1hfy
From Proteopedia
(New page: 200px<br /><applet load="1hfy" size="450" color="white" frame="true" align="right" spinBox="true" caption="1hfy, resolution 2.3Å" /> '''ALPHA-LACTALBUMIN'''<...) |
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| - | [[Image:1hfy.gif|left|200px]]<br /><applet load="1hfy" size=" | + | [[Image:1hfy.gif|left|200px]]<br /><applet load="1hfy" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1hfy, resolution 2.3Å" /> | caption="1hfy, resolution 2.3Å" /> | ||
'''ALPHA-LACTALBUMIN'''<br /> | '''ALPHA-LACTALBUMIN'''<br /> | ||
==Overview== | ==Overview== | ||
| - | BACKGROUND: The regulation of milk lactose biosynthesis is highly | + | BACKGROUND: The regulation of milk lactose biosynthesis is highly dependent on the action of a specifier protein, alpha-lactalbumin (LA). Together with a glycosyltransferase, LA forms the enzyme complex lactose synthase. LA promotes the binding of glucose to the complex and facilitates the biosynthesis of lactose. To gain further insight into the molecular basis of LA function in lactose synthase we have determined the structures of three species variants of LA. RESULTS: The crystal structures of guinea-pig, goat and a recombinant from of bovine LA have been determined using molecular replacement techniques. Overall, the structures are very similar and reflect their high degree of amino acid sequence identity (66-94%). Nonetheless, the structures show that a portion of the molecule (residues 105-110), known to be important for function, exhibits a variety of distinct conformers. This region lies adjacent to two residues (Phe31 and His32) that have been implicated in monosaccharide binding by lactose synthase and its conformation has significant effects on the environments of these functional groups. The crystal structures also demonstrate that residues currently implicated in LA's modulatory properties are located in a region of the structure that has relatively high thermal parameters and is therefore probably flexible in vivo. CONCLUSIONS: LA's proposed interaction site for the catalytic component of the lactose synthase complex is primarily located in the flexible C-terminal portion of the molecule. This general observation implies that conformational adjustments may be important for the formation and function of lactose synthase. |
==About this Structure== | ==About this Structure== | ||
| - | 1HFY is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Capra_hircus Capra hircus] with CA as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Lactose_synthase Lactose synthase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.4.1.22 2.4.1.22] Full crystallographic information is available from [http:// | + | 1HFY is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Capra_hircus Capra hircus] with <scene name='pdbligand=CA:'>CA</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Lactose_synthase Lactose synthase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.4.1.22 2.4.1.22] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1HFY OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Lactose synthase]] | [[Category: Lactose synthase]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Acharya, K | + | [[Category: Acharya, K R.]] |
[[Category: Brew, K.]] | [[Category: Brew, K.]] | ||
| - | [[Category: Pike, A | + | [[Category: Pike, A C.W.]] |
[[Category: CA]] | [[Category: CA]] | ||
[[Category: calcium binding metalloprotein]] | [[Category: calcium binding metalloprotein]] | ||
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[[Category: lactose synthase component]] | [[Category: lactose synthase component]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:00:52 2008'' |
Revision as of 11:00, 21 February 2008
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ALPHA-LACTALBUMIN
Overview
BACKGROUND: The regulation of milk lactose biosynthesis is highly dependent on the action of a specifier protein, alpha-lactalbumin (LA). Together with a glycosyltransferase, LA forms the enzyme complex lactose synthase. LA promotes the binding of glucose to the complex and facilitates the biosynthesis of lactose. To gain further insight into the molecular basis of LA function in lactose synthase we have determined the structures of three species variants of LA. RESULTS: The crystal structures of guinea-pig, goat and a recombinant from of bovine LA have been determined using molecular replacement techniques. Overall, the structures are very similar and reflect their high degree of amino acid sequence identity (66-94%). Nonetheless, the structures show that a portion of the molecule (residues 105-110), known to be important for function, exhibits a variety of distinct conformers. This region lies adjacent to two residues (Phe31 and His32) that have been implicated in monosaccharide binding by lactose synthase and its conformation has significant effects on the environments of these functional groups. The crystal structures also demonstrate that residues currently implicated in LA's modulatory properties are located in a region of the structure that has relatively high thermal parameters and is therefore probably flexible in vivo. CONCLUSIONS: LA's proposed interaction site for the catalytic component of the lactose synthase complex is primarily located in the flexible C-terminal portion of the molecule. This general observation implies that conformational adjustments may be important for the formation and function of lactose synthase.
About this Structure
1HFY is a Single protein structure of sequence from Capra hircus with as ligand. Active as Lactose synthase, with EC number 2.4.1.22 Full crystallographic information is available from OCA.
Reference
Crystal structures of guinea-pig, goat and bovine alpha-lactalbumin highlight the enhanced conformational flexibility of regions that are significant for its action in lactose synthase., Pike AC, Brew K, Acharya KR, Structure. 1996 Jun 15;4(6):691-703. PMID:8805552
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