Reversible and irreversible unfolding of eukaryote chromosomes by force

Author(s):  
J.F. Marko ◽  
M. Poirier ◽  
S. Eroglu ◽  
D. Chatenay
1981 ◽  
Vol 197 (1) ◽  
pp. 105-109 ◽  
Author(s):  
D R Thatcher ◽  
B Hodson

A polyacrylamide-gel-electrophoresis method has been developed that permits the analysis of conformational changes that occur during the thermal denaturation of macromolecules. A stable transverse temperature gradient was produced in an aluminium heating jacket clamped around a vertical polyacrylamide slab gel. After temperature equilibration, gels were loaded with either a layer of protein solution (20-200 micrograms/gel) or a solution of double-stranded DNA (20 micrograms/gel) and electrophoresis begun. At the end of the run the gels were stained and the effect of temperature on mobility observed. The technique proved informative both for the irreversible unfolding of proteins (Drosophila alcohol dehydrogenase and lactic acid dehydrogenase) and for a protein that was reversibly denatured by heat (beta-lactamase). In the latter case a clear transition between the native enzyme and a slower-migrating denatured state was observed. The patterns obtained were analogous to the type produced by the transverse-urea-gradient-electrophoretic method of Creighton [(1979) J. Mol. Biol. 129, 253-264]. The method also resolved a complex mixture of double-stranded-DNA restriction-digest fragments.


Biochemistry ◽  
1997 ◽  
Vol 36 (7) ◽  
pp. 1657-1668 ◽  
Author(s):  
Thomas Vogl ◽  
Claudia Jatzke ◽  
Hans-Jürgen Hinz ◽  
Jörg Benz ◽  
Robert Huber

2000 ◽  
Vol 48 (10) ◽  
pp. 4535-4539 ◽  
Author(s):  
Hiroya Ishikawa ◽  
Mitsuya Shimoda ◽  
Akiyoshi Yonekura ◽  
Keiko Mishima ◽  
Kiyoshi Matsumoto ◽  
...  

2021 ◽  
Vol 118 (12) ◽  
pp. e2026650118
Author(s):  
Katrine Z. Leth-Espensen ◽  
Kristian K. Kristensen ◽  
Anni Kumari ◽  
Anne-Marie L. Winther ◽  
Stephen G. Young ◽  
...  

The complex between lipoprotein lipase (LPL) and its endothelial receptor (GPIHBP1) is responsible for the lipolytic processing of triglyceride-rich lipoproteins (TRLs) along the capillary lumen, a physiologic process that releases lipid nutrients for vital organs such as heart and skeletal muscle. LPL activity is regulated in a tissue-specific manner by endogenous inhibitors (angiopoietin-like [ANGPTL] proteins 3, 4, and 8), but the molecular mechanisms are incompletely understood. ANGPTL4 catalyzes the inactivation of LPL monomers by triggering the irreversible unfolding of LPL’s α/β-hydrolase domain. Here, we show that this unfolding is initiated by the binding of ANGPTL4 to sequences near LPL’s catalytic site, including β2, β3–α3, and the lid. Using pulse-labeling hydrogen‒deuterium exchange mass spectrometry, we found that ANGPTL4 binding initiates conformational changes that are nucleated on β3–α3 and progress to β5 and β4–α4, ultimately leading to the irreversible unfolding of regions that form LPL’s catalytic pocket. LPL unfolding is context dependent and varies with the thermal stability of LPL’s α/β-hydrolase domain (Tm of 34.8 °C). GPIHBP1 binding dramatically increases LPL stability (Tm of 57.6 °C), while ANGPTL4 lowers the onset of LPL unfolding by ∼20 °C, both for LPL and LPL•GPIHBP1 complexes. These observations explain why the binding of GPIHBP1 to LPL retards the kinetics of ANGPTL4-mediated LPL inactivation at 37 °C but does not fully suppress inactivation. The allosteric mechanism by which ANGPTL4 catalyzes the irreversible unfolding and inactivation of LPL is an unprecedented pathway for regulating intravascular lipid metabolism.


Author(s):  
Maria S. Akimova

The study highlights relationship between changes in material culture (development of railroad network), social infrastructure (spread of dacha villages) and poetics of literary works in Russia of the second half of the 19th – early 20th c., addressing “dacha topos”. The paper draws on the texts, which introduce railroad as a symbol of destruction of traditional values under the pressure of bourgeois “industrialism” and pernicious “infernalityˮ (А. М. Zhemchuzhnikov, F. M. Dostoevsky, L. N. Tolstoy, A. S. Serafimovich, А. А. Blok and others). The author shows that dacha, wrought by railroad civilization, is conceptualized as part of packed, petty-bourgeois, low-minded and soulless city as opposed to country estate as a lone “paradise on earth” and hermitage of high culture (А. P. Tchekhov, N. А. Leykin, А. P. Kamensky and others). The paper draws attention to metamorphoses of artistic time in passing from “estate topos” with inherent temporal static and cycliсity to “dacha topos” with precipitous and irreversible unfolding in time. The author concludes that the changes in artistic topics and temporality when addressing successive phenomena of estate and dacha are largely due to such new details of subjective figurativeness as the railroad and its attributes (locomotive, rails, wagons, anonymous passengers, travel speed etc.).


1981 ◽  
Vol 59 (7) ◽  
pp. 551-555 ◽  
Author(s):  
Faizan Ahmad

The irreversible unfolding of acetylcholinesterase (acetylcholine hydrolyase, EC 3.1.1.7) by guanidine hydrochloride was studied by difference spectral, circular dichroic, and enzyme activity measurements. At pH 7.0 and in 1.1 M denaturant solution, a conformational state in which enzyme is completely inactive was detected. It is identical to the native enzyme as far as sedimentation coefficient and molecular weight are concerned, but differs from the native molecule by a slight loss in secondary structure and by a small perturbation of aromatic residues. Acetylcholinesterase in concentrated guanidine hydrochloride solution containing β-mercaptoethanol dissociates and exists as a random coil of molecular weight 68 000.


2020 ◽  
Vol 61 (9) ◽  
pp. 1253-1253 ◽  
Author(s):  
Kristian Kølby Kristensen ◽  
Katrine Zinck Leth-Espensen ◽  
Stephen G. Young ◽  
Michael Ploug

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