Asparagine discovery

Historically, L-aspartic acid was produced by hydrolysis of asparagine, by isolation from protein hydrolysates, or by the resolution of chemically synthesized d,L-aspartate. With the discovery of aspartase (L-aspartate ammonia lyase, EC 4.3.1.1),57 fermentation routes to L-aspartic acid quickly superseded the initial chemical methods. These processes are far more cost effective than the fermentation routes, and aspartate is now made exclusively by enzymatic methods that use variations of the general approach outlined in Scheme 2.19.53-57-65... 

The discovery that dolichol phosphates and pyrophosphates (diphosphates) are carriers for oligosaccharides in eukaryotic cells initiated the modem era of glycoprotein biochemistry. These lipid-linked oligosaccharides are precursors for the carbohydrate side chains of the asparagine-linked glycoproteins. Because of this common precursor, all of the side chains of these glycoproteins share the same carbohydrate core, shown within the dashed box in Figure 16-la. 

Murphy s law certainly prevails in peptide synthesis. Some important side reactions, such as the formation of urethanes in coupling via alkylcarbonic acid mixed anhydrides or the generation of A-acylureas and dehydration of asparagine side chains when DCC is used for peptide bond formation, have already been mentioned in this chapter. Yet, countless additional side reactions and by-products have been observed and reported, often only as a footnote. Thus, it would be difficult to give a historical account of their discovery. A review [50] of side reactions noted in peptide synthesis reveals that most of them are caused by strong acids and bases, by excessive protonation or deprotonation of the amino add and peptide derivatives brought into reaction. 

Recently, after the discovery of the chemical mechaiusm governing this food-related contaminant, acrylamide production has been described through a series of reactions known as Maillard reaction, between an amino acid, primarily asparagines, and a reducing sugar such as fructose or glucose [21-25] (Figure 13.1). The amino acid... 

The isolation of protein from natural sources began as early as 1747 when Beccari reported on the isolation of gluten from wheat flour. However, the discovery of specific AAs started in 1806 with the isolation of asparagine from asparagus shoots. By 1935, with the isolation of threonine, all of the AAs commonly found in natural proteins had been isolated. The industrial production of isolated AAs began in 1909 when L-glutamic acid was first extracted from a hydrolysate of... 

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