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| [[Image:1q9e.gif|left|200px]] | | {{Seed}} |
| | [[Image:1q9e.png|left|200px]] |
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| {{STRUCTURE_1q9e| PDB=1q9e | SCENE= }} | | {{STRUCTURE_1q9e| PDB=1q9e | SCENE= }} |
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| '''RNase T1 variant with adenine specificity'''
| | ===RNase T1 variant with adenine specificity=== |
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| ==Overview==
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| Attempts to alter the guanine specificity of ribonuclease T1 (RNase T1) by rational or random mutagenesis have failed so far. The RNase T1 variant RV (Lys41Glu, Tyr42Phe, Asn43Arg, Tyr45Trp, and Glu46Asn) designed by combination of a random and a rational mutagenesis approach, however, exhibits a stronger preference toward adenosine residues than wild-type RNase T1. Steady state kinetics of the cleavage reaction of the two dinucleoside phosphate substrates adenylyl-3',5'-cytidine and guanylyl-3',5'-cytidine revealed that the ApC/GpC ratio of the specificity coefficient (k(cat)/K(m)) was increased approximately 7250-fold compared to that of the wild-type. The crystal structure of the nucleotide-free RV variant has been refined in space group P6(1) to a crystallographic R-factor of 19.9% at 1.7 A resolution. The primary recognition site of the RV variant adopts a similar conformation as already known from crystal structures of RNase T1 not complexed to any nucleotide. Noteworthy is a high flexibility of Trp45 and Asn46 within the three individual molecules in the asymmetric unit. In addition to the kinetic studies, these data indicate the participation of Asn46 in the specific recognition of the base and therefore a specific binding of adenosine.
| | The line below this paragraph, {{ABSTRACT_PUBMED_15005620}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 15005620 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_15005620}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Hydrolase]] | | [[Category: Hydrolase]] |
| [[Category: Ribonuclease]] | | [[Category: Ribonuclease]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 06:01:56 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 14:29:17 2008'' |
