Asparagine isolation

Historically, L-aspartic acid was produced by hydrolysis of asparagine, isolated from protein hydrolysates, or by the resolution of chemically synthesized d,l-aspartate. With the discovery of aspartase (L-aspartatc ammonia lyase. Enzyme Commission [EC] 4.3.1.1) [5] fermentation routes to L-aspartic acid quickly superseded the initial chemical methods. After further characterization, enzymatic routes to the production aspartic acid from ammonium fumarate using aspartase 317... 

Characterization of One Neutral and Two Acidic Glyco-asparagines Isolated from the Urine of Patients with Aspartylglycosaminuria (AGU) , Journal of Biochemistry (Tokyo), 80, 195-201... 

Affinity chromatography on a lectin from Phaseolus vulgaris coupled to agarose has been used to purify human urinary erythropoietin. The structures (19)—(24) have been reported for glycosylated asparagines isolated from the urine of patients... 

From Pseudomonas mendocina five siderophores were isolated by chromatography. They are reported to have identical molecular masses of 1,152 Da (the also reported 3a) value of 929 Da is an error L. E. Hersman, private communication) and an identical amino acid composition, which has not been revealed 141a). Color reactions show the presence of a hydroxamate, but not of a catecholate grouping. A gene analysis suggests a partial sequence acyl-Asp-Dab-Ser-formylOHOm-Ser-formylOHOm where asparagine could be OHAsp and the C-terminal ornithine cOHOm 9b). In which way the five isomeric siderophores with identical molecular masses differ from each other is not clear. 

Asparagine, the amide of aspartic acid, was first isolated by Robi-quet and Vauquelin, in 1806, from the juice of Asparagus officinalis hence its name. Not only is asparagine found in asparagus, but also in the seedlings of lupines, peas, vetches, etc., from which it is best and most easily prepared. 

Yamashina and coworkers18 72 isolated, on Dowex 50, the total aspartamidoglycan from a proteolytic digest of ovalbumin. It had mean D-mannose hexosamine L-asparagine ratios of 5 3 1. Purified a-D-mannosidase liberated exactly half the D-mannose from the glycopeptide. The residue was subjected to chromatography on Bio-Gel... 

Collagen and basement membrane may contain several types of carbohydrate-peptide linkage. They clearly contain linkages in which 5-hydroxy-L-lysine is involved, as already discussed (see p. 436). From the preparations studied were also isolated glycopep-tides in which an asparagine-2-acetamido-2-deoxy-D-glucose linking moiety was present.1Bl-200... 

The corresponding a-anomer was isolated by this chromatography as a by-product iVJ-(Allyloxycarbonyl)-7/4-(2-acetamido-4-0-(2-acetamido-3,4-di-0-acetyl-6-0-benzyl-2-deoxy-(3-D-glucopyranosyl)-3-0-acctyl-6-0-(2,3,4-0-bcnzyl-a-L-fucopyranosyl)-2-deoxy-a-D-glucopyranosyl)-L-asparagine terf-butyl ester yield, 62 mg (10%) Rf 0.42 (CHC13-MeOH 10 1). 

The production of a-amino acids has a long history, starting with the isolation of asparagine from asparagus juice m 1806. The other er-amino acids were isolated from a variety of natural substances with threonine from fibrin being the last of these acids to be isolated and identified... 

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