Rapid assessment of human amylin aggregation and its inhibition by copper(II) ions by laser ablation electrospray ionization mass spectrometry with ion mobility separation.

Native electrospray ionization (ESI) mass spectrometry (MS) is often used to monitor noncovalent complex formation between peptides and ligands. The relatively low throughput of this technique, however, is not compatible with extensive screening. Laser ablation electrospray ionization (LAESI) MS combined with ion mobility separation (IMS) can analyze complex formation and provide conformation information within a matter of seconds.

Glutamine Synthetase Sensitivity to Oxidative Modification during Nutrient Starvation in Prochlorococcus marinus PCC 9511.

Glutamine synthetase plays a key role in nitrogen metabolism, thus the fine regulation of this enzyme in Prochlorococcus, which is especially important in the oligotrophic oceans where this marine cyanobacterium thrives. In this work, we studied the metal-catalyzed oxidation of glutamine synthetase in cultures of Prochlorococcus marinus strain PCC 9511 subjected to nutrient limitation. Nitrogen deprivation caused glutamine synthetase to be more sensitive to metal-catalyzed oxidation (a 36% increase compared to control, non starved samples).

Copper(II)-human amylin complex protects pancreatic cells from amylin toxicity.

Human amylin-derived oligomers and aggregates are believed to play an important role in the pathogenesis of type II diabetes mellitus (T2DM). In addition to amylin-evoked cell attrition, T2DM is often accompanied by elevated serum copper levels. Although previous studies have shown that human amylin, in the course of its aggregation, produces hydrogen peroxide (H2O2) in solution, and that this process is exacerbated in the presence of copper(ii) ions (Cu(2+)), very little is known about the mechanism of interaction between Cu(2+) and amylin in pancreatic β-cells, including its pathological significance.

Hydrogen peroxide induced oxidation of peroxisomal malate synthase and catalase.

Peroxisomes contain oxidases that produce H(2)O(2), which can result in protein oxidation. To test the vulnerability of peroxisomal proteins to oxidation in vivo the organelles were isolated from castor bean endosperm incubated with H(2)O(2). When peroxisomes were exposed to H(2)O(2)in vivo, the peroxisomal proteins exhibited an increase in carbonylation as detected in avidin blots of biotin hydrazide derivatized samples.

A protective association between catalase and isocitrate lyase in peroxisomes.

Glyoxysomes are specialized peroxisomes in germinating seeds, which catalyze many reactions that convert fatty acids into carbohydrates thus generating H(2)O(2). They are characterized by the presence of catalase (CAT, E.C.

Ascorbate peroxidase, a scavenger of hydrogen peroxide in glyoxysomal membranes.

Efficient destruction of hydrogen peroxide (H(2)O(2)) in peroxisomes requires the action of an anti-oxidant defense system, which consists of low molecular weight anti-oxidant compounds, such as ascorbic acid, along with protective enzymes, such as catalase and ascorbate peroxidase (APX). We investigated the contribution of the ascorbate enzyme system to the consumptions of H(2)O(2) and NADH within glyoxysomes of germinating castor beans (Ricinus communis). We solubilized the glyoxysomal membrane APX (gmAPX) using octyl-glucoside and purified its activity by gel filtration.