Influence of the biogenic polyamines spermine, spermidine, and putrescine as 
well as their derivatives on the replication enzymes of hepatitis C virus (HCV) 
was investigated. It was found that spermine and spermidine activate HCV 
RNA-dependent RNA polymerase (NS5B protein). This effect was not caused by the 
stabilization of the enzyme or by competition with template-primer complex, but 
rather it was due to achievement of true maximum velocity V(max). Natural 
polyamines and their derivatives effectively inhibited the helicase reaction 
catalyzed by another enzyme of HCV replication - helicase/NTPase (NS3 protein). 
However, these compounds affected neither the NTPase reaction nor its activation 
by polynucleotides. Activation of the HCV RNA polymerase and inhibition of the 
viral helicase were shown at physiological concentrations of the polyamines. 
These data suggest that biogenic polyamines may cause differently directed 
effects on the replication of the HCV genome in an infected cell.