The crystal structure of Ig81 domain confirms that the domain folds into a compactβ-sandwich,but with an evanescent BC-loop at the N-terminus.It is not clear whether the divergent BC-loop has an effect on the stabili...The crystal structure of Ig81 domain confirms that the domain folds into a compactβ-sandwich,but with an evanescent BC-loop at the N-terminus.It is not clear whether the divergent BC-loop has an effect on the stability of the shear topology formed by two of parallel A and Gβ-strands.In this paper,two Cαatoms in A and Gβ-strands were selected as two stress points,and the domains were stretched in opposite directions as a speed of 2.5×10-4 nm·ps-1.Under the same stretching conditions,100 steered molecular dynamics(SMD)runs were performed.The free energy of Ig81 was constructed as a function of the increasing distance between the two stress points using the Jarzynski's equality.For comparison,the free energy profile of the Ig27 domain was reconstructed with same method.The results show that the work done to unfold Ig81 is greater than the work done to unfold Ig27,and that the folding barrier of Ig81 is lower than that of Ig27.This suggests that the presence of the distinctive long BC-loop increases the sta-bility of the shear topology,thereby improving the mechanical strength of the protein.展开更多
基金supported by Natural Science Foundation of Shandong Province(ZR2021QD126)。
文摘The crystal structure of Ig81 domain confirms that the domain folds into a compactβ-sandwich,but with an evanescent BC-loop at the N-terminus.It is not clear whether the divergent BC-loop has an effect on the stability of the shear topology formed by two of parallel A and Gβ-strands.In this paper,two Cαatoms in A and Gβ-strands were selected as two stress points,and the domains were stretched in opposite directions as a speed of 2.5×10-4 nm·ps-1.Under the same stretching conditions,100 steered molecular dynamics(SMD)runs were performed.The free energy of Ig81 was constructed as a function of the increasing distance between the two stress points using the Jarzynski's equality.For comparison,the free energy profile of the Ig27 domain was reconstructed with same method.The results show that the work done to unfold Ig81 is greater than the work done to unfold Ig27,and that the folding barrier of Ig81 is lower than that of Ig27.This suggests that the presence of the distinctive long BC-loop increases the sta-bility of the shear topology,thereby improving the mechanical strength of the protein.
