Structural studies and cell proliferation activity of human Follistatin-like 1 in reducing and non-reducing conditions

Abstract

Human Follistatin-like 1, is a protein with multiple disulfide bonds involved in important physiological processes. The current research aimed to evaluate the relationship between the reduction of disulfide bonds and the function of human FSTL1. Human FSTL1 was expressed in a bacterial expression system, purified, and reduced using 4–16 mM dithiothreitol (DTT). The results showed that the proliferation in the presence of the reduced human FSTL1 with 16 mM was better than that of the non-reduced protein. While circular dichroism spectroscopy showed that the content of the secondary structure of human FSTL1 did not change significantly, fluorescence spectroscopy studies show that the surface hydrophobicity of human FSTL1 decreased after reduction of disulfide bonds. Molecular dynamics studies showed that the radius of gyration decreased in the presence of 16 mM DTT. Our results showed that the reduction of disulfide bonds in human FSTL1 increased the hydrophilicity of the surface and might have a compensatory effect on the decrease in the hydrophilicity caused by the lack of post-translational modifications in the bacterial expression system. The present study may be useful for future pathological studies.