Showing posts with label honey. Show all posts
Showing posts with label honey. Show all posts
Sunday, March 15, 2015
Honey Hydrophobicity and Biofilms
A reader (Jay Bryant) recently pointed out a PNAS article on the structure of a bacterial enzyme that uses sucrose to make the glucan matrix of dental biofilms. This article released a cascade of associations in my mind and illustrated why honey does not contribute to dental plaques, but is antimicrobial and aids wound healing. People forget that sugars combine both hydrophilic and hydrophobic properties, and thereby act as soaps.
The starting point of the chemical versatility of carbohydrates is the inability of the central portion of a sugar ring structure to form hydrogen bonds. Each sugar is made of a linear chain of carbon atoms with each carbon linked also to a hydrogen and a hydroxyl. Only the hydroxyl can participate in hydrogen bonds, so each carbon has a hydrophilic side (bonds with water to make hydrogen bonds) and a hydrophobic side (that makes van der Waals bonds with other hydrophobic molecules.) The sugars circularize and the rings have faces that are predominantly hydrophobic and perimeters with hydroxyls that are hydrophilic. Polysaccharides (long chains of sugars), such as cellulose, can sometimes form long fibers that form a hydrophobic context for hydrogen bonds between the hydroxyls of adjacent polymers. These cellulose fibers are very resistant to chemical or biological attack and accumulate as the most abundant biological molecules on Earth.
The PNAS article provides another example of how protein enzymes interact with carbohydrates, in this case sucrose and a polymer of glucose. Typical weak bonds between the amino acid residues of proteins and other molecules are hydrogen, ionic or van der Waals bonds with energies of a couple of kcals/mol. In contrast, the bonding of the hydrophobic face of a sugar to the hydrophobic face of an hydrophobic amino acid, e.g. tryptophan, phenylalanine, histidine, lysine or arginine, releases more than ten kcals/mol of energy. Thus, the structure of the bacterial enzyme that makes biofilm glucan chains from dietary sucrose, the sucrose is bound to the enzyme on the face of a prominent tryptophan. Examination of enzymes that bind to polysaccharides will show a series of tryptophans arrayed across the surface of the enzymes with spacing appropriate to bind to the individual sugars of the polysaccharide.
Biofilms are communities of multiple species of bacteria held together by a polysaccharide matrix. In the case of dental plaque, the polysaccharide is made of glucose links, whereas many other matrix polysaccharides are negatively charged and held together by positively charged metal ions. The bacteria bind to the polysaccharides using protein receptors that exploit the display of hydrophobic binding sites of the polysaccharides. It takes energy to make polysaccharides and the dental plaque bacteria use the energy already expended in the formation of sucrose to produce a polymer of glucose, an alpha-glucan, and free fructose. Thus, sucrose is essential in forming this type of biofilm and without this sugar, the dental plaque cannot form. Milk lactose, or glucose would be a more appropriate sweetener. Unfortunately, high fructose corn syrup would be a poor substitute, because of the high liver toxicity of the fructose (it causes fatty liver, just like alcohol) and very high activity in forming advanced glycation end products (AGEs), which contribute to the symptoms of diabetics.
Honey seems to be magical, because at low concentrations the sugars present in honey (mostly glucose and fructose, and not sucrose) are nutrients for bacteria, but at high concentrations honey is anti-bacterial and useful as a wound treatment. I think that the explanation for its antimicrobial activity is that sugars are amphipathic, that is they have both hydrophilic and hydrophobic properties, just like soap, and at high concentrations they kill bacteria, just as soaps at high concentrations kill bacteria. In fact, the gentle soaplike properties of sugars are exploited experimentally to dissolve proteins that are normally embedded in cellular membranes. This explanation predicts that corn syrup, which can also be used to form very stable soap bubbles, should also be useful in wound healing.
Friday, March 6, 2015
Baked Honey Mustard Coho Salmon Easy to Prepare and Full of DHA EPA B12 Selenium and More
Salmon Provides Vital Nutrients to your Diet
Cohos are in season and I’ve seen some pretty amazing deals lately. I usually buy a few pounds, slice the fillets in thin, 4 to 6 oz pieces and freeze some for later. Although summer is the ideal time for eating mostly raw fruits and vegetables, fish meals provide very important nutrients. In particular, EPA and DHA omega 3 fatty acids, vitamin B12, niacin, vitamin B6, selenium and phosphorus. Salmon is low in mercury so it can be enjoyed regularly.
EPA and DHA are the omega 3 fatty acids most beneficial to your health and are vital for brain development and maintaining healthy arteries. You cannot get EPA and DHA from plants. The body can convert ALA omega 3 into EPA and DHA but not everyone’s body does this efficiently. One half of the fat in the human brain is DHA. This nutrient is especially important for pregnant women for proper fetal development.
You also cannot get vitamin B12 from plants. So vegans MUST supplement with this vitamin or they may eventually suffer from megaloblastic anemia, nerve demyelinization and other nervous system problems like confusion and depression. This is a good reason for raw foodists to enjoy an occasional piece of salmon.
Six ounces of Coho salmon cooked with dry heat provides:
236 calories
8 g fat
2 g saturated fat
94 mg cholesterol
0 carbohydrates
0 fiber
40 grams protein
1.9 g omega 3
1.8 g EPA and DHA
0.1 g omega 6
13.6 mg niacin (68% DV)*
1 mg B6 (48% DV)
8.6 mcg B12 (142% DV)
64.6 mcg selenium (92% DV)
548 mg phosphorous (54% DV)
* for adults based on a 2,000 calorie reference diet. Source, Nutritiondata.com
Fast and Easy
With 5 minutes of preparation and less than 15 minutes cooking time, this may be one of the easiest recipes you will ever make. I served this to a dozen people last weekend so feel free to double, triple and quadruple the recipe. The only difference is, it may take an extra minute or so to cook when you have lots of salmon in the pan.
***
Baked Honey Mustard Coho Salmon [serves 2]
3/4 pound wild Coho Salmon filet
1 teaspoon extra virgin olive oil
1 1/2 teaspoons Dijon mustard
2 teaspoons local honey
1/2 teaspoon freshly squeezed lemon juice
1/4 teaspoon salt
Freshly ground black pepper to taste
1 teaspoon fresh parsley, chopped -optional
Preheat oven to 400 degrees. Lightly grease a small baking dish with olive oil. Wash off the salmon and pat dry with a paper towel. Cut into 2 equal pieces. Rub the pieces briefly in the oiled pan skin side up to coat the salmon and then turn them skin side down. In a small cup, mix mustard, honey, lemon juice and sea salt until smooth. Spoon the mixture over the top and sides of the salmon. Bake for 12 minutes or until salmon flakes with a fork (do not over cook). Top with black pepper to taste and garnish with chopped parsley. Serve immediately.
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