Erythrocyte glutathione transferase. A sensitive Up-Down biomarker of environmental and industrial pollution.

Erythrocyte glutathione transferase is a well-known biomarker of environmental pollution. Examination of the extensive scientific literature discovers an atypical and very interesting property of this enzyme which may reveal a chronic exposition to many contaminants but in some cases even an acute and short-term dangerous contamination. This review also underlines the peculiar molecular and kinetic properties of this enzyme which makes it unique in the panorama of enzymes used as biomarker for environmental contamination.

Animal Biomonitoring for the Surveillance of Environment Affected by the Presence of Slight Contamination by β-HCH.

The aim of this study was to evaluate the influence of hidden environmental pollution on some blood parameters of sheep to detect susceptible biomarkers able to reveal slight contamination. Four dairy sheep farms, two with semi-extensive and two with intensive type systems were involved in this study. Two farms in different systems were chosen as properly located in a southern area of Latium (Italy), close to the Sacco River, in which contamination with β-hexachlorocyclohexane (β-HCH) occurred in the past due to industrial waste.

Targeting Oncogenic Src Homology 2 Domain-Containing Phosphatase 2 (SHP2) by Inhibiting Its Protein-Protein Interactions.

We developed a new class of inhibitors of protein-protein interactions of the SHP2 phosphatase, which is pivotal in cell signaling and represents a central target in the therapy of cancer and rare diseases. Currently available SHP2 inhibitors target the catalytic site or an allosteric pocket but lack specificity or are ineffective for disease-associated SHP2 mutants. Considering that pathogenic lesions cause signaling hyperactivation due to increased levels of SHP2 association with cognate proteins, we developed peptide-based molecules with nanomolar affinity for the N-terminal Src homology domain of SHP2, good selectivity, stability to degradation, and an affinity for pathogenic variants of SHP2 that is 2-20 times higher than for the wild-type protein.

Oxidative Folding of Proteins: The "Smoking Gun" of Glutathione.

Glutathione has long been suspected to be the primary low molecular weight compound present in all cells promoting the oxidative protein folding, but twenty years ago it was found "not guilty". Now, new surprising evidence repeats its request to be the "smoking gun" which reopens the criminal trial revealing the crucial involvement of this tripeptide.

Trypsinogen and chymotrypsinogen: the mysterious hyper-reactivity of selected cysteines is still present after their divergent evolution.

An enigmatic and never described hyper-reactivity of most of the cysteines resident in the reduced, molten globule-like intermediate of a few proteins has been recently discovered. In particular, all ten cysteines of chymotrypsinogen showed hundred times increased reactivity against hydrophobic reagents. A single cysteine (Cys1) was also found thousand times more reactive toward GSSG, making speculate that a single glutathionylation could represent the primordial event of its oxidative folding.

New Factors Enhancing the Reactivity of Cysteines in Molten Globule-Like Structures.

Protein cysteines often play crucial functional and structural roles, so they are emerging targets to design covalent thiol ligands that are able to modulate enzyme or protein functions. Some of these residues, especially those involved in enzyme mechanisms-including nucleophilic and reductive catalysis and thiol-disulfide exchange-display unusual hyper-reactivity; such a property is expected to result from a low p and from a great accessibility to a given reagent. New findings and previous evidence clearly indicate that p perturbations can only produce two-four-times increased reactivity at physiological pH values, far from the hundred and even thousand-times kinetic enhancements observed for some protein cysteines.

A Pilot Study of a Natural Food Supplement as New Possible Therapeutic Approach in Chronic Kidney Disease Patients.

The identification of natural bioactive compounds, able to counteract the abnormal increase of oxidative stress and inflammatory status in chronic degenerative non-communicable diseases is useful for the clinical management of these conditions. We tested an oral food supplement (OFS), chemically characterized and evaluated for in vitro and in vivo activity. Vitamin C, analyzed by High Performance Liquid Chromatography-Diode Array Detector (HPLC-DAD), was 0.

Ultra-rapid glutathionylation of chymotrypsinogen in its molten globule-like conformation: A comparison to archaeal proteins.

Chymotrypsinogen, when reduced and taken to its molten globule-like conformation, displays a single cysteine with an unusual kinetic propensity toward oxidized glutathione (GSSG) and other organic thiol reagents. A single residue, identified by mass spectrometry like Cys1, reacts with GSSG about 1400 times faster than an unperturbed protein cysteine. A reversible protein-GSSG complex and a low pK (8.

Ultra-Rapid Glutathionylation of Ribonuclease: Is this the Real Incipit of its Oxidative Folding?

Many details of oxidative folding of proteins remain obscure, in particular, the role of oxidized glutathione (GSSG). This study reveals some unknown aspects. When a reduced ribonuclease A refolds in the presence of GSSG, most of its eight cysteines accomplish a very fast glutathionylation.

Hemodialysis biomarkers: total advanced glycation end products (AGEs) against oxidized human serum albumin (HSAox).

Aims: Nephropathic patients show higher levels of advanced glycation end products (AGEs) and oxidized human serum albumin (HSAox) compared to healthy subjects. These two classes of compounds are formed as the result of oxidative insults; for this reason, they can be useful oxidative stress biomarkers. The present study examines the variation of AGEs and HSAox in hemodialysis (HD) patients before and after dialysis session, evaluating the impact of different dialytic techniques and filters on their removal.

Glutathione Transferase P1-1 an Enzyme Useful in Biomedicine and as Biomarker in Clinical Practice and in Environmental Pollution.

Glutathione transferase P1-1 (GSTP1-1) is expressed in some human tissues and is abundant in mammalian erythrocytes (here termed e-GST). This enzyme is able to detoxify the cell from endogenous and exogenous toxic compounds by using glutathione (GSH) or by acting as a ligandin. This review collects studies that propose GSTP1-1 as a useful biomarker in different fields of application.

The impact of ionizing irradiation on liver detoxifying enzymes. A re-investigation.

By looking at many studies describing the impact of ionizing irradiations in living mice on a few key detoxifying enzymes like catalase, superoxide dismutase, glutathione peroxidase, glutathione reductase and glutathione transferase, we noted conflicting evidences: almost all papers finalized to demonstrate the protective effects of natural or synthetic drugs against the damage by irradiations, described also a relevant inactivation of these enzymes in the absence of these compounds. Conversely, no inactivation and even enhanced activity has been noted under similar irradiation modality in all studies supporting the "adaptive response". Motivated by these curious discrepancies, we performed irradiation experiments on living mice, explanted mouse livers and liver homogenates observing that, in all conditions the activity of all these enzymes remained almost unchanged except for a slight increase found in explanted livers.

The extreme hyper-reactivity of Cys94 in lysozyme avoids its amorphous aggregation.

Many proteins provided with disulfide bridges in the native state undergo amorphous irreversible aggregation when these bonds are not formed. Here we show that egg lysozyme displays a clever strategy to prevent this deleterious aggregation during the nascent phase when disulfides are still absent. In fact, when the reduced protein assembles into a molten globule state, its cysteines acquire strong hyper-reactivity towards natural disulfides.

Thiol disulfide exchange reactions in human serum albumin: the apparent paradox of the redox transitions of Cys.

Human serum albumin (HSA) is characterized by 17 disulfides and by only one unpaired cysteine (Cys ), which can be free in the reduced albumin or linked as a mixed disulfide with cysteine, or in minor amount with other natural thiols, in the oxidized albumin. In healthy subjects, the level of the oxidized form is about 35%, but it rises up to 70% after oxidative insults or in patients with kidney diseases. Oxidized albumin is therefore considered a short-term biomarker of oxidative stress as its level may increase or decrease under appropriate redox inputs in discrete temporal spans.

Erythrocyte glutathione transferase in kidney transplantation: a probe for kidney detoxification efficiency.

Erythrocyte glutathione transferase (e-GST) is overexpressed in case of increased blood toxicity and its level correlates with the kidney disease progression. Thus, it represents a probe of kidney efficiency against circulating toxins. We measured the activity of e-GST in patients with transplant kidney from living and cadaver donors, correlated its level to biochemical parameters of kidney function, and measured the level of oxidized albumin as a probe of oxidative stress using a new simple procedure.

Structure of a PEGylated protein reveals a highly porous double-helical assembly.

PEGylated proteins are a mainstay of the biopharmaceutical industry. Although the use of poly(ethylene glycol) (PEG) to increase particle size, stability and solubility is well-established, questions remain as to the structure of PEG-protein conjugates. Here we report the structural characterization of a model β-sheet protein (plastocyanin, 11.