Dipeptide

C10H16N4O3. M.p. 238-239 "C. A dipeptide constituent of the muscles of various species. 

M.p. 246-250°C (decomp.). A dipeptide present in mammalian muscle. Like anserine it contains the amino-acid -alanine which is not found in proteins. 

NMR signals of the amino acid ligand that are induced by the ring current of the diamine ligand" ". From the temperature dependence of the stability constants of a number of ternary palladium complexes involving dipeptides and aromatic amines, the arene - arene interaction enthalpies and entropies have been determined" ". It turned out that the interaction is generally enthalpy-driven and counteracted by entropy. Yamauchi et al. hold a charge transfer interaction responsible for this effect. 

Crystal stmctures of complexes of copper(II) with aromatic amine ligands and -amino acids " " and dipeptides" have been published. The stmctures of mixed ligand-copper complexes of L-tryptophan in combination with 1,10-phenanthroline and 2,2 -bipyridine and L-tyrosine in combination with 2,2 -bipyridine are shown in Figure 3.2. Note the subtle difference between the orientation of the indole ring in the two 1,10-phenanthroline complexes. The distance between the two... 

A very mild and efficient synthesis of N-substituted -lactams uses the Mitsunobu reaction (see section 2.6.2) for the ring closure of seryl dipeptides protected at the terminal N as 4,5-diphenyloxazol-2(3f/)-one ( Ox ) derivatives (see section 2,6.3)... 

The synthesis described met some difficulties. D-Valyl-L-prolyl resin was found to undergo intramolecular aminoiysis during the coupling step with DCC. 70< o of the dipeptide was cleaved from the polymer, and the diketopiperazine of D-valyl-L-proline was excreted into solution. The reaction was catalyzed by small amounts of acetic acid and inhibited by a higher concentration (protonation of amine). This side-reaction can be suppressed by adding the DCC prior to the carboxyl component. In this way, the carboxyl component is "consumed immediately to form the DCC adduct and cannot catalyze the cyclization. 

J.E. Baldwin (1975, 1976A) has developed a biomimetic synthesis which is loosely analogous to the biosynthetic pathway which starts with the so-called Amstein tripeptide. Baldwin used bicyclic dipeptides more suitable for stereoselective in vitro syntheses. 

Aspartame is the market leader among artifi cial sweeteners It is a methyl ester of a dipeptide un related to any carbohydrate It was discovered in the course of research directed toward developing drugs to relieve indigestion... 

A dipeptide is a molecule consisting of two ammo acids joined by a peptide bond A tnpeptide has three ammo acids joined by two peptide bonds a tetrapeptide has four ammo acids and so on Peptides with more than 30-50 ammo acids are polypeptides Proteins are polypeptides that have some biological function... 

A key biochemical reaction of ammo acids is their conversion to peptides polypeptides and proteins In all these substances ammo acids are linked together by amide bonds The amide bond between the ammo group of one ammo acid and the carboxyl of another IS called a peptide bond Alanylglycme is a representative dipeptide... 

FIGURE 27 6 Structural features of the dipeptide l alanylglycine as determined by X ray crystallography... 

Expand your answer to Problem 27 10 by showing the struc tural formula for each dipeptide m a manner that reveals the stereochemistry at the a carbon atom... 

There are several levels of pepfide sfrucfure The primary structure is the ammo acid sequence plus any disulfide links With the 20 ammo acids of Table 27 1 as building blocks 20 dipeptides 20 tripeptides 20" tetrapeptides and so on are possible Given a peptide of unknown structure how do we determine its ammo acid sequence" ... 

Digestion of the tetrapeptide of Problem 27 13 with chy motrypsin gave a dipeptide that on ammo acid analysis gave phenylalanine and valine in equimolar amounts What ammo acid sequences are possible for the tetrapeptide ... 

Thus the synthesis of a dipeptide of prescribed sequence requires at least three operations... 

Higher peptides are prepared m an analogous way by a direct extension of the logic just outlined for the synthesis of dipeptides... 

An experiment using Boc protection in the synthesis of a dipeptide can be found in the November 1989 issue of the Journal of Chemical Education pp 965-967... 

Dipeptide (Section 27 7) A compound in which two a amino acids are linked by an amide bond between the amino group of one and the carboxyl group of the other... 

There are thousands of breweries worldwide. However, the number of companies using fermentation to produce therapeutic substances and/or fine chemicals number well over 150, and those that grow microorganisms for food and feed number nearly 100. Lists of representative fermentation products produced commercially and the corresponding companies are available (1). Numerous other companies practice fermentation in some small capacity because it is often the only route to synthesize biochemical intermediates, enzymes, and many fine chemicals used in minor quantities. The large volume of L-phenylalanine is mainly used in the manufacture of the artificial dipeptide sweetener known as aspartame [22389-47-0]. Prior to the early 1980s there was httle demand for L-phenyl alanine, most of which was obtained by extraction from human hair and other nonmicrobiological sources. 

There are numerous further appHcations for which maleic anhydride serves as a raw material. These appHcations prove the versatiHty of this molecule. The popular artificial sweetener aspartame [22839-47-0] is a dipeptide with one amino acid (l-aspartic acid [56-84-8]) which is produced from maleic anhydride as the starting material. Processes have been reported for production of poly(aspartic acid) [26063-13-8] (184—186) with appHcations for this biodegradable polymer aimed at detergent builders, water treatment, and poly(acryHc acid) [9003-01-4] replacement (184,187,188) (see Detergency). 

Endotoxin and Muramyl Dipeptide Derivatives. Bacterial cell wall constituents such as the Hpopolysaccharide endotoxin and muramyl dipeptide, which stimulate host defense systems, show radioprotective activity in animals (204). Although endotoxin is most effective when given - 24 h before irradiation, it provides some protection when adrninistered shortiy before and even after radiation exposure. Endotoxin s radioprotective activity is probably related to its Hpid component, and some of its properties may result from PG and leukotriene induction (204). 

Muramyl tripeptide phosphatidylethanolamine (MTP-PE), a synthetic analogue of muramyl dipeptide and an effective systemic macrophage activator, induces a variety of cytokines such as IL-1, IL-6, and TNE, as well as PGE2 (205). Preirradiation treatment of mice using MTP-PE encapsulated in Hposomes, which can intensify radioprotective abiHty, stimulates the monocyte/macrophage system and accelerates the recovery of hemopoietic cells. 

The principal pathway for the decomposition of aspartame begins with the cleavage of the ester bond, which may or may not be accompanied by cyclization (Eig. 2). The resultant diketopipera2ine and/or dipeptide can be further hydroly2ed into individual amino acids (qv). 

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