Andersen H J, Johansen H S, Shek C K, Skibsted L H
Chemistry Department, Royal Veterinary and Agricultural University, Frederiksberg C, Denmark.
Z Lebensm Unters Forsch. 1990 Oct-Nov;191(4-5):293-8. doi: 10.1007/BF01202429.
The exchange of nitric oxide in nitrosylmyoglobin, the heme pigment of nitrite-cured meat, has been studied using nitrogen-15 labelling in aqueous solution under conditions (pH, concentration of ascorbate and nitrite) similar to those prevailing in meat during the curing process, and has been found to have a half-life of approximately 2 h at 40 degrees C. One nitric oxide molecule is coordinated to the iron(II) centre of a myoglobin molecule and, in weakly acidic aqueous solution under anaerobic conditions, the exchange rate of the bound nitric oxide is proportional to the concentration of nitrosylmyoglobin, nitrite and hydrogen ion. The rate of exchange has a moderate temperature dependence, corresponding to an activation barrier of delta H+- = 47 +/- 3 kJ.mol-1 at 25 degrees C and pH 5.9, a value dramatically lower than that found for the enthalpy of activation for the oxidation of nitrosylmyoglobin by molecular oxygen, delta H+- = 110 kJ.mol-1. The difference in temperature dependence between the exchange and the autoxidation is discussed in relation to the function of nitrosylmyoglobin as antioxidant in cured meat products.
利用氮-15标记技术，在类似于肉类腌制过程中的条件（pH值、抗坏血酸盐和亚硝酸盐浓度）下，对亚硝酸盐腌制肉中的血红素色素亚硝酰肌红蛋白中的一氧化氮交换进行了研究。结果发现，在40℃时，其半衰期约为2小时。一个一氧化氮分子与肌红蛋白分子的铁（II）中心配位，在厌氧条件下的弱酸性水溶液中，结合的一氧化氮的交换速率与亚硝酰肌红蛋白、亚硝酸盐和氢离子的浓度成正比。交换速率对温度有适度的依赖性，在25℃和pH 5.9时，对应的活化能垒ΔH‡ = 47±3 kJ·mol-1，该值远低于亚硝酰肌红蛋白被分子氧氧化的活化焓ΔH‡ = 110 kJ·mol-1。结合亚硝酰肌红蛋白在腌制肉制品中作为抗氧化剂的功能，讨论了交换和自氧化在温度依赖性上的差异。
