Location: Soybean and Nitrogen Fixation Research
Title: A Modified Amino Acid Analysis Using PITC Derivatization for Soybeans with Accurate Determination of Cysteine and Half-Cystine Authors
Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 4, 2009
Publication Date: N/A
Interpretive Summary: A simple and rapid amino analysis for soybean seeds with accurate determination of cysteine and half-cystine was successfully developed. The method uses a gas-phase hydrolysis combined with derivatization of hydrolysates and HPLC analysis. The technique not only was proven to be accurate using reference protein as a check but also was reliable when tested with large numbers of soybean samples generated from field experiment.
Technical Abstract: Breeding efforts to change amino acid profile of seed protein and the assessment of genetic variation for amino acid composition among soybean germplasm resources have been hampered by lack of a rapid and inexpensive method for amino acid determination. A modified procedure presented here is based partly on a gas-phase hydrolysis and precolumn derivatization for HPLC analysis described by Heinrikson and Meredith (Anal. Biochem. 136:65-74, 1984). The procedure accurately measured cysteine and half-cystine in samples. The method was also proven to be accurate using reference protein with known amino acid composition. It is reliable and can be automated for daily analysis with large number of samples. The method was also tested with soybean seeds harvested from a two-replicated multi-location soybean field experiment. It was found that no soybean cultivar by location interaction was significant for any of the amino acids which demonstrate that amino acid compositions were generally stable across a range of environments, and that the repeatability of the measurement itself was high. The error associated with the determination was also low as demonstrated in the analysis of variance.