  The possibility for an observation of a narrow penta-quark $Z^+$ baryon in
$NN$ reactions is discussed. It is shown that the $pp{\to}n\Sigma^+K^+$
reaction at excess energies around 100 MeV above threshold provides optimal
conditions for $Z^+$ baryon detection by an analysis of the $nK^+$ invariant
mass spectrum, if the $Z^+$ mass is located around 1.5 GeV involving a rather
narrow width.
