with one strategically important derivative , a molecule containing the amino acid replacement , cys264 -- -- gly [ ( cys264 -- -- gly ) -rt-pa ] , a change resulting in the loss of covalent attachment of the heavy and light chains of tcrt-pa , the amidolytic activities of neither the single-chain nor the two-chain form of the molecule were stimulated by the presence of the above two positive effectors .
C0002520
amino acid
C0017890
gly