McKerchar Hannah, Dyer Jolon M, Gerrard Juliet A, Maes Evelyne, Clerens Stefan, Dobson Renwick C J
Biomolecular Interaction Centre, School of Biological Sciences, University of Canterbury, Christchurch 8140, New Zealand.
Riddet Institute, Based Massey University, Palmerston North 4442, New Zealand.
Food Chem X. 2023 Jul 23;19:100800. doi: 10.1016/j.fochx.2023.100800. eCollection 2023 Oct 30.
Formation of lysinoalanine protein-protein crosslinks during food processing adversely impacts nutritional value. However, mapping lysinoalanine directly in food is challenging. We characterized the fragmentation pattern of lysinoalanine crosslinks in synthetic peptide models over a range of pH and time treatments using mass spectrometry. A putative diagnostic ion resulting from the cleavage of the α-carbon and β-carbon of lysinoalanine is identified in MALDI MS/MS spectra. This represents the first step in mapping lysinoalanine in real food samples with higher precision than currently identifiable through standard or customized software. We then determined a correlated trend in the reduction of disulfide bonds and formation of lysinoalanine with increasing pH and time. Mapping lysinoalanine formation is critical to enhance our understanding of molecular processes impacting the nutritional value of foods, including notably in the development of protein alternatives that use alkaline treatment to extract protein isolates.
食品加工过程中赖氨酰丙氨酸蛋白质-蛋白质交联的形成对营养价值产生不利影响。然而，直接在食品中测定赖氨酰丙氨酸具有挑战性。我们使用质谱对合成肽模型在一系列pH值和时间处理条件下赖氨酰丙氨酸交联的碎片化模式进行了表征。在基质辅助激光解吸电离串联质谱（MALDI MS/MS）谱图中鉴定出一种由赖氨酰丙氨酸的α-碳和β-碳裂解产生的推定诊断离子。这代表了以比目前通过标准或定制软件可识别的更高精度在实际食品样品中测定赖氨酰丙氨酸的第一步。然后，我们确定了随着pH值和时间增加二硫键减少和赖氨酰丙氨酸形成的相关趋势。测定赖氨酰丙氨酸的形成对于增强我们对影响食品营养价值的分子过程的理解至关重要，特别是在开发使用碱性处理来提取蛋白质分离物的蛋白质替代品方面。
