Department of Plant Sciences, North Dakota State University, Fargo, ND, 58108-6050, USA.
J Sci Food Agric. 2014 Jan 30;94(2):205-12. doi: 10.1002/jsfa.6229. Epub 2013 Jun 27.
High moisture before harvest can cause sprouting of the wheat kernel, which is termed pre-harvest sprouting (PHS). The aim of this study was to examine the variation in physicochemical properties of proteins in PHS-damaged (sprouted) hard red and white spring wheat genotypes. Specifically, protein content, enzyme activity and degradation of proteins were evaluated in sound and PHS-damaged wheat.
Protein contents of sprouted wheat samples were lower than that of non-sprouted samples; however, their differences were not significantly (P > 0.05) correlated with sprouting score. Sodium dodecyl sulfate (SDS) buffer extractable proteins (EXP) and unextractable proteins (UNP) were analyzed by high-performance size exclusion chromatography. PHS damage elevated endoprotease activity and consequently increased the degradation of polymeric UNP and free asparagine concentration in wheat samples. Free asparagine is known to be a precursor for formation of carcinogenic acrylamide during high heat treatment, such as baking bread. Free asparagine content had significant correlations (P < 0.01) with sprouting score, endoprotease activity and protein degradation.
Genotypes with higher endoprotease activity tend to exhibit a larger degree of degradation of UNP and higher free asparagine concentration in sprouted wheat samples.
收获前的高湿度会导致麦粒发芽，这被称为收获前发芽（PHS）。本研究旨在研究 PHS 损伤（发芽）硬红春小麦和白春小麦基因型中蛋白质理化性质的变化。具体而言，评估了健康和 PHS 损伤小麦中蛋白质含量、酶活性和蛋白质降解。
发芽小麦样品的蛋白质含量低于未发芽样品；然而，它们之间的差异与发芽评分没有显著相关性（P>0.05）。十二烷基硫酸钠（SDS）缓冲液可提取蛋白质（EXP）和不可提取蛋白质（UNP）通过高效尺寸排阻色谱进行分析。PHS 损伤会提高内切蛋白酶的活性，从而增加小麦样品中高分子量 UNP 和游离天冬酰胺的降解。众所周知，游离天冬酰胺是在高温处理（如烘焙面包）过程中形成致癌丙烯酰胺的前体。游离天冬酰胺含量与发芽评分、内切蛋白酶活性和蛋白质降解有显著相关性（P<0.01）。
内切蛋白酶活性较高的基因型在发芽小麦样品中往往表现出更高程度的 UNP 降解和更高的游离天冬酰胺浓度。
