QUANTITATIVE-DETERMINATION OF AMINO-ACID LEVELS IN NEUTRAL AND GLUCOSAMINE-CONTAINING CARBOHYDRATE POLYMERS

Low-level (subnanomole) determination of amino acids in samples of nat urally derived polymeric carbohydrates has been demonstrated using vap or-phase acid hydrolysis and subsequent precolumn derivatization with 6 aminoquinolyl-N-hydroxysuccinimidyl carbamate. Application has been demonstrated for neutral polysaccharide polymers such as laminarin (be ta-1,3; branched), curdlan (beta-1,3; unbranched), pullulan (alpha-1,6 -maltotriose), glycogen (alpha-1,4-glucan), and inulin (polyfructose). Successful determination (acceptable recovery and lack of interferenc es) was possible in samples which also contained up to roughly 50 mu g amino sugars (e.g., chitosan or glucans with copurified glucosamine o ligomers), although optimum utility is for samples containing up to ca . 10 mu g total amines. The limit of quantification was roughly 20 ng protein/mg mg sample, based on analysis of reagent blanks, although th e limit of detection was much lower (ca. 0.1 ng protein/mg sample). In corporation of a relatively rapid hydrolysis (150 degrees C for 1.5 h) gave similar results to use of 110 degrees C for 24 h and allowed for relatively rapid processing. The method has shown good sensitivity, l inearity, ruggedness, and ease. Recovery has been optimized, although yield varied somewhat depending on polymer composition. (C) 1997 Acade mic Press