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Aug 2 11 2:49 PM

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Antimicrobial Peptides From Plants

By an eHow Contributor

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Antimicrobial peptides in seeds

Antimicrobial peptides are molecular proteins that fight bacteria, viruses and fungi. These peptides, which are referred to as AMPs, are positively charged molecules that are active in plant seeds. The peptides attack cells and kill them helping to rid plant organisms of harmful bacteria. According to the journal "Critical Reviews in Plant Sciences," these antimicrobial peptides are found in almost all plant species.

Peptide discoveries in plants have not been frequent until recently. According to "Oxford Journals" Nucleic Acids Research, in 1942 the first antimicrobial peptide in a plant was discovered by Balls and Hale. They discovered the peptide in a wheat plant. It wasn't until three decades later that another such discovery was made. In 2008 a program called PhytAMP was created to catalog and record information on antimicrobial peptides to allow easier access to the information.

Antimicrobial peptides are cells in the seed of a plant. The peptides help to protect the plant from diseases that could harm it. The antimicrobial peptide cells target bacterial or viral cells and destroy them by breaking them down at the membrane level and eliminating the threat to the plant. Their discovery has lead to breakthrough research and advancement for the medical and agricultural fields.

The journal "Critical Reviews in Plant Sciences" states that antimicrobial peptides are effective by targeting microorganisms at their plasma membranes. The journal also states that there may be peptides that attack by different methods, but these have not yet been discovered. The peptides in the seed of the plant line the outer cell layer of the organ where they can take a defensive stance. The peptides are placed ideally to defend the plant from outside contamination.

Plants produce antimicrobial peptides as a defense against disease-producing viruses or bacterium. According to "Oxford Journals" Nucleic Acids Research, genetic engineering of these AMPs could help to increase antibiotic resistance in plants, which could impact agriculture as well as pharmaceutical industries. Researchers are finding the peptides could mean new developments for future antibiotics.
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According to Emilio Montesinos of the Institute of Food and Agricultural Technology at the University of Girona in Spain, antimicrobial peptides are being used to replace pesticides that have been banned in the agricultural industry. Scientists are trying to develop new forms of protection and prevention that are less harmful to the environment and still help farmers grow productive crops.

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#1 [url]

Aug 28 12 8:15 AM

Hey guys

Peptides with antimicrobial properties are present in most if not all plant species. All plant antimicrobial peptides isolated so far contain even numbers of Cysteines (4, 6, or 8), which are all pairwise connected by Disulfide bridges, thus providing high stability to the peptides. Based on homologies at the primary structure level, plant antimicrobial peptides can be classified into distinct families including Thionins, plant Defen sins, lipid transfer proteins, and he vein- and Knottin-type antimicrobial peptides.

Thanks a lot
Daquan Gibson

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#2 [url]

Aug 28 12 3:27 PM

Disulfide bridges are not a measure of antimicrobial action. I study an antioxidant protein in red blood cells for my PhD, with three cysteines, which is needed to detox hydrogen peroxide. 
Malaria parasites can kidnap the human one to protect themselves. 

Antimicrobial action is a highly variable. All enzymes and proteins are made of peptides. peptides are short chains of amino acids. 

Antimicrobial peptides have different ways of action: one: lysis of the cell membrane, like some saponins, inhibition of growth like lactoferrin by stealing nutrients, marking pathogens for the immune system and modulating the immune system like some defensins and production of free radicals inside and outside the cells (or stealing radicals needed for growth signals) like vitamin c  and inhibition of the pathogens' own antioxidant defences, like auranofin or most sulfur compounds (sulforaphine). 

But yes, ALL plants have some antimicrobial defence, since they cannot run away from threats and need to defend themselves. The biggest questions are: does it survive the stomach acid, does it need activation from the liver, will it work inside our bodies, will it be taken up at all? 

Best aggressive compounds are found so far in everything that is spicy or sharp, like peppers, cabbages (broccoli), watercress, leeks, onions and garlic. 
But in the long run, its great if you kill off every bacteria and parasite in your gut, but you need good bacteria and a healthy microbial flora, too. Without it, the gut is still leaky. 

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