Chromatographic analysis of the amino acid composition of gallstones

Abstract

Gallstone disease (cholelithiasis) is a multifactorial disease characterised by the formation of gallstones. Studying the composition of gallstones is necessary to understand the mechanism of their formation and to solve many practical issues. At present, it is not clear which protein component is involved in the formation of gallstones and how it is related to their components. The study showed the possibility of qualitative and quantitative determination of amino acids in the composition of gallstones of men and women of different ages using a GC-17A gas chromatograph (Shimadzu). Analysis of the amino acid composition of gallstones includes acid hydrolysis of samples with 6M HCl at 105C° for 12 hours, subsequent purification, obtaining derivatives of isolated amino acids, and their determination by gas chromatography. This technique enables the determination of D- and L-forms of amino acids. Statistical processing of the obtained data was carried out using Statistica 6.0. The study revealed that cholesterol gallstones belonging to women up to 50 years of age have the lowest amino acid content. The amino acid composition of cholesterol gallstones is dominated by glycine and L-forms of serine, alanine, and glutamic acid. Cholesterol gallstones with mineral content are typical for elderly women (over 60 years) and middle-aged men (from 37 years), and have higher amino acid content than cholesterol gallstones. Glycine and the L-forms of leucine, glutamic acid, and asparagic acid are prevalent in these types of gallstones. The highest amino acid content was recorded in pigment gallstones of both men and women over 55 years of age. The amino acid composition of pigment gallstones is dominated by glycine and L-forms of glutamic acid, asparagic acid, leucine, and alanine. In cholesterol gallstones, no D-amino acids were found. In cholesterol gallstones with mineral content and pigmented gallstones, D-aspartic acid was detected. The obtained results allow us to recommend the method of gas chromatography for studying the amino acid composition of gallstones.