Ultrasound is the sound whose frequency is too high for humans to hear which is the within frequency range of 20 Hz–20 kHz, and the frequency of ultrasound is above 20 kHz.The aim of this study was to observe the effect of ultrasound and sonication (20 kHz prob for 15 and 30 min) on stability of α-lactalbumin. The interaction of anionic surfactant, SDS, and cationic surfactant, DTAB, with α-lactalbumin has been investigated in phosphate buffer (pH=7) in the absence and presence of ultrasound using by UV and fluorescence spectroscopy. 〖∆G〗_H2O^0of protein in the absence of ultrasound has the lowest value and this value increases whit increase the time of ultrasound. Fluorescence spectra of α-lactalbumin in the presence of ultrasound show a decrease in fluorescence intensity of the protein excited whit 295 nm wavelength. Therefore, ultrasound act on α-lactalbumin as a quencher.

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