Tecnología de los Alimentos, Facultad de Veterinaria, Universidad de Zaragoza, Miguel Servet, 177, 50013, Zaragoza, Spain.
Biochem Cell Biol. 2012 Jun;90(3):389-96. doi: 10.1139/o11-073. Epub 2012 Feb 14.
Heat denaturation of recombinant human lactoferrin (rhLf) from rice with 3 different iron-saturation degrees, holo rhLf (iron-saturated), AsIs rhLf (60% iron saturation), and apo rhLf (iron-depleted), was studied. The 3 forms of rhLf were subjected to heat treatment, and the kinetic and thermodynamic parameters of the denaturation process were determined. Thermal denaturation of rhLf was assessed by measuring the loss of reactivity against specific antibodies. D(t) values (time to reduce 90% of immunoreactivity) decreased with increasing temperature of treatment for apo and holo rhLf, those values being higher for the iron-saturated form, which indicates that iron confers thermal stability to rhLf. However, AsIs rhLf showed a different behaviour with an increase in resistance to heat between 79 °C and 84 °C, so that the kinetic parameters could not be calculated. The heat denaturation process for apo and holo rhLf was best described assuming a reaction order of 1.5. The activation energy of the denaturation process was 648.20 kJ/mol for holo rhLf and 406.94 kJ/mol for apo rhLf, confirming that iron-depleted rhLf is more sensitive to heat treatment than iron-saturated rhLf.
研究了 3 种不同铁饱和度的重组人乳铁蛋白（rhLf）的热变性，分别为全铁饱和的 holo rhLf、60%铁饱和度的 AsIs rhLf 和缺铁的 apo rhLf。对 3 种形式的 rhLf 进行热处理，并确定了变性过程的动力学和热力学参数。通过测量针对特定抗体的反应性丧失来评估 rhLf 的热变性。对于 apo 和 holo rhLf，D(t) 值（降低 90%免疫反应性所需的时间）随处理温度的升高而降低，铁饱和形式的值更高，这表明铁赋予 rhLf 热稳定性。然而，AsIs rhLf 在 79°C 和 84°C 之间表现出不同的耐热性增加行为，因此无法计算动力学参数。apo 和 holo rhLf 的热变性过程最好假设反应级数为 1.5。全铁饱和的 holo rhLf 的变性过程的活化能为 648.20 kJ/mol，而缺铁的 apo rhLf 的活化能为 406.94 kJ/mol，这证实了缺铁的 rhLf 比全铁饱和的 rhLf 对热处理更敏感。
