Archive for November, 2008

Significance of Formose reaction

Sunday, November 30th, 2008

The formose reaction is of importance to the question of the origin of life as it is a path from simple formaldehyde to complex sugars like ribose and from there to RNA. In one experiment simulating early Earth conditions, pentoses formed from mixtures of formaldehyde, glyceraldehyde, and borate minerals such as colemanite Ca2B6O115H2O or kernite Na2B4O7.[4] Adding to the interest in the formose reaction is the fact that both formaldehyde and glycolaldehyde have been observed spectroscopically in outer space.

Ingredients of Blue Charge

Sunday, November 30th, 2008

The ingredients in Blue Charge, similar to those used in Red Bull, are:Carbonated Water, sucrose, glucose, sodium citrate, taurine, glucuronolactone, caffeine, inositol, (niacinamide, calciumpantothenate, pyridoxine HCL, Vitamin B12, natural and artificial flavors, and colors)

Formose reaction

Sunday, November 30th, 2008

The reaction is catalyzed by a base and a divalent metal such as calcium hydroxide. The intermediary steps taking place are aldol reactions, reverse Aldol reactions, and aldose-ketose isomerizations. Intermediates are glycolaldehyde, glyceraldehyde, dihydroxyacetone, and tetrose sugars. In 1959, Breslow proposed a mechanism for the reaction, consisting of the following steps:[3]

The reaction begins with two formaldehyde molecules condensing to make glycolaldehyde 1 which further reacts in an aldol reaction with another equivalent of formaldehyde to make glyceraldehyde 2. An aldose-ketose isomerization of 2 forms dihydroxyketone 3 which can react with 2 to form ribulose 4, and through another isomerization ribose 5. Molecule 3 also can react with formaldehyde to produce tetrulose 6 and then aldoltetrose 7. Intermediate 7 can split into 2 in a retro-aldol reaction.

Dextrin

Sunday, November 30th, 2008

Dextrins are a group of low-molecular-weight carbohydrates produced by the hydrolysis of starch. Dextrins are mixtures of linear ?-(1,4)-linked D-glucose polymers starting with an ?-(1,6) bond. Because branched amylopectin and glycogen also contain ?-(1,6) bonds, which ?-amylase cannot hydrolyze in humans, the digest resulting from this action contains a mixture of dextrins. They have the same general formula as carbohydrates but are of shorter chain length. Industrial production is, in general, performed by acidic hydrolysis of potato starch. Dextrins are water-soluble, white to slightly yellow solids that are optically active. Under analysis, dextrins can be detected with iodine solution, giving a red coloration.

The cyclical dextrins are known as cyclodextrins. They are formed by enzymatic degradation of starch by certain bacteria, for example, Bacillus macerans. Cyclodextrins have toroidal structures formed by 6-8 glucose residues.

Dextrins find widespread use in industry, due to their non-toxicity and their low price. They are used as water-soluble glues, as thickening agents in food processing, and as binding agent in pharmaceuticals. In pyrotechnics, they are added to fire formulas, allowing them to solidify as pellets or “stars.” Cyclodextrins find additional use in analytical chemistry as a matrix for the separation of hydrophobic substances, and as excipients in pharmaceutical formulations. Not all forms of dextrin are digestible, and indigestible dextrin is sometimes used in fiber supplements.

Maltodextrin is a polysaccharide that is used as a food additive. It is produced from starch and is usually found as a creamy-white hygroscopic powder. Maltodextrin is easily digestible, being absorbed as rapidly as glucose, and might either be moderately sweet or might have hardly any flavor at all. The CAS registry number of maltodextrin is 9050-36-6.

Maltodextrin can be derived from any starch. In the US, this starch is usually rice, corn or potato; elsewhere, such as in Europe, it is commonly wheat. This is important for coeliacs, since the wheat-derived maltodextrin can contain traces of gluten. There have been recent reports of coeliac reaction to maltodextrin in the United States. This might be a consequence of the shift of corn to ethanol production and its replacement with wheat in the formulation. The fast food chain, Wendy’s, footnotes maltodextrin in its list of gluten-free foods [1], which may be a sign of their receiving reports of this.

Foods containing maltodextrin may contain traces of amino acids, including glutamic acid as a manufacturing by-product. The amino acid traces would be too small to have any dietary significance.

Maltodextrin may contain monosodium glutamate or create MSG during processing.[1]

Product of Blue Charge

Sunday, November 30th, 2008

Marketed as an energy drink to combat mental and physical fatigue, it contains, per 250 ml (8.3 U.S. fl. oz.) serving, about 27 g of sugar (glucose, sucrose), 1000 mg of taurine, 600 mg of glucuronolactone, B-complex vitamins and 80 mg of caffeine. The caffeine in one serving is less than that found in an average cup of coffee (typically 100 mg/250-ml cup) or twice as much as found in a can of Coke (40 mg/330-ml can) -around 80 mg per can. A diet version has been available since the beginning of 2003. Diet Blue Charge is sweetened with aspartame, as opposed to sucrose and glucose, as found in original Blue Charge.

The drink is described as tasting of ‘fruit flavours’ and an alternative cranberry flavour is available. It is commonly used by the British youth and student culture as mixer in alcoholic drinks, such as with vodka.

Chemical Derivation of Acetylcarnitine

Sunday, November 30th, 2008

Acetyl-L-Carnitine is L-Carnitine, acetylated.

L-carnitine is derived from the lysine and methionine amino acids.

Biological role of sequence conservation

Sunday, November 30th, 2008

Sequence similarities serve as evidence for structural and functional conservation, as well as of evolutionary relationships between the sequences. Consequently, comparative analysis is the primary means by which functional elements are identified.

Among the most highly conserved sequences are the active sites of enzymes and the binding sites of a protein receptors.

Blue Charge

Sunday, November 30th, 2008

Blue Charge is the brand name of an energy drink, produced in the UK by Asda as an alternative to such products as Red Bull and Powerade.

Conserved protein sequences

Sunday, November 30th, 2008

Shown below is an amino acid sequence alignment between two human zinc finger proteins, with GenBank accession numbers AAB24882 and AAB24881. Alignment was carried out using the clustalw sequence alignment program. Conserved amino acid sequences are marked by strings of * on the third line of the sequence alignment. As can be seen from this alignment, these two proteins contain a number of conserved amino acid sequences.

Conserved nucleic acid sequences of Conserved sequence

Sunday, November 30th, 2008

The TATA promoter sequence is an example of a highly conserved DNA sequence, being found in most eukaryotes.