ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 38, Number 10
JKCSEZ 38(10)
August 20, 1994 

Higher order structure of 5S rRNA isolated from Xanthomonas celebensis was examined using angiogenic extracted from milk. Angiogenin cleaved exclusively 3' P-O bonds on the far sides of pyrimidines in the single-stranded sequences of 5S rRNA. Whereas angiogenin acted only on the loop d of 5S rRNA at pH 7.0 in the presence of 10 mM Mg2+, it acted on all the loops (a, b, c and d) except loop e in the absence of Mg2+. In the absence of Mg2+, bonds U74-G75, U77-A78 and U103-A104 were highly susceptible to the action of angiogenin both at pH 7.0 and at pH 3.5. On the other hand, at pH 3.5 in the absence of Mg2+ angiogenin strongly cleaved the bond C17-G18 of loop a and the bond U55-G56 of loop b. The results lead us to the following conclusion. First, angiogenin can be used as one of the probes for the tertiary structure analysis of 5S rRNA. Second, the structure of loop d of 5S rRNA is variable depending on the concentrations of Mg2+ and H1+.