1vfd

From Proteopedia

Revision as of 15:13, 5 November 2007

HUMAN LACTOFERRIN, N-TERMINAL LOBE MUTANT WITH ARG 121 REPLACED BY GLU (R121E)

Overview

A conserved arginine residue helps to form the synergistic anion binding, site in transferrins. To probe the importance of this residue for anion, binding and iron binding, Arg 121 has been mutated to Ser and Glu in, N-terminal half-molecule of human lactoferrin. The two mutants, R121S and, R121E, have been expressed, purified, and crystallized. Their, three-dimensional structures have been determined by X-ray diffraction at, 2.3 and 2.5 A resolution, respectively. The structures were determined by, molecular replacement and were refined by restrained least squares methods, to final R values of 0.185 and 0.204. Both mutants still bind iron but, with decreased stability. The crystal structures show that destabilization, of iron binding probably results from disruption of the anion binding, site; mutation of Arg 121 removes one wall of the anion binding pocket and, causes the synergistic carbonate ion to be displaced 0.5 A from its, position in the wild-type protein. In the process it becomes partially, detached from the helix N-terminus that forms the rest of the anion, binding site.

About this Structure

1VFD is a Single protein structure of sequence from Homo sapiens with FE and CO3 as ligands. Structure known Active Site: BST. Full crystallographic information is available from OCA.

Reference

Mutation of arginine 121 in lactoferrin destabilizes iron binding by disruption of anion binding: crystal structures of R121S and R121E mutants., Faber HR, Baker CJ, Day CL, Tweedie JW, Baker EN, Biochemistry. 1996 Nov 19;35(46):14473-9. PMID:8931543

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