1c8w

<table><tr><td colspan='2'>[[1c8w]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Bovin Bovin]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1C8W OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1C8W FirstGlance]. <br>

</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=ACT:ACETATE+ION'>ACT</scene>, <scene name='pdbligand=CL:CHLORIDE+ION'>CL</scene></td></tr>

[[https://www.uniprot.org/uniprot/RNAS1_BOVIN RNAS1_BOVIN]] Endonuclease that catalyzes the cleavage of RNA on the 3' side of pyrimidine nucleotides. Acts on single stranded and double stranded RNA.<ref>PMID:7479688</ref>

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== Publication Abstract from PubMed ==

Ribonuclease A (RNase A) catalyzes the cleavage of RNA after pyrimidine nucleotides. When bound in the active site, the base of a pyrimidine nucleotide forms hydrogen bonds with the side chain of Thr45. Here, the role of Thr45 was probed by using the wild-type enzyme, its T45G variant, X-ray diffraction analysis, and synthetic oligonucleotides as ligands and substrates. Catalytic specificity was determined with the fluorogenic substrate: 6-carboxyfluorescein approximately dArXdAdA approximately 6-carboxytetramethylrhodamine (6-FAM approximately dArXdAdA approximately 6-TAMRA), where X = C, U, A, or G. Wild-type RNase A cleaves 10(6)-fold faster when X = C than when X = A. Likewise, its affinity for the non-hydrolyzable oligonucleotide 6-FAM approximately d(CAA) is 50-fold greater than for 6-FAM approximately d(AAA). T45G RNase A cleaves 6-FAM approximately dArAdAdA approximately 6-TAMRA 10(2)-fold faster than does the wild-type enzyme. The structure of crystalline T45G RNase A, determined at 1.8-A resolution by X-ray diffraction analysis, does not reveal new potential interactions with a nucleobase. Indeed, the two enzymes have a similar affinity for 6-FAM approximately d(AAA). The importance of pentofuranosyl ring conformation to nucleotide specificity was probed with 6-FAM approximately d(AU(F)AA), where U(F) is 2'-deoxy-2'-fluorouridine. The conformation of the pentofuranosyl ring in dU(F) is known to be more similar to that in rU than dU. The affinity of wild-type RNase A for 6-FAM approximately d(AU(F)AA) is 50-fold lower than for 6-FAM approximately d(AUAA). This discrimination is lost in the T45G enzyme. Together, these data indicate that the side chain of Thr45 plays multiple roles-interacting favorably with pyrimidine nucleobases but unfavorably with purine nucleobases. Moreover, a ribose-like ring disfavors the interaction of Thr45 with a pyrimidine nucleobase, suggesting that Thr45 enhances catalysis by ground-state destabilization.

Excavating an active site: the nucleobase specificity of ribonuclease A.,Kelemen BR, Schultz LW, Sweeney RY, Raines RT Biochemistry. 2000 Nov 28;39(47):14487-94. PMID:11087402<ref>PMID:11087402</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>

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<div class="pdbe-citations 1c8w" style="background-color:#fffaf0;"></div>

[[Category: Bovin]]

[[Category: Kelemen, B R]]

[[Category: Raines, R T]]

[[Category: Schultz, L W]]

[[Category: Sweeney, R T]]

[[Category: Rnase some]]