet-Spengler reaction
with [11C]formaldehyde. The synthesis of [1-11C]Tpi from Trp and [11C]formaldehyde was examined as a model reaction with
the aim of developing a facile and effective method for the labeling of peptides with carbon-11. The Pictet-Spengler reaction
of Trp and [11C]formaldehyde in acidic media (TsOH or HCl) afforded the desired [1-11C]Tpi in a moderate radiochemical yield.
Herein, the application of a Pictet-Spengler reaction to an aqueous solution of Trp•HCl gave the desired product with a
radiochemical yield of 45.2%. The RGD peptide cyclo[Arg-Gly-Asp-D-Tyr-Lys] was then selected as a substrate for the labeling
reaction with [11C]formaldehyde. The radiolabeling of a Trp•HCl-containing RGD peptide using the Pictet-Spengler reaction
was successful. Furthermore, the remote-controlled synthesis of a [1-11C]Tpi-containing RGD peptide was attempted by using
an automatic production system to generate [11C]CH3I. The radiochemical yield of the [1-11C]Tpi-containing RGD at the end of
synthesis (EOS) was 5.9 ± 1.9% (n = 4), for a total synthesis time of about 35 min. The specific activity was 85.7 ± 9.4 GBq/μmol
at the EOS. Copyright © 2013 European Peptide Society and John Wiley & Sons, Ltd.},
 pages = {663--668},
 title = {Carbon-11 radiolabeling of an oligopeptide containing tryptophan hydrochloride via a Pictet-Spengler reaction using carbon-11 formaldehyde},
 volume = {19},
 year = {2013}
}