TY - JOUR
T1 - Effects of substrate structure on the kinetics of circle opening reactions of the self-splicing intervening sequence from Tetrahymena thermophila
T2 - Evidence for substrate and Mg2+ binding lnteractions
AU - Sugimoto, Naoki
AU - Tomka, Mary
AU - Kicrzek, Ryszard
AU - Bevilacqua, Philip C.
AU - Turner, Douglas H.
N1 - Funding Information:
This work wassupported byNational Institutes of Health Grant GM22939 and theOffice of Naval Research. We thank Dr. L. Friedrlch for his nonlinear, least-squares-fitting computer program, JENNY.
PY - 1989/1/11
Y1 - 1989/1/11
N2 - The self-splicing intervening sequence from the precursor rRNA of Tetrahymena thermophila cyclizes to form a covalently closed circle. This circle can be reopened by reaction with oligonucleotides or water. The kinetics of circle opening as a function of substrate and Mg2+ concentrations have been measured for dCrU, rCdU, dCdT, and H2O addition. Comparisons with previous results for rCrU suggest: (1) the 2' OH of the 5' sugar of a dinucleoside phosphate is involved in substrate binding, and (2) the 2' OH of the 3' sugar of a dimer substrate is involved in Mg2+ binding. Evidently, the binding site for a required Mg ion is dependent on both the ribozyme and the dimer substrate.The apparent activation energy and entropy for circle opening by hydrolysis are 31 kcal/mol and 50 eu, respectively. The large, positive activation entropy suggests a partial unfolding of the ribozyme is required for reaction.
AB - The self-splicing intervening sequence from the precursor rRNA of Tetrahymena thermophila cyclizes to form a covalently closed circle. This circle can be reopened by reaction with oligonucleotides or water. The kinetics of circle opening as a function of substrate and Mg2+ concentrations have been measured for dCrU, rCdU, dCdT, and H2O addition. Comparisons with previous results for rCrU suggest: (1) the 2' OH of the 5' sugar of a dinucleoside phosphate is involved in substrate binding, and (2) the 2' OH of the 3' sugar of a dimer substrate is involved in Mg2+ binding. Evidently, the binding site for a required Mg ion is dependent on both the ribozyme and the dimer substrate.The apparent activation energy and entropy for circle opening by hydrolysis are 31 kcal/mol and 50 eu, respectively. The large, positive activation entropy suggests a partial unfolding of the ribozyme is required for reaction.
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U2 - 10.1093/nar/17.1.355
DO - 10.1093/nar/17.1.355
M3 - Article
C2 - 2643083
AN - SCOPUS:0024966814
SN - 0305-1048
VL - 17
SP - 355
EP - 371
JO - Nucleic acids research
JF - Nucleic acids research
IS - 1
ER -