Observations on the use of 2,4,6-trinitrobenzenesulphonic acid for the determination of available lysine in animal protein concentrates
Abstract
The determination of available lysine in proteins by their reactions with 2,4,6-trinitrobenzenesulphonic acid has been examined in relation to the preparation of the sample, the conditions of the reaction, the hydrolysis of the trinitrophenylated protein and the effects of other amino-acids and related compounds. From these observations a revised method is proposed for the rapid routine screening of animal protein concentrates used in animal feeds. With the use of DL-lysine as a standard instead of ε-trinitrophenyllysine and with a simplified hydrolysis procedure, the technique is suitable for examining comparatively large numbers of samples. Interference by other amino compounds is slight, except that by cadaverine, hydroxylysine and ornithine.
Results are given for the levels of available lysine in a range of animal proteins, which compare closely with values obtained by the Carpenter procedure in which 1-fluoro-2,4-dinitrobenzene is used.