Effect of marinating ingredients on temperature-induced denaturation of hemoglobin and its relation to red blood spot formation in cooked chicken breast

Red blood spot (RBS) commonly found in cooked chicken breast has caused severe economic loss as it is perceived as a sign of undercooked product. The objectives of this study were to investigate the cause of RBS as related to common ingredients used in marination, based on both chicken breast and isolated chicken hemoglobin (Hb) models. The effect of sodium chloride (NaCl), sodium tripolyphosphate (STPP), and glucose on thermal denaturation of Hb was investigated along with the extent of RBS formation in cooked marinated chicken breast. After vacuum tumbling for 65 min and subsequent storage at 4 °C for 20 hr, STPP and glucose were not absorbed into the center of chicken breast. However, Na⁺ was absorbed after 12 hr storage. The denaturation temperature (T_d) of isolated chicken Hb decreased to 65.8 °C in the presence of 1.5 M NaCl, while that of the control was 69.4 °C. STPP at pH 9 decreased T_d of Hb to 61.4 °C. The alkaline pH induced by STPP destabilized the Hb structure. RBSs were observed at 100% incidence when cooked to core temperatures of 50 and 70 °C for 1 min. RBSs were completely eliminated at core temperature of 85 °C. The ingredients used during marination appeared to have a minimal effect on RBS formation due to their limited absorption into the chicken breast. The cooking temperature is a major factor governing RBSs, as it directly affects the denaturation of Hb.     

荧光光谱法研究茶碱与血红蛋白的相互作用

运用荧光光谱法研究了茶碱与牛血红蛋白(BHb)的相互作用,茶碱对牛血红蛋白的荧光猝灭过程主要为静态猝灭。测定了不同温度下该反应的结合常数、结合位点数及结合热力学参数,热力学参数的变化,表明上述作用过程是一个熵增加、自由能降低的自发分子间作用过程,而且是以疏水作用为主。用同步荧光技术考察了茶碱对BHb构象的影响。     

血红蛋白固定在Ti0.865O2纳米片层间的直接电化学和电催化

通过对层状纤铁矿型钛酸锂钾进行剥离,可以制备得到Ti0．865O2纳米片溶胶。将Ti0．865O2纳米片作为载体固定血红蛋白（Hb）,制备得到Hb/Ti0．865O2/纳米片修饰的热解石墨（PG）电极。在Ti0．865O2纳米片层间,Hb能实现与电极的直接电子转移。在pH值为5．6的磷酸盐缓冲溶液中,该修饰电极的循环伏安曲线上显示出一对可逆的氧化还原峰,式电位为-230mV（vs．Ag/AgCl）。该修饰电极对H2O2有良好的电催化响应,线性响应范围为50μM到2．2mM,灵敏度为10μA．mM^-1．cm^-2。     

用化学计量学方法评定贮存血液细胞品质因素

用自动血液分析仪测定贮存全血的10个化验参数测定,按照主成分分析方法量化处理、计算化验数据,在主成分分析基础上,提出"细胞品质因素"作为综合评定指标的概念.用坐标平面图对贮存全血质量作出准确量化评定.结果说明"细胞品质因素"能较理想的评价贮存血液的质量,表明化学计量学方法在医学化验数据中可发现更多、更有价值的化学规律和生物信息.     

利用物理模型合成皮肤图像

为了获得各种丰富和逼真的皮肤图像,在对皮肤结构和皮肤组成进行分析的基础上,提出了一种基于物理模型的鲁棒算法对输入的单张皮肤图像自动进行色素分离,并在此基础上实现了全局性和局部性的合成。输入的图像首先被分成N个子区域,并依次在每个子区域利用ICA算法提取分离向量,之后对得到的分离向量进行合理性验证。如果分离向量不合理,则丢弃,在下一个子区域重复上述过程。最后,从所有的合理分离向量中得到最终的分离向量,分离得到黑色素和血色素的密度分布图。通过改变色素的密度可以进行全局性合成,也可以利用密度信息选取感兴趣区域进行局部性合成。实验结果表明,该算法非常有效,可以对人体皮肤图像进行"电子化妆",重新生成更多逼真的合成图像。     

纳米金-壳聚糖-血红蛋白/普鲁士蓝/金电极检测过氧化氢

在普鲁士蓝修饰的金电极上,通过纳米金/壳聚糖复合膜固定血红蛋白,研制了安培型过氧化氢生物传感器,线性范围和检测限分别为1～5 000 umol/L和0.27umol/L.     

Oxygen-dependent enhancement of hydrogen production by engineering bacterial hemoglobin in Escherichia coli

H₂ production under aerobic conditions has been proposed as an alternative method to overcome the fundamentally low yield of H₂ production by fermentative bacteria by maximizing the number of electrons that are available for H₂. Here, we engineered Vitreoscilla hemoglobin (VHb) in Escherichia coli to study the effects of this versatile oxygen (O₂)-binding protein on oxic H₂ production in a closed batch system that was supplemented with glucose. The H₂ yields that were obtained with the VHb-expressing E. coli were greatly enhanced in comparison to the negative control cells in culture that started with high O₂ tensions. The formate hydrogen lyase (FHL) activity of oxically cultured, VHb-expressing cells was also much higher than that of the negative control cells. Through inhibitor studies and time-course experiments, VHb was shown to contribute to the improved H₂ yield primarily by increasing the efficiency of cellular metabolism during the aerobic phase before the onset of H₂ production and not by working as an O₂-scavenger during H₂ production. This new approach allowed more substrate to remain to be further utilized for the production of more H₂ from limited resources. We expect that VHb can be successfully engineered in potential aerobic H₂-producing microbial systems to enhance the overall H₂ production yield. In addition, the remarkably high FHL activity of oxically grown, VHb-expressing cells may make this engineered strain an attractive whole-cell biocatalyst for converting formate to H₂.