1n1x: Difference between revisions

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Crystal Structure Analysis of the monomeric [S-carboxyamidomethyl-Cys31, S-carboxyamidomethyl-Cys32] Bovine seminal ribonuclease

OverviewOverview

Bovine seminal ribonuclease, a homodimeric enzyme joined covalently by two interchain disulphide bonds, is an equilibrium mixture of two conformational isomers, MxM and M=M. The major form, MxM, whose crystal structure has been previously determined at 1.9 A resolution, presents the swapping of the N-terminal segments (residues 1-15) and composite active sites formed by residues of different chains. The three-dimensional domain swapping does not occur in the M=M form. The different fold of each N-terminal tail is directed by the hinge loop (residue 16-22) connecting the swapping domain to the body of the protein. Reduction and alkylation of interchain disulphide bridges produce a monomeric derivative and a noncovalent swapped dimer, which are both active. The free and nucleotide-bound forms of the monomer have been crystallized at an alkaline pH and refined at 1.45 and 1.65 A resolution, respectively. In both cases, the N-terminal fragment is folded on the main body of the protein to produce an intact active site and a chain architecture very similar to that of bovine pancreatic ribonuclease. In this new fold of the seminal chain, the hinge loop is disordered. Despite the difference between the tertiary structure of the monomer and that of the chains in the MxM form, the active sites of the two enzymes are virtually indistinguishable. Furthermore, the structure of the liganded enzyme represents the first example of a ribonuclease complex studied at an alkaline pH and provides new information on the binding of a nucleotide when the catalytic histidines are deprotonated.

About this StructureAbout this Structure

1N1X is a Single protein structure of sequence from Bos taurus. Active as Pancreatic ribonuclease, with EC number 3.1.27.5 Full crystallographic information is available from OCA.

ReferenceReference

The unswapped chain of bovine seminal ribonuclease: Crystal structure of the free and liganded monomeric derivative., Sica F, Di Fiore A, Zagari A, Mazzarella L, Proteins. 2003 Aug 1;52(2):263-71. PMID:12833549

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 '''Crystal Structure Analysis of the monomeric [S-carboxyamidomethyl-Cys31, S-carboxyamidomethyl-Cys32] Bovine seminal ribonuclease'''<br />
 ==Overview==
-Bovine seminal ribonuclease, a homodimeric enzyme joined covalently by two, interchain disulphide bonds, is an equilibrium mixture of two, conformational isomers, MxM and M=M. The major form, MxM, whose crystal, structure has been previously determined at 1.9 A resolution, presents the, swapping of the N-terminal segments (residues 1-15) and composite active, sites formed by residues of different chains. The three-dimensional domain, swapping does not occur in the M=M form. The different fold of each, N-terminal tail is directed by the hinge loop (residue 16-22) connecting, the swapping domain to the body of the protein. Reduction and alkylation, of interchain disulphide bridges produce a monomeric derivative and a, noncovalent swapped dimer, which are both active. The free and, nucleotide-bound forms of the monomer have been crystallized at an, alkaline pH and refined at 1.45 and 1.65 A resolution, respectively. In, both cases, the N-terminal fragment is folded on the main body of the, protein to produce an intact active site and a chain architecture very, similar to that of bovine pancreatic ribonuclease. In this new fold of the, seminal chain, the hinge loop is disordered. Despite the difference, between the tertiary structure of the monomer and that of the chains in, the MxM form, the active sites of the two enzymes are virtually, indistinguishable. Furthermore, the structure of the liganded enzyme, represents the first example of a ribonuclease complex studied at an, alkaline pH and provides new information on the binding of a nucleotide, when the catalytic histidines are deprotonated.
+Bovine seminal ribonuclease, a homodimeric enzyme joined covalently by two interchain disulphide bonds, is an equilibrium mixture of two conformational isomers, MxM and M=M. The major form, MxM, whose crystal structure has been previously determined at 1.9 A resolution, presents the swapping of the N-terminal segments (residues 1-15) and composite active sites formed by residues of different chains. The three-dimensional domain swapping does not occur in the M=M form. The different fold of each N-terminal tail is directed by the hinge loop (residue 16-22) connecting the swapping domain to the body of the protein. Reduction and alkylation of interchain disulphide bridges produce a monomeric derivative and a noncovalent swapped dimer, which are both active. The free and nucleotide-bound forms of the monomer have been crystallized at an alkaline pH and refined at 1.45 and 1.65 A resolution, respectively. In both cases, the N-terminal fragment is folded on the main body of the protein to produce an intact active site and a chain architecture very similar to that of bovine pancreatic ribonuclease. In this new fold of the seminal chain, the hinge loop is disordered. Despite the difference between the tertiary structure of the monomer and that of the chains in the MxM form, the active sites of the two enzymes are virtually indistinguishable. Furthermore, the structure of the liganded enzyme represents the first example of a ribonuclease complex studied at an alkaline pH and provides new information on the binding of a nucleotide when the catalytic histidines are deprotonated.
 ==About this Structure==
-N1X is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bos_taurus Bos taurus]. Active as [http://en.wikipedia.org/wiki/Pancreatic_ribonuclease Pancreatic ribonuclease], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.1.27.5 3.1.27.5] Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1N1X OCA].
+N1X is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bos_taurus Bos taurus]. Active as [http://en.wikipedia.org/wiki/Pancreatic_ribonuclease Pancreatic ribonuclease], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.1.27.5 3.1.27.5] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1N1X OCA].
 ==Reference==
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 [[Category: Pancreatic ribonuclease]]
 [[Category: Single protein]]
-[[Category: Fiore, A.Di.]]
+[[Category: Fiore, A Di.]]
 [[Category: Mazzarella, L.]]
 [[Category: Sica, F.]]
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 [[Category: hydrolase]]
-''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Tue Nov 20 21:52:44 2007''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 14:01:19 2008''