In vitro iodination of plant ribonucleic acids.
The optimum conditions for in vitro iodination of RNAs have been established which yield specific radioactivities ranging from 10 x 10(4) to 10 x 10(6) cpm/mug. A nomogram has been constructed by correlating specific radioactivities of RNA with concentration of KI, RNA, and (125)I. This nomogram can be used to determine the conditions for the desired specific radioactivities for any unknown RNA. The in vitro iodinated RNA has been compared with in vivo labeled RNA for hybridization characteristics. Competition hybridization between (125)I-labeled chloroplast-rRNA and unlabeled pea (Pisum sativum) chloroplast-rRNA was identical to that found using [(32)P]chloroplast-rRNA. Thermal stability of DNA-(125)I-rRNA hybrids was similar to the thermal stability of DNA-[(32)P]rRNA hybrids. The iodinated RNA was not found to have undergone any changes in its hydrogen-bonding properties.
Meeker
R R
RR
Department of Molecular Biology and Biochemistry, University of California, Irvine, California 92664.
Thomas
J R
JR
Tewari
K K
KK