Cytokinin Ribosides as Inhibitors of Ribonuclease Activity on Ribosomes From Fenugreek (Trigonella foenum-graecum L.)

Abstract

Ribonuclease activity on washed ribosomes, isolated from dark-incubated fenugreek cotyledons, depended on the presence of MgCl₂ or spermine. Under appropriate conditions, the digestion of poly(C) was inhibited by 48% at 8 x 10^-7 M 6-isopentenyladenosine, that of poly(U) was less sensitive to this riboside whilst no inhibition was observed with poly(A) as substrate. The digestion of poly(C) was inhibited by both 6-isopentenyladenine and by triacanthine (3-isopentenyladenine). Digestion of natural RNAs was also inhibited by 6-isopentenyladenosine but less so by other cytokinin ribosides and by 7-methylguanosine; it was not inhibited by unmodified nucleosides.