Add a property to gridview and enable required field validator on checkbox checked event.

Add Property to a gridview to use with Javascript.

 protected void gridview1_RowDataBound(object sender, GridViewRowEventArgs e)

    {

      #region Add-Parameter-onJavaScript-Functions

           if (e.Row.RowType == DataControlRowType.DataRow)

          {

            CheckBox chk = new CheckBox();

            chk = e.Row.FindControl("chkIsEdit") as CheckBox;

            chk.Attributes.Add("onChange", "EnableFields(" + e.Row.RowIndex.ToString() + ")");

          }

      #endregion

    }

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Javascript Code 

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