Role of oxidative mixed-disulfide formation in elastase–serine proteinase inhibitor (serpin) complex

1996 ◽  
Vol 74 (3) ◽  
pp. 391-401 ◽  
Author(s):  
Suresh C. Tyagi
Keyword(s):  
Conformational Changes ◽  
Proteinase Inhibitor ◽  
Acute Phase Proteins ◽  
Serine Proteinase ◽  
Disulfide Exchange ◽  
Disulfide Formation ◽  
Mixed Disulfide ◽  
Fluorescence Measurements ◽  
Disulfide Linkages

To understand the role of thiol and oxidative mixed-disulfide exchange reaction in serpins, we analyzed the conformation of native and mixed-disulfide forms of α1-proteinase inhibitor (α1PI), α1-antichymotrypsin (α1-ACT), α2-antiplasmin (α2-AP), angiotensinogen, and ovalbumin. The conformation of native and oxidized mixed-disulfide serpins was measured by transverse urea gradient (TUG) gels. The results suggest that the acute phase proteins α1-PI and α1-ACT undergo conformational changes following oxidative mixed-disulfide formation and that α2-AP and angiotensinogen do not. The kinetics of disulfide formation was followed by measuring changes in absorbance at 412 nm resulting from Ellman's reaction of disulfide exchange. The rate of mixed-disulfide formation in albumin was 10-fold faster than in the serpin tested. The rate of disulfide exchange in α1-PI was 2-fold faster than that of α1-ACT. However, disulfide formation in α1-PI and α1-ACT was much slower than for any other serpin, e.g., α2-AP and angiotensinogen. We present evidence that α1-PI forms a dimer sensitive to thiol reduction, suggesting cysteinyl-mediated dimerization of α1-PI. The α1-PI also demonstrated two types of inter-protein disulfide linkages: one resulting in homodimer and other involving heterodimer formation. TUG–Western immunoblot methodology was developed to identify the conformational changes in serpins. We found that the conformational changes in serpins by mixed-disulfide formation are due to unfolding and not to decomposition or degradation in TUG gels. Using fluorescence measurements with isolated tryptic fragments of fluorescence-labelled elastase, we observed that the cysteinyl232 in α1-PI interacted with the cysteinyl168 of elastase in the proteinase–inhibitor complex. Our data suggests that serpin thiols may play an important role in forming a stable serpin–proteinase complex.Key words: serpin, extracellular matrix, proteinase, reduction, oxidation, inhibitor.

Structural insights into the peroxidase activity and inactivation of human peroxiredoxin 4

2011 ◽  
Vol 441 (1) ◽  
pp. 113-118 ◽  
Author(s):  
Xi Wang ◽  
Likun Wang ◽  
Xi'e Wang ◽  
Fei Sun ◽  
Chih-chen Wang
Keyword(s):  
Endoplasmic Reticulum ◽  
Structural Analysis ◽  
Conformational Changes ◽  
Active Site ◽  
High Reactivity ◽  
Structural Explanation ◽  
Disulfide Formation ◽  
Redox Forms ◽  
Structural Insights

Prx4 (peroxiredoxin 4) is the only peroxiredoxin located in the ER (endoplasmic reticulum) and a proposed scavenger for H2O2. In the present study, we solved crystal structures of human Prx4 in three different redox forms and characterized the reaction features of Prx4 with H2O2. Prx4 exhibits a toroid-shaped decamer constructed of five catalytic dimers. Structural analysis revealed conformational changes around helix α2 and the C-terminal reigon with a YF (Tyr-Phe) motif from the partner subunit, which are required for interchain disulfide formation between Cys87 and Cys208, a critical step of the catalysis. The structural explanation for the restricting role of the YF motif on the active site dynamics is provided in detail. Prx4 has a high reactivity with H2O2, but is susceptible to overoxidation and consequent inactivation by H2O2. Either deletion of the YF motif or dissociation into dimers decreased the susceptibility of Prx4 to overoxidation by increasing the flexibility of Cys87.

Role of spectrin in membrane fusion and in shape change of human erythrocyte ghost

1978 ◽  
Vol 36 (2) ◽  
pp. 328-329
Author(s):  
Hideo Hayashi ◽  
Yoshikazu Hirai ◽  
John T. Penniston
Keyword(s):  
Conformational Changes ◽  
Human Erythrocyte ◽  
Shape Change ◽  
Membrane Surface ◽  
Slight Modification ◽  
Active Role ◽  
Main Role ◽  
Bank Blood ◽  
Human Erythrocyte Ghost

Spectrin is a membrane associated protein most of which properties have been tentatively elucidated. A main role of the protein has been assumed to give a supporting structure to inside of the membrane. As reported previously, however, the isolated spectrin molecule underwent self assemble to form such as fibrous, meshwork, dispersed or aggregated arrangements depending upon the buffer suspended and was suggested to play an active role in the membrane conformational changes. In this study, the role of spectrin and actin was examined in terms of the molecular arrangements on the erythrocyte membrane surface with correlation to the functional states of the ghosts.Human erythrocyte ghosts were prepared from either freshly drawn or stocked bank blood by the method of Dodge et al with a slight modification as described before. Anti-spectrin antibody was raised against rabbit by injection of purified spectrin and partially purified.

scholarly journals E3 Ubiquitin Ligase SPL2 Is a Lanthanide-Binding Protein

2021 ◽  
Vol 22 (11) ◽  
pp. 5712
Author(s):  
Michał Tracz ◽  
Ireneusz Górniak ◽  
Andrzej Szczepaniak ◽  
Wojciech Białek
Keyword(s):  
Ubiquitin Ligase ◽  
Conformational Changes ◽  
Protein Interactions ◽  
E3 Ubiquitin Ligase ◽  
Lanthanide Ions ◽  
E3 Ligases ◽  
Fluorescence Measurements ◽  
Partial Unfolding

The SPL2 protein is an E3 ubiquitin ligase of unknown function. It is one of only three types of E3 ligases found in the outer membrane of plant chloroplasts. In this study, we show that the cytosolic fragment of SPL2 binds lanthanide ions, as evidenced by fluorescence measurements and circular dichroism spectroscopy. We also report that SPL2 undergoes conformational changes upon binding of both Ca2+ and La3+, as evidenced by its partial unfolding. However, these structural rearrangements do not interfere with SPL2 enzymatic activity, as the protein retains its ability to auto-ubiquitinate in vitro. The possible applications of lanthanide-based probes to identify protein interactions in vivo are also discussed. Taken together, the results of this study reveal that the SPL2 protein contains a lanthanide-binding site, showing for the first time that at least some E3 ubiquitin ligases are also capable of binding lanthanide ions.

scholarly journals Role of conformational heterogeneity in ligand recognition by viral RNA molecules

2021 ◽  
Author(s):  
Lev Levintov ◽  
Harish Vashisth
Keyword(s):  
Conformational Changes ◽  
Ribonucleic Acid ◽  
Viral Rna ◽  
Ligand Recognition ◽  
Conformational Heterogeneity ◽  
Rna Molecules ◽  
Environmental Stimuli

Ribonucleic acid (RNA) molecules are known to undergo conformational changes in response to various environmental stimuli including temperature, pH, and ligands. In particular, viral RNA molecules are a key example...

Role of disulfide linkages in tachyplesin-lipid interactions

Biochemistry ◽  
1993 ◽  
Vol 32 (43) ◽  
pp. 11704-11710 ◽  
Author(s):  
Katsumi Matsuzaki ◽  
Mitsuya Nakayama ◽  
Masaru Fukui ◽  
Akira Otaka ◽  
Susumu Funakoshi ◽  
...  
Keyword(s):  
Lipid Interactions ◽  
Disulfide Linkages

scholarly journals The Serine Proteinase Inhibitor (Serpin) Plasminogen Activation Inhibitor Type 2 Protects against Viral Cytopathic Effects by Constitutive Interferon α/β Priming

1998 ◽  
Vol 187 (11) ◽  
pp. 1799-1811 ◽  
Author(s):  
Toni M. Antalis ◽  
May La Linn ◽  
Karen Donnan ◽  
Luis Mateo ◽  
Joy Gardner ◽  
...  
Keyword(s):  
Plasminogen Activator ◽  
Proteinase Inhibitor ◽  
Rapid Development ◽  
Serine Proteinase ◽  
Productive Infection ◽  
Interferon Α ◽  
Serine Proteinase Inhibitor ◽  
Cytopathic Effects ◽  
Inhibitor Type

The serine proteinase inhibitor (serpin) plasminogen activator inhibitor type 2 (PAI-2) is well characterized as an inhibitor of extracellular urokinase-type plasminogen activator. Here we show that intracellular, but not extracellular, PAI-2 protected cells from the rapid cytopathic effects of alphavirus infection. This protection did not appear to be related to an effect on apoptosis but was associated with a PAI-2–mediated induction of constitutive low-level interferon (IFN)-α/β production and IFN-stimulated gene factor 3 (ISGF3) activation, which primed the cells for rapid induction of antiviral genes. This primed phenotype was associated with a rapid development of resistance to infection by the PAI-2 transfected cells and the establishment of a persistent productive infection. PAI-2 was also induced in macrophages in response to viral RNA suggesting that PAI-2 is a virus response gene. These observations, together with the recently demonstrated PAI-2–mediated inhibition of tumor necrosis factor-α induced apoptosis, (a) illustrate that PAI-2 has an additional and distinct function as an intracellular regulator of signal transduction pathway(s) and (b) demonstrate a novel activity for a eukaryotic serpin.

Conformational Changes of Yeast Plasma Membrane H+-ATPase during Activation by Glucose:  Role of Threonine-912 in the Carboxy-Terminal Tail†

Biochemistry ◽  
2005 ◽  
Vol 44 (50) ◽  
pp. 16624-16632 ◽  
Author(s):  
Silvia Lecchi ◽  
Kenneth E. Allen ◽  
Juan Pablo Pardo ◽  
A. Brett Mason ◽  
Carolyn W. Slayman
Keyword(s):  
Plasma Membrane ◽  
Conformational Changes ◽  
Yeast Plasma Membrane ◽  
Carboxy Terminal
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