Analysis of amino acid variations of major proteins from severe acute respiratory syndrome coronavirus 2 / 第二军医大学学报

Objective To identify key amino acid variations of major proteins from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by biophysical methods. Methods Through amino acid sequence alignment, classification of variant amino acid residues, three-dimensional structure reconstruction of proteins, and electrostatic interaction analysis of amino acid residues, the key amino acid variations of major proteins from SARS-CoV-2 was analyzed with RaTG13, the bat coronavirus with the highest homology, as the reference. Results At least ten amino acid variations that affect the possible electrostatic interactions were identified in RNA-dependent RNA polymerase (RdRp), exoribonuclease (ExoN), uridylate-specific endoribonuclease (NendoU), and spike (S) protein from SARS-CoV-2. These variations may affect the spatial conformation and biological functions of the proteins. Conclusion The key amino acid variations of the major proteins from SARS-CoV-2 have been preliminarily identified, providing clues for understanding the genetic, pathogenic and epidemiological characteristics of the virus..

Relationship Between Intracardiovascular Smoke-like Echo and Erythrocytic Rouleaux / 中华超声影像学杂志

Intracardiovascular smoke-like echo always appears in the regions of stasis.Recently,we experimentally found that its appearance closely related to the erythrocytic rouleaux.(1)In vitro study:Erythrocytic suspension was observed by ultrasound and echofree can be seen on its sonogram.Under mi-croscope.the red blood cells presented dispersed phase.If equal amount of lymphocytic separated solution was put in the suspension,smoke-like echo appeared at the original fluid dark area and the red cells pres-ented pattern of rouleaux.(2)Animal experiment:Under physiological condition,velocity of blood flow israpid and echofree can be seen in the cardiovascular cavity.When blood flow velocity becomes slow or stasis,the shear force will reduce and even disappear,SO.red cells aggregated each other with their concave face and formed a rouleaux.As rouleaux structure was formed,its size became larger and it was nearer orlarger than the wavelength of ultrasound.therefre the reflections were produced and smoke-like echoappeared.It might be the mechanism for the formation of intracardiovascular smoke-like echo.