L Sugar

L (+) Arabmose is a naturally occurring L sugar It is obtained bj acid hydrolysis of the polysaccharide present in mesquite gum Write a Fischer pro ection for L (+) arabmose... 

The rules previously mentioned for assignment of a- and /3-configurations can be readily applied to Haworth projection formulas. For the D-sugars, the anomeric hydroxyl group is below the ring in the a-anomer and above the ring in the /3-anomer. For L-sugars, the opposite relationship holds. 

A mixture of methyl 3-deoxy-3-C-methyl-3-nitro-ct-D- and fi-L-glucopyranosides d l is formed by the reaction of nitroethane with the sugar thaldehyde obtained from L-glucose The products are separated and converted into branched-chain fluoro nitro l- and L-sugars fEq 361 ... 

The following cyclic structure is that of allose. Is this a furanose or pyranose form Is it an a or /3 anomer is it a D or L sugar ... 

Proteins are large biomolecules made up of a-amino acid residues linked together by amide, or peptide, bonds. Chains with fewer than 50 amino acids are often called peptides, while the term protein is reserved for larger chains. Twenty amino acids are commonly found in proteins all are a-amino acids, and all except glycine have stereochemistry similar to that of l sugars. In neutral solution, amino acids exist as dipolar zwitterions. 

L Sugar (Section 25.3) A sugar wTiose hydroxyl group at the chirality center farthest from the carbonyl group points to the left when drawm in Fischer projection. 

L. Sugar, J. Kozma, and F. Szego, Hung. Patent HU 21,693 to Ferrokemia Ipari Szovetkezet (1982). 

Anaerobic fermentation Water-l-sugar Carbon dioxide Yeast... 

D-Xylose, which is one of the most abundant sugars in plant polysaccharides, is a rare component of bacterial polysaccharides. It is found in the LPS of Type 1 Neisseria gonorrhoeae strain" GC 6. L-Xylose and its 3-methyI ether are components of the LPS of Pseudomonas maltophila strain NCTC 10257, and are j -pyranosidic. The d- and L-sugars, and different methyl ethers of these, have also been found in the LPS of some photosynthetic bacteria."... 

Fong, S., Machajewski, T.D., Mak, C.C. and Wong, C.-H. (2000) Directed evolution of D-2-keto-3-deoxy-6-phosphogluconate aldolase to new variants for the efficient synthesis of d- and L-sugars. Chemistry Biology, 7, 873-883. 

The role of L-glycerose as a precursor of l sugars is doubtful, since it inhibits glycolysis in plants and animals, probably by the formation of L-sorbose 1-phosphate, which inhibits hexokinase.74-75... 

Stractures of the various o-aldoses in the range C3-C6 are shown below. These compounds are multifunctional stmctures, having a carbonyl group and several hydroxyls, usually with two or more chiral centres. You will notice that we are comparing the stereochemistry in the different possible diastereoiso-mers for compounds containing several chiral centres (see Section 3.4.4). There is a corresponding series of enantiomeric L-sugars only a few of these are shown. 

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