Structural biochemistry. Part XII. Synthesis of tobacco mosaic virus protein unit 150-158

The C-terminal nonapeptide sequence of tobacco mosaic virus protein was synthesized by a fragment-condensation approach. Important steps in the synthesis involved coupling of N-benzyloxycarbonyl-L-threonyl-L-serine azide with glycyl-L-prolyl-L-alanyl-L-threonine methyl ester and condensing the mixed carbonic anhydride derived from N-t-butoxycarbonyl-L-leucyl-L-valyl-L-tryptophan and isobutyl chloroformate with the hexapeptide (Vb) to provide the nonapeptide N-t-butoxycarbonyl-L-leucyl-L-valyl-L-tryptophyl-L-threonyl-L-seryl-glycyl-L- prolyl-L-alanyl-L-threonine (VIIIb).