Spectrophotometric determination of the ionization constant values (PKa ) of some amino acids (Methionine , cystine and cysteine )

摘要

A simple, rapid and sensitive method has been applied on three amino acids viz., methionine, cystine and cysteine, to estimate the ionization constant. Spectrophotometric measurements were carried out on the absorbance of each amino acid at different pH values. The results showed that the cystine and cysteine have one pK a , while the methionine gave two different pK a values by using this method.