Alanine synthesis and

Kumagai and coworkers11131 developed an enzymatic procedure to produce d-alanine from fumarate by means of aspartase (E. C. 4.3.1.1), aspartate racemase, and D-amino acid aminotransferase (Fig. 17-12). Aspartase catalyzes conversion of fumarate into L-aspartate, which is racemized to form D-aspartate. D-Amino acid aminotransferase catalyzes transamination between D-aspartate and pyruvate to produce D-alanine and oxalacetate. This 2-oxo acid is easily decarboxylated spontaneously to form pyruvate in the presence of metals. Thus, the transamination proceeds exclusively toward the direction of D-alanine synthesis, and total conversion of fumarate into D-alanine was achieved. 

FIG. 5.4 Alanine synthesis and the reoxidation of glycolytic NADH. 1, Glycolysis 2, alanine aminotransferase 3, NAD-dependent glutamate dehydrogenase 4, NADP-dependent glutamate dehydrogenase 5, malate dehydrogenase 6, malic enzyme (cytosolic). 

Cardinaux F, Howard JC, Taylor GT, Scheraga HA (1977) Block copolymers of amino-acids. 1. Synthesis and stmcture of copolymers of L-alanine or L-phenylalanine with D, L-lysine-D7 or D, L-lysine. Biopolymers 16 2005-2028... 

Fmoc-y9-alanine was pre-activated by introducing the pentafluorophenyi function as an ester group [88]. Dmab-y0-alanine and the pentafluorophenyi ester of Fmoc-/ -alanine reacted and the synthesis of the corresponding y0-dipeptide was realized. 

Keefe et al. (1995) from Stanley Miller s laboratory reported a possible prebiotic synthesis of pantetheine, the part of the CoA molecule without its ADP moiety. They were able to synthesize the CoA precursor from P-alanine, pantoyllactone and cysteamine. This condensation requires concentration of the reaction mixture the warm lagoon theory is required here in order to achieve prebiotic conditions ... 

K. Sato, N. Hada, and T. Takeda, Synthesis of new peptidic glycoclusters derived from /1-alanine Di- and trimerized glycoclusters and glycocluster-clusters, Carbohydr. Res., 341 (2006) 836-845. 

Synthesis and storage pathways are on degradative pathways are off. AA = amino acids KB = ketone bodies ALA = alanine LAC = lactate. 

Gluconeogenesis is the de novo synthesis of glucose from none carbohydrate sources. These sources (precursors) are lactic acid, glycerol and the amino acids, especially alanine, glntamine and aspartic acid (Fignre 6.22). 

Alanine synthesis in muscle The synthesis and release of alanine by muscle can be considered as a safety mecha-... 

Enantiopure (5)-fluoroalanine has been prepared by an enzymatic path starting from 3-fluoropyruvate in the presence of alanine dehydrogenase, and also by chemical synthesis from (5)-p-tolyl methyl sulfoxide (Figure 5.1) or from the L-serine. The analogue labeled with F has been prepared for use in positron emission tomography (PET) used in cancer diagnosis. ... 

Sensitivity to light presents a problem when the 4-azidophenylalanine moiety is introduced in early stages of the synthesis and is then carried through further synthetic procedures. Ideally, the azido function is introduced as late as possible into the synthesis. N4-Protected 4-aminophenyl-alanine can be introduced as a non-photoreactive precursor for the 4-azido form. The different pKs values of the a-amino and 4-amino groups (9.1 and 4.25, respectively) allow selective acylation of the 4-amino group at pH 4.0J29 The following procedures describe the synthesis of N4-, N°- and C-protected derivatives of 4-aminophenylalanine, as well as its activated esters. 

An enantioselective synthesis of ferrocenyl-modified alanines 91 and 93 was also reported.163 In this case, an organozinc derivative of serine 90 was coupled to iodoferrocene 89 or 1,1 -diiodoferrocene 92 using a palladium catalyst [Pd2(dba)3] to give the Boc-ferrocenyl-L-ala-nine methyl esters 91 and 93 in 60 and 64% yield, respectively (Scheme 26). 

With the aim of preparing photoinduced electron transfer devices or simply to be used as fluorescent reporter groups, the synthesis and utility of pyrene-L-alanine have been reported on several occasions. Regarding the development of charge-transfer devices, it was shown that intramolecular electron transfer occurred in 310- and a-helical peptidic systems, such as 182 and 185, between a pyrene and a dimethylaminophenyl chromophore (Scheme 51).[95 101] The rates depend on the relative orientation of the chromophoric side chains and on the framework conformation. Therefore, the preparation of tailor-made charge-transfer devices with tunable properties can be envisaged. 

Table 20 presents the results pertaining to the synthesis and properties of the gels. The gels are seen to sorb heparin from plasma solution. Their capacity (the maximal amount of heparin sorbed) increases as the mobility and accessibility of the cholesterol fragment for the macromolecules of heparin is increased by varying the length of the polymethylene spacer. The data in Table 20 illustrate that the capacity varies from 0.7 to 0.9 and 1.3 mg/mg of immobilized UChD for cholesterol esters of N-meth-acryloyl-fS-alanine (n — 2), N-acryloyl-co-aminoenantic acid (n = 6), and N-meth-acryloyl-co-aminolauric acid (n = 11), respectively. 

---