Methylglyoxal

About: Methylglyoxal is a research topic. Over the lifetime, 2844 publications have been published within this topic receiving 102037 citations. The topic is also known as: acetylformaldehyde & pyruvaldehyde.

Identification of glutathione (GSH)-independent glyoxalase III from Schizosaccharomyces pombe

Abstract: Reactive carbonyl species (RCS), such as methylglyoxal (MG) and glyoxal (GO), are synthesized as toxic metabolites in living systems. Mechanisms of RCS detoxification include the glutathione (GSH)-dependent system consisting of glyoxalase I (GLO1) and glyoxalase II (GLO2), and GSH-independent system involving glyoxalase III (GLO3). Hsp31 and DJ-1 proteins are weakly homologous to each other and belong to two different subfamilies of the DJ-1/Hsp31/PfpI superfamily. Recently, the Escherichia coli Hsp31 protein and the DJ-1 proteins from Arabidopsis thaliana and metazoans have been demonstrated to have GLO3 activity. We performed a systematic survey of homologs of DJ-1 and Hsp31 in fungi. We found that DJ-1 proteins have a very limited distribution in fungi, whereas Hsp31 proteins are widely distributed among different fungal groups. Phylogenetic analysis revealed that fungal and metazoan DJ-1 proteins and bacterial YajL proteins are most closely related and together form a sister clade to bacterial and fungal Hsp31 proteins. We showed that two Schizosaccharomyces pombe Hsp31 proteins (Hsp3101 and Hsp3102) and one Saccharomyces cerevisiae Hsp31 protein (ScHsp31) displayed significantly higher in vitro GLO3 activity than S. pombe DJ-1 (SpDJ-1). Overexpression of hsp3101, hsp3102 and ScHSP31 could confer MG and GO resistance on either wild-type S. pombe cells or GLO1 deletion of S. pombe. S. pombe DJ-1 and Hsp31 proteins exhibit different patterns of subcellular localization. Our results suggest that fungal Hsp31 proteins are the major GLO3 that may have some role in protecting cells from RCS toxicity in fungi. Our results also support the view that the GLO3 activity of Hsp31 proteins may have evolved independently from that of DJ-1 proteins.

Comparative Physiological and Biochemical Changes in Tomato (Solanum lycopersicum L.) Under Salt Stress and Recovery: Role of Antioxidant Defense and Glyoxalase Systems.

Abstract: Salinity toxicity and the post-stress restorative process were examined to identify the salt tolerance mechanism in tomato, with a focus on the antioxidant defense and glyoxalase systems. Hydroponically grown 15 day-old tomato plants (Solanum lycopersicum L. cv. Pusa Ruby) were treated with 150 and 250 mM NaCl for 4 days and subsequently grown in nutrient solution for a further 2 days to observe the post-stress responses. Under saline conditions, plants showed osmotic stress responses that included low leaf relative water content and high proline content. Salinity induced oxidative stress by the over-accumulation of reactive oxygen species (H2O2 and O2•-) and methylglyoxal. Salinity also impaired the non-enzymatic and enzymatic components of the antioxidant defense system. On the other hand, excessive Na+ uptake induced ionic stress which resulted in a lower content of other minerals (K+, Ca2+, and Mg2+), and a reduction in photosynthetic pigment synthesis and plant growth. After 2 days in the normal nutrient solution, the plants showed improvements in antioxidant and glyoxalase system activities, followed by improvements in plant growth, water balance, and chlorophyll synthesis. The antioxidant and glyoxalase systems worked in concert to scavenge toxic reactive oxygen species (ROS), thereby reducing lipid peroxidation and membrane damage. Taken together, these findings indicate that tomato plants can tolerate salinity and show rapid post-stress recovery by enhancement of their antioxidant defense and glyoxalase systems.

Formation of strand breaks and interstrand cross-links in DNA by methylglyoxal

Abstract: Methylglyoxal (MG), a dietary mutagen, is present in various frequently consumed beverages and foods and in cigarette smoke. A combination of S1 nuclease hydrolysis and alkaline unwinding assay was used to demonstrate the formation of single-strand breaks and interstrand cross-links in DNA upon treatment with MG. Calf thymus DNA, when treated with increasing concentrations of MG, showed an increasing degree of S1 nuclease hydrolysis. It also showed the formation of an increasing number of strand breaks per molecule as determined by an alkaline unwinding assay. Incubation of DNA with relatively higher concentrations of methylglyoxal or prolonged treatment gave increased thermal melting temperatures and an enhanced rate of reannealing after thermal denaturation. These results indicated the formation of interstrand cross-links. Upon treatment with MG, A-T base pair depleted DNA showed a reduced number of single-strand break formation. It also showed a significantly lower decrease in Tm as compared with MG-treated normal DNA. These results showed that under the conditions used, MG primarily reacts with A-T base pairs in duplex DNA.

Arginine-derived advanced glycation end products generated in peptide-glucose mixtures during boiling.

Abstract: Glycation refers to the reaction of amino groups, for example in proteins, with reducing sugars. Intermediately formed Amadori products can be degraded by oxidation (Maillard reactions) leading to a heterogeneous class of advanced glycation end-products (AGEs), especially during exposure to heat. AGEs are considered to be toxic in vivo due to their pronounced local and systemic inflammatory effects. At high temperatures, these reactions have been mostly investigated at the amino acid level. Here, we studied the formation of arginine-related AGEs in peptides under conditions simulating household cooking at physiological d-glucose concentrations. High quantities of AGE-modified peptides were produced within 15 min, especially glyoxal-derived products. The intermediately formed dihydroxy-imidazolidine yielded glyoxal- (Glarg) and methylglyoxal-derived hydro-imidazolinones (MG-H), with Glarg being further degraded to carboxymethyl-l-arginine (CMA). Carboxyethyl-l-arginine was not detected. The formation rates and yields were strongly increased in the presence of physiologically relevant concentrations of Fe(II)-ions and ascorbate. A nearby histidine residue increased the content of AGEs, whereas glutamic acid significantly reduced the CMA levels.