Effects of different modification techniques on molecular structure and bioactivity of Bombyx mori pupa protein

Zhi-Feng Zhou, Zi-Xu Ren, Hai-Yan Yu, Jun-Qiang Jia, Zhong-Zheng Gui

School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang 212018, China.

Abstract

To improve the properties of silkworm (Bombyx mori) pupa protein (SPP), the effects of different modification techniques included enzymolysis, ultrasound, and micronization on the molecular structure and bioactivity of SPP has been evaluated in this study. The results showed that enzymolysis modification led to the most substantial change in the area and shape of the infrared (IR) absorption peaks, decreased in size with an increased number of cracks of modified protein by scanning electron microscopy images, followed by ultrasound and micronization modification. After modification by enzymolysis, ultrasound, and micronization, the sulfhydryl concentrations of SPP were increased by 48.56%, 34.82%, and 12.46%, respectively; disulfide bond concentrations were reduced by 40.47%, 10.79%, and 11.72%, respectively. Furthermore, the ratios of essential amino acids among total amino acids increased by 13.85%, 2.22%, and 6.93%, respectively. Antioxidant activity and ACE-inhibitory activity of SPP also increased notably after modifications.

Graphical abstract

Keywords: Biological activity; Bombyx mori pupa protein; Modification techniques; Physicochemical properties.