try
            {
                string realUserLogin = "ДОМЕН2\\realuser";

                string domain = "ДОМЕН2";
                string sysUserLogin = "ДОМЕН2\\sysusr";
                string sysUserPwd = "sysusrpwd";

                PrincipalContext ctx = new PrincipalContext(ContextType.Domain, domain, null, ContextOptions.SimpleBind, sysUserLogin, sysUserPwd);
                UserPrincipal principal = UserPrincipal.FindByIdentity(ctx, IdentityType.SamAccountName, realUserLogin);
      
                DirectoryEntry directoryEntry = (DirectoryEntry)principal.GetUnderlyingObject();

                PropertyValueCollection collectionTitle = directoryEntry.Properties["title"];                
                collectionTitle.Clear();
                collectionTitle.Add("Заместитель руководителя отдела");
                directoryEntry.CommitChanges();

            }
            catch (Exception ex)
            {
                SystemHelper.log.Error(ex.Message, ex);
                throw new Exception(String.Format("Ошибка при сохранении в AD: {0}", ex.Message));
            }