1iyy: Difference between revisions

[[Image:1iyy.jpg|left|200px]]<br /><applet load="1iyy" size="350" color="white" frame="true" align="right" spinBox="true"  

Ribonuclease (RNase) T1 is a guanyloribonuclease, having two isozymes in nature, Gln25- and Lys25-RNase T1. Between these two isozymes, there is no difference in catalytic activity and three-dimensional structure; however, Lys25-RNase T1 is slightly more stable than Gln25-RNase T1. Recently, it has been suggested that the existence of a salt bridge between Lys25 and Asp29/Glu31 in Lys25-RNase T1 contributes to the stability. To elucidate the effects of the replacement of Lys25 with a Gln on the conformation and microenvironments of RNase T1 in detail, the three-dimensional solution structure of Gln25-RNase T1 was determined by simulated-annealing calculations. As a result, the topology of the overall folding was shown to be very similar to that of the Lys25-isozyme except for some differences. In particular, there were two differences in the property of torsion angles of the two disulfide bonds and the conformations of the residues 11-13, 63-66, and 92-93. With regard to the residues 11-13, the lack of the above-mentioned salt bridge in Gln25-RNase T1 was thought to induce the conformational difference of this segment as compared with the Lys25-isozyme. Furthermore, it was proposed that the perturbation of this segment might transfer to the residues 92-93 via the two disulfide bonds.

1IYY is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Aspergillus_oryzae Aspergillus oryzae]. Active as [http://en.wikipedia.org/wiki/Ribonuclease_T(1) Ribonuclease T(1)], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.1.27.3 3.1.27.3] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1IYY OCA].  

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