Effect of Heavy Metal Lead on Protein Secondary Structure and Amino Acids of Barley Seedling Powder

This study was conducted in order to explore the effect of lead (Pb) stress on the nutritional value and flavor of barley seedling powder. Fourier transform infrared (FTIR) spectroscopy and targeted metabolomics based on liquid chromatography-mass spectrometry (LC-MS) were used for quantitative and qualitative analysis of protein secondary structure and amino acid contents in barley seedling powders with and without Pb stress during growth. The results showed that Pb stress led to the transformation of protein secondary structure in barley seedlings from disordered (β-turn and random coil) to ordered (α-helix) structure. Through high-throughput targeted metabolomic analysis, a total of 25 amino acids were identified and quantified in barley seedling powder. Pb stress decreased the contents of Arg, Pro and His, but increased the content of Val, which proves that Pb could reduce the nutritional value and sweetness, and increase the bitterness of barley seedling powder. These results provide some basic data for the development of barley-based health foods.