STUDIES ON PEPTIDES. CXXV. 3-(3-P-METHOXYBENZYLTHIOPROPIONYL)THIAZOLIDINE-2-THIONE AND ITS ANALOGS AS REAGENTS FOR THE INTRODUCTION OF THE MERCAPTO GROUP INTO PEPTIDES AND PROTEINS

A new SH-introducing reagent, 3-(3-p-methoxybenzylthiopropionyl) thiazolidine-2-thione (MTPTT), was prepared by condensation of 3-p-methoxybenzylthiopropionic acid and thiazolidine-2-thione using DCC. Reaction of MTPTT with peptides can be monitored by following the disappearance of the pale yellow color of the reagent. As an example, synthetic human growth hormone-releasing factor (hGRF-40) was treated with MTPTT, followed by 1M trifluoromethanesulfonic acid-thioanisole/trifluoroacetic acid. The resulting HS-CH2CH2-CO-(hGRF-40) was conjugated with bovine serum albumin (BSA) by using a newly introduced heterobifunctional conjugating reagent, 2, 4-dinitrophenyl p-(β-nitrovinyl) benzoate for antigen preparation. Four other similar SH-introducing reagents were also prepared.