Using DRIFT Molecular Spectroscopy with Uni- and Multivariate Spectral Techniques To Detect Protein Molecular Structure Differences among Different Genotypes of Barley

The objectives of this study were to characterize protein molecular structure using DRIFT spectroscopy with univariate and multivariate molecular spectral analyses and identify the structure differences in both hull and seeds among six spring barley varieties [AC Metcalfe (malting-type), CDC Dolly (feed-type, spring forage type), McLeod (feed-type), CDC Helgason (feed-type), CDC Trey (feed-type), CDC Cowboy (feed-type)]. The molecular structure spectral analyses involved protein amide I and II region ca. 1716−1485 cm−1 (attributed to protein amide I CO and C−N stretching; amide II N−H bending and C−N stretching) together with agglomerative hierarchical cluster (CLA) and principal component analyses (PCA). The results showed that the molecular spectral techniques were able to identify spectral differences associated with the molecular structural differences among the barley varieties. The molecular spectral analyses at the region of ca. 1715−1485 cm−1 together with the cluster and principal component analyses were able to show that the molecular structures of the seeds (NOT hull) exhibited distinguished differences among the barley varieties. It was found that CDC Helgason had the distinguished differences from AC Metcalfe, McLeod, and CDC Cowboy in both protein amide I and II. The molecular spectral technique provides a new approach for plant protein molecular structure and biopolymer conformation study.