Structural Properties of Human Chorionic Gonadotropin (hCG) Affected by Ultrasonic Irradiation: An in Vitro Study

Abstract

Human chorionic gonadotropin (hCG) is a glycoprotein hormone that is an essential biomarker in oncology and pregnancy. The objective of this research was to examine the effect of ultrasonic irradiation (40 kHz) in various times of exposure (10 to 60 min) on the structure of hCG. The UV-Visible and near-UV CD data illustrated that ultrasonic irradiation could induce alterations in the tertiary structure of hCG and these conformational variations were irreversible. The ultrasonic-induced variations were observed in the intrinsic fluorescence emission. Furthermore, after long periods of exposure, ANS affinity to hCG incremented considerably. A transition to the random coil was observed in far-UV CD data. Ultrasonic irradiation could increment the negative surface charge on hCG. The effect of ultrasonic time revealed initial increment and eventual reduction in hCG size. After 60 min exposure, some new bands were observed at the SDS-PAGE profile of hCG. Collectively, our in vitro experiments demonstrated the sensitive balance between various noncovalent interactions in the structure of hCG could be easily disrupted after ultrasonic treatments. Results from this study are useful to achieve a better understanding of the ultrasonic irradiation physicochemical effects on proteins. Besides, can help to determine safe limits for people particularly, pregnant women.