1i4n
From Proteopedia
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CRYSTAL STRUCTURE OF INDOLEGLYCEROL PHOSPHATE SYNTHASE FROM THERMOTOGA MARITIMA
Overview
The crystal structure of the thermostable indoleglycerol-phosphate, synthase from Thermotoga maritima (tIGPS) was determined at 2.5 A, resolution. It was compared with the structures of the thermostable sIGPS, from Sulfolobus solfataricus and of the thermolabile eIGPS from, Escherichia coli. The main chains of the three (beta alpha)(8)-barrel, proteins superimpose closely, and the packing of side chains in the, beta-barrel cores, as well as the architecture of surface loops, is very, similar. Both thermostable proteins have, however, 17 strong salt bridges, compared with only 10 in eIGPS. The number of additional salt bridges in, tIGPS and sIGPS correlates well with their reduced rate of irreversible, thermal inactivation at 90 degrees C. Only 3 of 17 salt bridges in tIGPS, and sIGPS are topologically conserved. The major difference between the, two proteins is the preference for interhelical salt bridges in sIGPS and, intrahelical ones in tIGPS. The different implementation of salt bridges, in the closely related proteins suggests that the stabilizing effect of, salt bridges depends rather on the sum of their individual contributions, than on their location. This observation is consistent with a protein, unfolding mechanism where the simultaneous breakdown of all salt bridges, is the rate-determining step.
About this Structure
1I4N is a Single protein structure of sequence from Thermotoga maritima with SO4 as ligand. Active as Indole-3-glycerol-phosphate synthase, with EC number 4.1.1.48 Full crystallographic information is available from OCA.
Reference
The crystal structure of indoleglycerol-phosphate synthase from Thermotoga maritima. Kinetic stabilization by salt bridges., Knochel T, Pappenberger A, Jansonius JN, Kirschner K, J Biol Chem. 2002 Mar 8;277(10):8626-34. Epub 2001 Dec 10. PMID:11741953
Page seeded by OCA on Tue Nov 20 17:02:53 2007
