紫外照射下高铁肌红蛋白变化的同步荧光光谱指认

Synchronous Fluorescence Spectra Study on Changes in Metmyoglobin under Ultraviolet Irradiation

研究了猪心肌和马心肌高铁肌红蛋白(pMetMb、hMetMb)被紫外光照射后的荧光光谱变化,紫外光照射时间共设6个梯度,分别是0、5、10、20、30、60min。随着紫外光的照射,MetMb高级结构发生蜕变。利用同步荧光光谱指认了紫外照射对酪氨酸(Tyr)和色氨酸(Trp)的影响,紫外照射0～5min氨基酸残基吸收强度减小;5～30min吸收强度总体保持上升趋势;30～60min吸收强度减小。且指认出MetMb中Trp在该蛋白质肽链中的比例高于Tyr,pMetMb和hMetMb两种荧光光谱谱征变化类似。进一步指认了MetMb的heme-Fe3+荧光谱征变化,照射5min时heme-Fe3+荧光吸收强度降低,10min时荧光吸收强度有所跳跃,20min后持续下降,heme-Fe3+高级结构明显降解或被破坏,可能是MetMb丧失生物活性的又一荧光光谱变化特征。

The changes in porcine myocardial metmyoglobin （pMetMb） and horse myocardial metmyoglobin （hMetMb） under ultraviolet irradiation are studied comparatively by synchronous fluorescence spectra. The ultraviolet irradiation is designed for the six gradients of 0, 5, 10, 20, 30, 60 min. With the irradiation of ultraviolet light, disintegration happens in the senior structure of MetMb. Synchronous fluorescence spectra can identify the influences of ultraviolet induction on tyrosine （Tyr） and tryptophan （Trp）. The amino acid absorption value decreases for 0~Smin, increases for 5~30 min, and decreases again for 30--60 min. It is identified that the ratio of Trp in the protein peptide chain is higher than the proportion of Tyr and two kinds of fluorescence spectra in pMetMb and hMetMb have similar changes. Synchronous fluorescence spectra further identify the heme-Fe3＋ fluorescence spectra sign change in MetMb. The heme-Fe3＋ fluorescence intensity is reduced when MetMb has been exposured for 5 min, and fluorescence intensity becomes higher for 10 min. After 20 min, the senior structure of heme-Fe3＋ may be degraded or destroyed obviously, that may be fluorescence spectra variation characteristics in MetMb caused by the loss of biological activity.