Synthesis and evaluation of L-cystathionine as a standard for amino acid analysis

Abstract

L-Cystathionine is a key nonprotein amino acid related to metabolic conditions. The quantitative determination of L-cystathionine in physiological fluids by amino acid analysis is important for clinical diagnosis; however, certified reference material for L-cystathionine with satisfactory purity, content, and quantity has been unavailable until recently. Consequently, a practical and simple method for the preparation of L-cystathionine was examined, which involves thioalkylation of N-tert-butoxycarbonyl-L-cysteine tert-butyl ester, derived from L-cystine, with (2S)-2-(tert-butoxycarbonyl)amino-4-iodobutanoic acid tert-butyl ester, derived from L-aspartic acid, to obtain L-cystathionine with protecting groups, followed by single-step deprotection under mild conditions. This method produces L-cystathionine in high purity (99.4%) and having sufficient percentage content according to amino acid analysis, which could be used as a standard for the amino acid analysis of physiological fluids.

L-Cystathionine Protects against Homocysteine-Induced Mitochondria-Dependent Apoptosis of Vascular Endothelial Cells

“…L-cystathionine is a nonprotein thioether containing amino acids and is mainly produced in the metabolic transformation process of methionine to cysteine in the body [10]. Previous studies on L-cystathionine have focused on it as a key amino acid associated with the metabolic state of sulfur-containing amino acids [11]. In recent years, studies have shown that it plays an important role in cardiovascular protection other than merely a metabolite in the methionine metabolic pathway.…”