1ssb
From Proteopedia
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[[Image:1ssb.gif|left|200px]] | [[Image:1ssb.gif|left|200px]] | ||
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'''A STRUCTURAL INVESTIGATION OF CATALYTICALLY MODIFIED F12OL AND F12OY SEMISYNTHETIC RIBONUCLEASES''' | '''A STRUCTURAL INVESTIGATION OF CATALYTICALLY MODIFIED F12OL AND F12OY SEMISYNTHETIC RIBONUCLEASES''' | ||
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==About this Structure== | ==About this Structure== | ||
| - | 1SSB is a [[Protein complex]] structure | + | 1SSB is a [[Protein complex]] structure. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1SSB OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Martin, P D.]] | [[Category: Martin, P D.]] | ||
[[Category: Ram, M L.]] | [[Category: Ram, M L.]] | ||
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Revision as of 06:05, 3 May 2008
A STRUCTURAL INVESTIGATION OF CATALYTICALLY MODIFIED F12OL AND F12OY SEMISYNTHETIC RIBONUCLEASES
Overview
The structures of two catalytically modified semisynthetic RNases obtained by replacing phenylalanine 120 with leucine and tyrosine have been determined and refined at a resolution of 2.0 A (R = 0.161 and 0.184, respectively). These structures have been compared with the refined 1.8-A structure (R = 0.204) of the fully active phenylalanine-containing enzyme (Martin PD, Doscher MS, Edwards BFP, 1987, J Biol Chem 262:15930-15938) and with the catalytically defective D121A (2.0 A, R = 0.172) and D121N (2.0 A, R = 0.186) analogs (deMel VSJ, Martin PD, Doscher MS, Edwards BFP, 1992, J Biol Chem 267:247-256). The movement away from the active site of the loop containing residues 65-72 is seen in all three catalytically defective analogs--F120L, D121A, and D121N--but not in the fully active (or hyperactive) F120Y. The insertion of the phenolic hydroxyl of Tyr 120 into a hydrogen-bonding network involving the hydroxyl group of Ser 123 and a water molecule in F120Y is the likely basis for the hyperactivity toward uridine 2',3'-cyclic phosphate previously found for this analog (Hodges RS, Merrifield RB, 1974, Int J Pept Protein Res 6:397-405) as well as the threefold increase in KM for cytidine 2',3'-cyclic phosphate found for this analog by ourselves.
About this Structure
1SSB is a Protein complex structure. Full crystallographic information is available from OCA.
Reference
Structural investigation of catalytically modified F120L and F120Y semisynthetic ribonucleases., deMel VS, Doscher MS, Glinn MA, Martin PD, Ram ML, Edwards BF, Protein Sci. 1994 Jan;3(1):39-50. PMID:8142897 Page seeded by OCA on Sat May 3 09:05:06 2008
