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From Wikipedia, the free encyclopedia

Methylglyoxal
Names
IUPAC name
2-Oxopropanal
Other names
Pyruvaldehyde
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard 100.001.059
KEGG
MeSH Methylglyoxal
UNII
Properties
C3H4O2
Molar mass 72.06 g·mol−1
Appearance Yellow liquid
Density 1.046 g/cm3
Boiling point 72 °C (162 °F; 345 K)
Related compounds
Related compounds
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is ☑Y☒N ?)
Infobox references

Methylglyoxal, also called pyruvaldehyde or 2-oxopropanal, is the organic compound with the formula CH3C(O)CHO. Gaseous methylglyoxal has two carbonyl groups, an aldehyde and a ketone but in the presence of water, it exists as hydrates and oligomers.[1] It is a reduced derivative of pyruvic acid.

YouTube Encyclopedic

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  • Honey: Bacteria's Worst Enemy
  • What are Manuka Honey Benefits and Side Effects?
  • UMF 20+ vs KFactor 22 vs MGO 550 (Top Manuka Honey Compare)
  • Benefits of Manuka Honey
  • Glutathione | Toxins, Detox, Antioxidant, Free Radical Scavenger, Amino Acids Uptake, Cell Membranes

Transcription

Honey. You’ve met honey. It’s that sticky, sweet stuff. Basically just slightly liquidy sugar in a plastic bear bottle, right? Wrong! Honey is a supercharged bacteria-killing powerhouse. And it’s all down to what those hardworking bees put into it, from immune proteins to the sugar itself. Since ancient times, honey has been used to prevent wounds from getting infected. And these days, we use purified and standardized versions of honey to fight infections in hospitals. Honey has three main tricks for fighting bacteria. The first is all that sugar. Honey is only about 17% water. Most--but not all--of what remains is sugar. The two main types of sugar in honey are glucose and fructose. Like all sugars, glucose and fructose are sticky -- they attract water. Honey is technically a supersaturated solution, meaning it contains more sugar than would normally dissolve at that temperature. That’s why it eventually gets all crystally in the pantry -- over time, the sugar comes out of the solution. Chemically speaking, it’s desperate for water. Water can travel across cell membranes from where there’s a higher concentration of water to where there’s a lower concentration. And there’s a higher concentration of water in a bacterium than in honey. Which means that honey will suck the juices right out of any bacterium -- or mold, or fungus -- that tries to set up shop. Plus, there’s isn’t enough water in honey for any microorganisms to live on. So they die, and the honey doesn’t spoil. The second thing, is that when bees make honey, they throw in an enzyme called glucose oxidase. And bacteria hate glucose oxidase because it produces two different compounds. It converts glucose to gluconic acid and hydrogen peroxide. Gluconic acid is, you guessed it, an acid. It gives honey a pH value of less than 4. That’s about a thousand times more acidic than the neutral pH of 7 that most bacteria need to grow. And hydrogen peroxide is very good at killing cells. It destroys the cell walls of bacteria, which breaks them apart. Glucose oxidase isn’t active in ripe honey--there’s not enough water for it to work properly. It seems to be there to keep the honey from spoiling while the bees are drying it out. But if you dilute honey, the glucose oxidase will switch back on and make gluconic acid again. The final thing bees do to make honey antibacterial? They put antibiotics in it. Some types of honey contain a protein called bee defensin-1, which is exactly what it sounds like. Bee defensin-1 defends bees. It’s part of their immune system and protects them from certain bacteria, including ones that could cause nasty diseases inside the hive. It’s produced in a gland that bees use to make honey, so it makes sense that some of it would make it into the finished product. And while scientists aren’t sure how much of the protein is really in honey, it sort of makes sense that bees would use it to protect their food. Another antibacterial compound sometimes found in honey is methylglyoxal. Methylglyoxal is a small organic molecule that forms in honey from a compound in the nectar of certain flowers. There’s an especially large amount of methylglyoxal in manuka honey, a honey made from a New Zealand flower. This honey is so good at killing bacteria that it’s actually used in hospitals. There’s one bacterium that has honey’s number--but only sort of. It’s the type of bacteria that that causes botulism. The bacteria start out as spores, which are very hard to kill. They’re already dried out, so honey’s water-sucking properties don’t kill them, and because the spores aren’t growing, they aren’t affected by the acidity or the antibiotic compounds. The really dangerous part of the bacteria is the botulinum toxin they produce when they grow into mature bacteria. Less than a hundred nanograms -- that’s billionths of a gram -- is enough to kill an adult. About 10% of honeys have some botulinum spores in them. But since the spores in honey aren’t growing and making toxin, they’re harmless to healthy adults. Our immune systems intercept the spores before they can start growing inside of us. But the immune systems of infants aren’t always able to kill those spores before they start growing. So, in rare cases, the bacteria can germinate and start producing toxin. That’s why it’s not safe to give honey to infants under one year old, but the rest of us don’t need to worry about it. So the next time you’re looking for something sweet, go ahead -- eat some of bacteria’s worst enemy. Thanks for watching this episode of SciShow, which was brought to you by our patrons on Patreon. Thank you, so much, to all of those people. If you want to be one of those people you can go to patreon.com/scishow. And if you just want to keep getting smarter with us, don’t forget to go to youtube.com/scishow and subscribe!

Contents

Industrial production and biosynthesis

Methylglyoxal is produced industrially by degradation of carbohydrates using overexpressed methylglyoxal synthase.[2]

In organisms, methylglyoxal is formed as a side-product of several metabolic pathways.[3] It may form from 3-aminoacetone, which is an intermediate of threonine catabolism, as well as through lipid peroxidation. However, the most important source is glycolysis. Here, methylglyoxal arises from nonenzymatic phosphate elimination from glyceraldehyde phosphate and dihydroxyacetone phosphate, two intermediates of glycolysis.

Aristolochic acid caused 12-fold increase of methylglyoxal from 18 to 231 μg/mg of kidney protein in poisoned mice.[4]

Biochemistry

Since methylglyoxal is highly cytotoxic, several detoxification mechanisms have evolved. One of these is the glyoxalase system. Methylglyoxal is detoxified by glutathione. Glutathione react with methylglyoxal to give a hemithioacetal, which converted into S-D-lactoyl-glutathione by glyoxalase I.[5] This thioester is hydrolyzedto D-lactate by glyoxalase II.[6]

The proximate and ultimate causes for biological methylglyoxal production remain unknown, but it may be involved in the formation of advanced glycation endproducts (AGEs).[7] In this process, methylglyoxal reacts with free amino groups of lysine and arginine and with thiol groups of cysteine forming AGEs. The heat shock protein 27 (Hsp27) is a specific target of posttranslational modification by methylglyoxal in human metastatic melanoma cells.[8]

Methylglyoxal binds directly to the nerve endings and by that increases the chronic extremity soreness in diabetic neuropathy.[9][10]

Other glycation agents include the reducing sugars:

Natural occurrence

Due to increased blood glucose levels, methylglyoxal has higher concentrations in diabetics and has been linked to arterial atherogenesis. Damage by methylglyoxal to low-density lipoprotein through glycation causes a fourfold increase of atherogenesis in diabetics.[11]

Although methylglyoxal has been shown to increase carboxymethyllysine levels,[12] methylglyoxal has been suggested to be a better marker for investigating the association between AGEs with adverse health outcomes.

Methylglyoxal is a component of some kinds of honey, including manuka honey; it appears to have activity against E. coli and S. aureus and may help prevent formation of biofilms formed by P. aeruginosa .[13]

References

  1. ^ Loeffler Kirsten W.; Koehler Charles A.; Paul Nichole M.; De Haan David O. (2006). "Oligomer Formation in Evaporating Aqueous Glyoxal and Methyl Glyoxal Solutions". Environmental Science & Technology. 40: 6318–6323. doi:10.1021/es060810w.
  2. ^ Frieder W. Lichtenthaler "Carbohydrates as Organic Raw Materials" in Ullmann's Encyclopedia of Industrial Chemistry 2010, Wiley-VCH, Weinheim. doi: 10.1002/14356007.n05_n07
  3. ^ Inoue Y, Kimura A (1995). "Methylglyoxal and regulation of its metabolism in microorganisms". Adv. Microb. Physiol. Advances in Microbial Physiology. 37: 177–227. doi:10.1016/S0065-2911(08)60146-0. ISBN 978-0-12-027737-7. PMID 8540421.
  4. ^ Li, Biochem Biophys Res Commun 423:832 2012 PMID 22713464 doi: 10.1016/j.bbrc.2012.06.049
  5. ^ Thornalley PJ (2003). "Glyoxalase I—structure, function and a critical role in the enzymatic defence against glycation". Biochem. Soc. Trans. 31 (Pt 6): 1343–8. doi:10.1042/BST0311343. PMID 14641060.
  6. ^ Vander Jagt DL (1993). "Glyoxalase II: molecular characteristics, kinetics and mechanism". Biochem. Soc. Trans. 21 (2): 522–7. PMID 8359524.
  7. ^ Shinohara M; Thornalley, PJ; Giardino, I; Beisswenger, P; Thorpe, SR; Onorato, J; Brownlee, M (1998). "Overexpression of glyoxalase-I in bovine endothelial cells inhibits intracellular advanced glycation endproduct formation and prevents hyperglycemia-induced increases in macromolecular endocytosis". J Clin Invest. 101 (5): 1142–7. doi:10.1172/JCI119885. PMC 508666. PMID 9486985.
  8. ^ Bair WB 3rd, Cabello CM, Uchida K, Bause AS, Wondrak GT (April 2010). "GLO1 overexpression in human malignant melanoma". Melanoma Res. 20 (2): 85–96. doi:10.1097/CMR.0b013e3283364903. PMC 2891514. PMID 20093988.
  9. ^ Spektrum: Diabetische Neuropathie: Methylglyoxal verstärkt den Schmerz: DAZ.online. Deutsche-apotheker-zeitung.de (2012-05-21). Retrieved on 2012-06-11.
  10. ^ Bierhaus, Angelika; Fleming, Thomas; Stoyanov, Stoyan; Leffler, Andreas; Babes, Alexandru; Neacsu, Cristian; Sauer, Susanne K; Eberhardt, Mirjam; et al. (2012). "Methylglyoxal modification of Nav1.8 facilitates nociceptive neuron firing and causes hyperalgesia in diabetic neuropathy". Nature Medicine. 18 (6): 926–33. doi:10.1038/nm.2750. PMID 22581285.
  11. ^ Rabbani N; Godfrey, L; Xue, M; Shaheen, F; Geoffrion, M; Milne, R; Thornalley, PJ (May 26, 2011). "Glycation of LDL by methylglyoxal increases arterial atherogenicity. A possible contributor to increased risk of cardiovascular disease in diabetes". Diabetes. 60 (7): 1973–80. doi:10.2337/db11-0085. PMC 3121424. PMID 21617182.
  12. ^ Cai, W., Uribarri, J., Zhu, L., Chen, X., Swamy, S., Zhao, Z., Grosjean, F., Simonaro, C., Kuchel, G. A., Schnaider-Beeri, M., Woodward, M., Striker, G. E., and Vlassara, H. (2014) Oral glycotoxins are a modifiable cause of dementia and the metabolic syndrome in mice and humans. PNAS 111.
  13. ^ Israili, ZH (2014). "Antimicrobial properties of honey". American Journal of Therapeutics. 21 (4): 304–23. doi:10.1097/MJT.0b013e318293b09b. PMID 23782759.
This page was last edited on 27 October 2018, at 00:56
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