Practical Protein Chemistry - A. Darbre 1989

Determination of amino acid sequence using 4-dimethylaminoazobenzene-4'-isothiocyanate (manual procedure)
Introduction

J.-Y. CHANG (Pharmaceuticals Research Laboratories, CIBA-GEIGY Limited, 4002 Basle, Switzerland)

Determining the Amino Acid Sequence of Peptides via Edman Degradation relies on identifying the cleaved phenylthiohydantoin (PTH) Amino Acid Derivatives [11] by UV absorbance (λmах = 269 nm, ε = 16000). In a modified version of the method that employs 4-dimethylaminoazobenzene-4'-isothiocyanate (DABITC) instead of phenyl isothiocyanate (PITC), the resulting amino acid derivatives—4-dimethylaminoazobenzene-4'-thiohydantoins (DABTH)—are colored compounds with λmах = 520 nm (in an acidic medium) and ε = 47,000. The identification of DABTH-amino acid derivatives in the visible region is convenient and enables a significantly higher level of sensitivity compared to PTH derivatives. DABTH derivatives have proven valuable both for N-terminal peptide analysis [6] and for determining complete Amino acid sequences.

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A protocol has been developed that combines Two Types of DABITC–PITC double coupling for liquid-phase [5, 7, 10] and solid-phase [4, 7] Analytical Methods.



Last update: 06/08/2026

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