Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.27.3 (RNase T1)
 1,228 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Three different fragments of Bacillus megaterium ribosomal 5S RNA have been produced by enzymatic cleavage with ribonuclease T1. Fragment A consists of helices II and III, fragment B contains helix IV, and fragment C contains helix I of the universal 5S rRNA secondary structure. All (eight) imino proton resonances in the downfield region (9-15 ppm) of the 500-MHz proton FT NMR spectrum of fragment B have been identified and assigned as G80.C92-G81.C91-G82.C90-A83.++ +U89-C84.G88 and three unpaired U's (U85, U86, and U87) in helix IV by proton homonuclear Overhauser enhancement connectivities. The secondary structure in helix IV of the prokaryotic loop is completely demonstrated spectroscopically for the first time in any native or enzyme-cleaved 5S rRNA. In addition, G21.C58-A20.U59-G19.C60-A18.U61 in helix II, U32.A46-G31.C47-C30.G48-C29.G49 in helix III, and G4.C112-G5.C111-U6.G110 in the terminal stem (helix I) have been assigned by means of NOE experiments on intact 5S rRNA and its fragments A and C. Base pairs in helices I-IV of the universal secondary structure of B. megaterium 5S RNA are described.
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PMID:Identification and assignment of base pairs in four helical segments of Bacillus megaterium ribosomal 5S RNA and its ribonuclease T1 cleavage fragments by means of 500-MHz proton homonuclear Overhauser enhancements. 169 78

The enzyme peptidylprolyl cis-trans isomerase (PPI) is known to catalyze proline isomerization in short proline-containing peptides. If PPI can be shown to generally catalyze isomerization of proline residues in proteins, then it would be a valuable diagnostic reagent for recognition of isomerization, which has proven to be extremely difficult to characterize by other methods. In this study, the catalytic effect of PPI on the slow refolding reactions of seven different proteins has been studied, and in only two cases (RNase T1 and cytochrome c) could significant catalysis be seen. PPI also caused no enhancement in the rate for the 'subtle' conformational changes of native concanavalin A or native Fragment I of prothrombin, which have been suggested to be rate-limited by proline isomerization. There was a small effect of PPI observed for the generation of native RNAase A from the fully-reduced form when the glutathione concentration was low. The conclusion from these studies is that PPI can weakly catalyze some protein processes which are rate-limited by proline isomerization, but probably exhibits no measureable catalysis toward others. This somewhat limits the usefulness of PPI as a diagnostic reagent for proline isomerization.
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PMID:Catalysis of proline isomerization during protein-folding reactions. 304 13

The reagent 4'-(hydroxymethyl)-4,5',8-trimethylpsoralen (HMT) was used to cross-link 23S rRNA from Escherichia coli under 50S ribosomal subunit reconstitution conditions. Following partial digestion of the RNA with ribonuclease T1, two-dimensional diagonal electrophoresis in denaturing polyacrylamide gels was used to isolate fragments derived from the cross-linked sites. These fragments were analyzed by digestion with ribonucleases T1 and A and their positions in the 23S RNA sequence identified. Fragment a1 (positions 1325-1426) is cross-linked to a2 (positions 1574-1623); fragment b1 (positions 1700-1731) is cross-linked to b2 (positions 1732-1753); and a cross-link is formed within fragment c (or c') (positions 863-916). In the latter case, the cross-link was located precisely, linking residues C867 and U913. All three HMT-mediated cross-links are consistent with a proposed secondary structure model for 23S RNA [Noller, H. F., Kop, J., Wheaton, V., Brosius, J., Gutell, R. R., Kopylov, A. M., Dohme, F., Herr, W., Stahl, D. A., Gupta, R., & Woese, C. R. (1981) Nucleic Acids Res. 9, 6167-6189].
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PMID:Identification of sites of 4'-(hydroxymethyl)-4,5',8-trimethylpsoralen cross-linking in Escherichia coli 23S ribosomal ribonucleic acid. 635 17