| Autor: |
D, Smith, A B, Burgin, E S, Haas, N R, Pace |
| Rok vydání: |
1992 |
| Předmět: |
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| Zdroj: |
The Journal of biological chemistry. 267(4) |
| ISSN: |
0021-9258 |
| Popis: |
A high yield, photoactivated cross-linking reaction between a modified tRNA and RNase P RNA was used as a quantitative assay of substrate binding affinity. The cross-linking assay allows the effects of metal ions on substrate binding to be measured independently and in the absence of the pre-tRNA cleavage reaction. The results of this assay, in conjunction with the conventional cleavage assay, support the following conclusions about the nature of the RNase P RNA-tRNA binding interaction. (i) Monovalent cations act primarily to enhance enzyme-substrate binding, presumably by functioning as counterions. This enhancement can be attributed to a reduction in the tRNA off-rate. (ii) Although divalent cation is required for cleavage, the enzyme-substrate complex can form in the absence of divalent cation; the essential role of divalent cation in the reaction is thus catalytic. (iii) Ca2+ is as efficient as Mg2+ in promoting binding but supports catalysis only at a low rate. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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