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Abstract:
To construct a possible model of hydrolytic enzymes, the sequential polypeptide H[Cys(Acm)-Ser-Phe-Glu-Glu]nOH, n = 3–110, was prepared by polycondensation of H-Cys(Acm)-Ser(But)-Phe-Glu(OBut)-Glu(OBut)-O Su/1-hydroxybenzotriazole. In a solid state the polypeptide material showed β-conformation both before and after cleavage of t-butyl protecting groups.
The pentapeptide unit was synthetized by the Merrifield method utilizing modifications as follows: Gel phase synthesis on < 0.5% cross-linked copolystyrene (quasi dissolved state). Centrifugal reactor. Ddz-amino acids, deprotected by 5% trifluoroacetic acid/dichloromethane/ 15 min. 3-Nitrophthalic anhydride to suppress formation of false sequences. Continuous photometric control of the completion of all operations during synthesis and transesterification, yielding Ddz-Cys(Acm)-Ser(But)-Phe-Glu-(OBut)-Glu(OBut)-OMe (0.827 g; 53%, m.p. 180–182°).
