Sandbox Reserved 779: Difference between revisions
From Proteopedia
Jump to navigationJump to search
Rini Triani (talk | contribs) No edit summary |
Rini Triani (talk | contribs) No edit summary |
||
| Line 36: | Line 36: | ||
== Structure of β-Lactoglobulin == | =='''Structure of β-Lactoglobulin'''== | ||
===Residues and secondary structures=== | ===Residues and secondary structures=== | ||
| Line 63: | Line 63: | ||
==Molecular mechanism of the Tanford transition== | =='''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 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. | ||
| Line 72: | Line 72: | ||
==Implications or possible application== | =='''Implications or possible application'''== | ||
β-LG interaction with hydrophobic molecules and with other proteins, and its sensitivity to chemical, thermal and baric denaturation, all with a view to establishing relationships among structure, properties and functionality | β-LG interaction with hydrophobic molecules and with other proteins, and its sensitivity to chemical, thermal and baric denaturation, all with a view to establishing relationships among structure, properties and functionality | ||
| Line 86: | Line 86: | ||
vehicle to transport molecules to the gut | vehicle to transport molecules to the gut | ||
==External Sources== | =='''External Sources'''== | ||
.... | .... | ||
==Other β-Lactoglobulin related 3D Structures and complexes== | =='''Other β-Lactoglobulin related 3D Structures and complexes'''== | ||
[[2q2m]] - Bovine β-Lactoglobulin Native (Fig. 4) | [[2q2m]] - Bovine β-Lactoglobulin Native (Fig. 4) | ||
