Fibril Formation of Bovine α-Lactalbumin Is Inhibited by Glutathione

The current research is aimed at exploring the inhibitory effect of glutathione on fibril formation of an important four disulfide bond-containing whey protein, α-lactalbumin. Through numerous spectroscopic techniques and transmission electron microscopy, we found that the inhibition of amyloid formation of α-lactalbumin was dependent on the glutathione concentration and fibrillation was significantly attenuated in the presence of 5 mM glutathione. Moreover, the data from the measurements using 4,4′-dithiodipyridine reagent revealed that the treatment of α-lactalbumin with glutathione led to the exposure of sulfhydryl groups. Also, the observed inhibition of α-lactalbumin by glutathione was correlated with the reduction of disulfide bridges of protein. The results presented here suggest that the addition of food compatible reducing agent/dietary supplement such as glutathione would be useful for preventing the formation of milk protein fibrillar aggregates. The presence of these resulting aggregates can then, in turn, be used to modulate the key properties of food products such as protein beverage and yogurt.