1bpn: Difference between revisions

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DIFFERENTIATION AND IDENTIFICATION OF THE TWO CATALYTIC METAL BINDING SITES IN BOVINE LENS LEUCINE AMINOPEPTIDASE BY X-RAY CRYSTALLOGRAPHY

OverviewOverview

The tightly binding and readily exchanging metal binding sites in the active site of bovine lens leucine aminopeptidase (blLAP; EC 3.4.11.1) have been differentiated and identified by x-ray crystallography. In native blLAP,Zn2+ occupies both binding sites. In solution, site 1 readily exchanges Zn2+ for other divalent cations, including Mg2+. The Zn2+ in site 2 is unavailable for metal exchange under conditions which allow exchange at site 1. The Zn2+/Mg2+ metal hybrid of blLAP (Mg-blLAP) was prepared in solution and crystallized. X-ray diffraction data to 2.9-A resolution were collected at -150 degrees C from single crystals of Mg-blLAP and native blLAP. Comparisons of omit maps calculated from the Mg-blLAP data with analogous maps calculated from the native blLAP data show electron density in one of the metal binding sites in Mg-blLAP which is much weaker than the electron density in the other binding site. Since there are fewer electrons associated with Mg2+ than with Zn2+, the difference in electron density between the two metal binding sites is consistent with occupancy of the weaker electron density site by Mg2+ and identifies this metal binding site as site 1, defined as the readily exchanging site. The present identification of the metal binding sites reverses the previous presumptive assignment of the metal binding sites which was based on the structure of native blLAP [Burley, S. K., David, P. R., Sweet, R. M., Taylor, A. & Lipscomb, W. N. (1992) J. Mol. Biol. 224, 113-140]. According to the residue-numbering convention of native blLAP, the new assignment of the metal binding sites identifies the readily exchanging site 1 with Zn-488, which is within interaction distance of one side-chain carboxylate oxygen from each of Asp-255, Asp-332, and Glu-334 and the main-chain carbonyl oxygen of Asp-332. The more tightly binding site 2 is identified with Zn-489, which is within interaction distance of one side-chain carboxylate oxygen from each of Asp-255, Asp-273, and Glu-334 and the side-chain amine nitrogen of Lys-250.

About this StructureAbout this Structure

1BPN is a Single protein structure of sequence from [1] with as ligand. Active as Leucyl aminopeptidase, with EC number 3.4.11.1 Full crystallographic information is available from OCA.

ReferenceReference

Differentiation and identification of the two catalytic metal binding sites in bovine lens leucine aminopeptidase by x-ray crystallography., Kim H, Lipscomb WN, Proc Natl Acad Sci U S A. 1993 Jun 1;90(11):5006-10. PMID:8506345

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-[[Image:1bpn.jpg|left|200px]]<br /><applet load="1bpn" size="450" color="white" frame="true" align="right" spinBox="true"
+[[Image:1bpn.jpg|left|200px]]<br /><applet load="1bpn" size="350" color="white" frame="true" align="right" spinBox="true"
 caption="1bpn, resolution 2.9&Aring;" />
 '''DIFFERENTIATION AND IDENTIFICATION OF THE TWO CATALYTIC METAL BINDING SITES IN BOVINE LENS LEUCINE AMINOPEPTIDASE BY X-RAY CRYSTALLOGRAPHY'''<br />
 ==Overview==
-The tightly binding and readily exchanging metal binding sites in the, active site of bovine lens leucine aminopeptidase (blLAP; EC 3.4.11.1), have been differentiated and identified by x-ray crystallography. In, native blLAP,Zn2+ occupies both binding sites. In solution, site 1 readily, exchanges Zn2+ for other divalent cations, including Mg2+. The Zn2+ in, site 2 is unavailable for metal exchange under conditions which allow, exchange at site 1. The Zn2+/Mg2+ metal hybrid of blLAP (Mg-blLAP) was, prepared in solution and crystallized. X-ray diffraction data to 2.9-A, resolution were collected at -150 degrees C from single crystals of, Mg-blLAP and native blLAP. Comparisons of omit maps calculated from the, Mg-blLAP data with analogous maps calculated from the native blLAP data, show electron density in one of the metal binding sites in Mg-blLAP which, is much weaker than the electron density in the other binding site. Since, there are fewer electrons associated with Mg2+ than with Zn2+, the, difference in electron density between the two metal binding sites is, consistent with occupancy of the weaker electron density site by Mg2+ and, identifies this metal binding site as site 1, defined as the readily, exchanging site. The present identification of the metal binding sites, reverses the previous presumptive assignment of the metal binding sites, which was based on the structure of native blLAP [Burley, S. K., David, P., R., Sweet, R. M., Taylor, A. &amp; Lipscomb, W. N. (1992) J. Mol. Biol. 224, 113-140]. According to the residue-numbering convention of native blLAP, the new assignment of the metal binding sites identifies the readily, exchanging site 1 with Zn-488, which is within interaction distance of one, side-chain carboxylate oxygen from each of Asp-255, Asp-332, and Glu-334, and the main-chain carbonyl oxygen of Asp-332. The more tightly binding, site 2 is identified with Zn-489, which is within interaction distance of, one side-chain carboxylate oxygen from each of Asp-255, Asp-273, and, Glu-334 and the side-chain amine nitrogen of Lys-250.
+The tightly binding and readily exchanging metal binding sites in the active site of bovine lens leucine aminopeptidase (blLAP; EC 3.4.11.1) have been differentiated and identified by x-ray crystallography. In native blLAP,Zn2+ occupies both binding sites. In solution, site 1 readily exchanges Zn2+ for other divalent cations, including Mg2+. The Zn2+ in site 2 is unavailable for metal exchange under conditions which allow exchange at site 1. The Zn2+/Mg2+ metal hybrid of blLAP (Mg-blLAP) was prepared in solution and crystallized. X-ray diffraction data to 2.9-A resolution were collected at -150 degrees C from single crystals of Mg-blLAP and native blLAP. Comparisons of omit maps calculated from the Mg-blLAP data with analogous maps calculated from the native blLAP data show electron density in one of the metal binding sites in Mg-blLAP which is much weaker than the electron density in the other binding site. Since there are fewer electrons associated with Mg2+ than with Zn2+, the difference in electron density between the two metal binding sites is consistent with occupancy of the weaker electron density site by Mg2+ and identifies this metal binding site as site 1, defined as the readily exchanging site. The present identification of the metal binding sites reverses the previous presumptive assignment of the metal binding sites which was based on the structure of native blLAP [Burley, S. K., David, P. R., Sweet, R. M., Taylor, A. &amp; Lipscomb, W. N. (1992) J. Mol. Biol. 224, 113-140]. According to the residue-numbering convention of native blLAP, the new assignment of the metal binding sites identifies the readily exchanging site 1 with Zn-488, which is within interaction distance of one side-chain carboxylate oxygen from each of Asp-255, Asp-332, and Glu-334 and the main-chain carbonyl oxygen of Asp-332. The more tightly binding site 2 is identified with Zn-489, which is within interaction distance of one side-chain carboxylate oxygen from each of Asp-255, Asp-273, and Glu-334 and the side-chain amine nitrogen of Lys-250.
 ==About this Structure==
-BPN is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/ ] with ZN as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Leucyl_aminopeptidase Leucyl aminopeptidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.4.11.1 3.4.11.1] Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1BPN OCA].
+BPN is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/ ] with <scene name='pdbligand=ZN:'>ZN</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Leucyl_aminopeptidase Leucyl aminopeptidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.4.11.1 3.4.11.1] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1BPN OCA].
 ==Reference==
@@ Line 14: / Line 14: @@
 [[Category: Single protein]]
 [[Category: Kim, H.]]
-[[Category: Lipscomb, W.N.]]
+[[Category: Lipscomb, W N.]]
 [[Category: ZN]]
 [[Category: hydrolase(alpha-aminoacylpeptide)]]
-''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Tue Nov 20 11:49:10 2007''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 11:57:45 2008''