Ioannou Aristos, Varotsis Constantinos
Department of Environmental Science and Technology, Cyprus University of Technology, Limassol, Cyprus.
PLoS One. 2017 Nov 14;12(11):e0188095. doi: 10.1371/journal.pone.0188095. eCollection 2017.
High performance liquid chromatography (HPLC) coupled with a Fraction Collector was employed to isolate Maillard reaction products (MRPs) formed in model systems comprising of asparagine and monosaccharides in the 60-180°C range. The primary MRP which is detected at 60°C is important for Acrylamide content and color/aroma development in foods and also in the field of food biotechnology for controlling the extent of the Maillard reaction with temperature. The discrete fractions of the reaction products were reacted with Hemoglobin (Hb) and Myoglobin (Mb) at physiological conditions and the reaction adducts were monitored by UV-vis and Attenuated Total Reflection-Fourier transform infrared (FTIR) spectrophotometry. The UV-vis kinetic profiles revealed the formation of a Soret transition characteristic of a low-spin six-coordinated species and the ATR-FTIR spectrum of the Hb-MRP and Mb-MRP fractions showed modifications in the protein Amide I and II vibrations. The UV-vis and the FTIR spectra of the Hb-MRPs indicate that the six-coordinated species is a hemichrome in which the distal E7 Histidine is coordinated to the heme Fe and blocks irreversibly the ligand binding site. Although the Mb-MRPs complex is a six-coordinated species, the 1608 cm-1 FTIR band characteristic of a hemichrome was not observed.
采用高效液相色谱（HPLC）结合馏分收集器，分离在60 - 180°C范围内由天冬酰胺和单糖组成的模型体系中形成的美拉德反应产物（MRPs）。在60°C检测到的主要MRP对食品中丙烯酰胺含量以及颜色/香气的形成很重要，在食品生物技术领域对于控制美拉德反应随温度的程度也很重要。将反应产物的离散馏分在生理条件下与血红蛋白（Hb）和肌红蛋白（Mb）反应，并通过紫外可见光谱和衰减全反射 - 傅里叶变换红外（FTIR）光谱法监测反应加合物。紫外可见动力学曲线揭示了低自旋六配位物种特有的Soret跃迁的形成，Hb - MRP和Mb - MRP馏分的ATR - FTIR光谱显示蛋白质酰胺I和II振动发生了变化。Hb - MRPs的紫外可见光谱和FTIR光谱表明，六配位物种是一种半色素，其中远端E7组氨酸与血红素铁配位并不可逆地阻断配体结合位点。虽然Mb - MRPs复合物是一种六配位物种，但未观察到半色素特有的1608 cm-1 FTIR谱带。
