Quantitative Analysis of Cystine, Methionine, Lysine, and Nine Other Amino Acids by a Single Oxidation-4 Hour Hydrolysis Method

Abstract

The sulfur-containing amino acids cystine and methionine play important roles in animal, especially avian, nutrition. Because these ndror-containing amino acids are destroyed to varying extents by 6N HC1 hydrolysis, oxidation and hydrolysis of cystine to cysteic add and methionine to methionine sulfone have been widely used for determination of cystine and methionine. Lysine is considered the next limiting amino acid after the sulfur amino acids in poultry •ntrition; therefore, determination of the amino acid content of rations focuses first on these 3 amino acids. The objective of this investigation was to establish whether lysine and other amino acids could be accurately determined in proteinaceous materials which had mdergone performic acid oxidation. To perform this evaluation, lysine was determined in a variety of protein-containing materials both with and without performic acid oxidation. Performic acid oxidation followed by 6N HC1 hydrolysis at 145°C for 4 h allows accurate measurement of 3 amino acids especially important to poultry nutrition, cystine, methionine, and lysine, in a single preoxidized hydralysate; this method can be extended to another 9 protein amino adds.

Lesquerella fendleri protein fractionation and characterization

“…Nitrogen was determined in duplicate by AOAC Official Methods 990.03, by combustion analysis, and 976.05, by the automated Kjeldahl method (7). The amino acids were determined by cation exchange chromatography in a Beckman 6300 amino acid analyzer (Beckman Instruments, San Ramon, CA) after samples were hydrolyzed by 6 N HCl for 4 h at 145°C (8). Methionine and cystine were oxidized by performic acid before hydrolysis (9), and tryptophan was determined by a colorimetric method after enzymatic hydrolysis by pronase (10,11).…”

Characterization of Select Wild Soybean Accessions in the USDA Germplasm Collection for Seed Composition and Agronomic Traits

“…The contents of 12 amino acids were measured by a single oxidation 4-h hydrolysis method (Gehrke et al, 1987). The 12 amino acids are alanine, aspartic acid, cysteine, glutamic acid, glycine, isoleucine, leucine, lysine, methionine, proline, threonine, and valine.…”

Effects of Lysine on Growth of Tilapia Fed Diets Rich in Corn Gluten Meal

“…Digestible energy was calcu-lated as 18.9, 16.8, and 37.7 kJ/g for protein, carbohydrate, and fat, respectively (Wang et al 1985). Samples for amino acid analyses were hydrolyzed at 145°C for 4 hr (Gehrke et al 1987), and methionine and cystine were oxidized with performic acid before hydrolysis (Moore 1963). Amino acids were determined in an amino acid analyzer (model 6300, Beckman Instruments, San Raman, CA) by cation-exchange chromatography.…”