Sandbox Reserved 779: Difference between revisions

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=='''Molecular mechanism of the Tanford transition'''==

The Tanford transition is a conformational change of bovine β-lactoglobulin occurring at around pH 7, identified originally on the basis of optical rotatory dispersion and the accessibility of a thiol group. X-ray analysis has suggested that a conformational change to the EF-loop is responsible for the Tanford transition, with the loop closing the hydrophobic cavity of the β-barrel of the β-LG molecule below pH 7 and flipping to open the cavity above pH 7.<ref>PMID:16368109</ref>Tanford transition is triggered by protonation of Glu89 exhibiting an anomalously high pKa value. The Tanford transition involves displacement/conformational change of the loop EF (residues 85 to 90) that acts as a lid which closes the protein interior/binding site below pH 7.3 and opens it at higher pH. The Tanford transition may involve some other structural changes as well. For example, the transition is accompanied by a change in the microenvironment of ~~Tyr428~~ and causes an alteration in the relative orientation of monomers in the dimer by as much as 5 degrees, which breaks a number of intersubunit hydrogen bonds. It should be noted that all transitions that take place between pH 2 and pH 9 do not cause any appreciable changes in the native like β-barrel conformation of β-lactoglobulin.

The Tanford transition is a conformational change of bovine β-lactoglobulin occurring at around pH 7, identified originally on the basis of optical rotatory dispersion and the accessibility of a thiol group. X-ray analysis has suggested that a conformational change to the EF-loop is responsible for the Tanford transition, with the loop closing the hydrophobic cavity of the β-barrel of the β-LG molecule below pH 7 and flipping to open the cavity above pH 7.<ref>PMID:16368109</ref>Tanford transition is triggered by protonation of Glu89 exhibiting an anomalously high pKa value. The Tanford transition involves displacement/conformational change of the loop EF (residues 85 to 90) that acts as a lid which closes the protein interior/binding site below pH 7.3 and opens it at higher pH. The Tanford transition may involve some other structural changes as well. For example, the transition is accompanied by a change in the microenvironment of Tyr42 and causes an alteration in the relative orientation of monomers in the dimer by as much as 5 degrees, which breaks a number of intersubunit hydrogen bonds. It should be noted that all transitions that take place between pH 2 and pH 9 do not cause any appreciable changes in the native like β-barrel conformation of β-lactoglobulin.

Sandbox Reserved 779: Difference between revisions

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 =='''Molecular mechanism of the Tanford transition'''==
-The Tanford transition is a conformational change of bovine β-lactoglobulin occurring at around pH 7, identified originally on the basis of optical rotatory dispersion and the accessibility of a thiol group. X-ray analysis has suggested that a conformational change to the EF-loop is responsible for the Tanford transition, with the loop closing the hydrophobic cavity of the β-barrel of the β-LG molecule below pH 7 and flipping to open the cavity above pH 7.<ref>PMID:16368109</ref>Tanford transition is triggered by protonation of Glu89 exhibiting an anomalously high pKa value. The Tanford transition involves displacement/conformational change of the loop EF (residues 85 to 90) that acts as a lid which closes the protein interior/binding site below pH 7.3 and opens it at higher pH. The Tanford transition may involve some other structural changes as well. For example, the transition is accompanied by a change in the microenvironment of Tyr428 and causes an alteration in the relative orientation of monomers in the dimer by as much as 5 degrees, which breaks a number of intersubunit hydrogen bonds. It should be noted that all transitions that take place between pH 2 and pH 9 do not cause any appreciable changes in the native like β-barrel conformation of β-lactoglobulin.
+The Tanford transition is a conformational change of bovine β-lactoglobulin occurring at around pH 7, identified originally on the basis of optical rotatory dispersion and the accessibility of a thiol group. X-ray analysis has suggested that a conformational change to the EF-loop is responsible for the Tanford transition, with the loop closing the hydrophobic cavity of the β-barrel of the β-LG molecule below pH 7 and flipping to open the cavity above pH 7.<ref>PMID:16368109</ref>Tanford transition is triggered by protonation of Glu89 exhibiting an anomalously high pKa value. The Tanford transition involves displacement/conformational change of the loop EF (residues 85 to 90) that acts as a lid which closes the protein interior/binding site below pH 7.3 and opens it at higher pH. The Tanford transition may involve some other structural changes as well. For example, the transition is accompanied by a change in the microenvironment of Tyr42 and causes an alteration in the relative orientation of monomers in the dimer by as much as 5 degrees, which breaks a number of intersubunit hydrogen bonds. It should be noted that all transitions that take place between pH 2 and pH 9 do not cause any appreciable changes in the native like β-barrel conformation of β-lactoglobulin.
 <ref>PMID:11734004</ref>