Acetyl-L-leucine

A recent report describes the conversion of A-formyl- and N-acetyl-L-leucine into optically active azlactones with dicyclohexyl-carbodiimide (DCC) [Eq. (29)]. Other cyclization reagents, e.g. acetic anhydride, POCI3, SOCI2, and polyphosphoric acid, cause racemiza-tion. These azlactones react with optically active amino acid esters to give esters of dipeptides with retention of activity. 

C20H25NO4 73074-37-2) see Atracurium besilate (/t)-tetrabydropapaverine 7V-acetyl-L-leucinate (C2gH4(,N207 141109-12-8) see Cisatracurium besylate ( )-tetrabydropapaverine bydrocbloride (C20H26CINO4 6429-04-5) see Cisatracurium besylate [ -( , 5 )]-2,3,4,9-tetrabydro-7V-(l-phenylethyt)-lff-carbazol-3-amine sulfate (1 1)... 

Figure 8. Methyl-orientation results for the three methyl groups in N-acetyl-L-leucine. A, x-ray determined p(r) charge density map. B, graph showing relation between the H-C-C-H methyl torsion angles determined from the x-ray results and those determined by using a quantum chemical geometry optimization. The rms error is 8°.

CpaTi(L)2 [L JV-acetyl-L-leucine, AT-acetyl-L-methionine, (-) camphonate, O-acetyl-R-mandelate)... 

C8H13N 3-ethyl-2,4-dimethyl-1 H-pyrrole 517-22-6 20.00 0.9130 1 14830 C8H15N03 N-acetyl-L-leucine 1188-21-2 25.00 1.0543 2... 

Several later model systems were designed with the thought of separating products that are not enantiomers but diastereoisomers of each other. For instance in the coupling of acetyl-L-leucine to glycine ethyl ester racemization will yield acetyl-D-alloisoleucyl-glycine ethyl ester, because inversion at the a-carbon atom leads to a D-amino acid but chirality at the second chiral center, the -carbon atom is unaffected... 

L-N-Acetylhistidine monohydrate, 38B, 493, N-(Bromoacetyl)-L-leucine, 41B, 536 Acetyl-L-proline-N-methylamide, 37B, 272 Cyclobis(N-methyl-L-alanyl), 42B, 358 Cyclosarcosyl-L-valyl, 41B, 537 rac-Cyclobis(N-methylalanyl), 42B, 358 H2O, L-Prolylsarcosine monohydrate, 46B, J-Acetyl-L-leucine, 41B, 539... 

A -Acetyl-6A -methyl-L-leucine amide [32483-15-1] M 186.3. Recrystd from EtOH/hexane mixture. 

G, glycine H, histidine I, isoleucine L, leucine K, lysine M, methionine F, phenylalanine P, proline S, serine T, threonine O, tyrosine V, valine. Basic residues are in-dictated by squares and acidic residues are indicated by circles. Ac denotes acetylation site. 

Acetyl-l-methyl-l-cyclohexene [6090-09-1] M 138.2, 73-75 /7.5mm, 85-86 /13mm, 94-94.7 /20mm, 204.5-206 /747mm, d 1.0238, n p 1.469. Purified by fractionation under reduced pressure in vacuo, and when almost pure it can be fractionated at atmospheric pressure, preferably in an inert atm. Forms two semicarbazones one of which is more soluble in C H, and both can be recryst from EtOH, more soluble has m 149 (151 ), and the less soluble has m 172-175°(191°). 4-Nitrophenylhydrazone has m 166-167° and the 2,4-dinitrophenylhydrazone has m 114-115 . [/7CA 17 129, 140 1934 A 564 109 7949]. 7V-Acetyl-67V -methylglycinamide [7606-79-3] M 130.2. Recrystd from EtOH/Et2O mixture. 7V-Acetyl-67V -methyl-L-leucine amide [32483-15-1 ] M 186.3. Recrystd from EtOH/hexane mixture. 

Figure 9 HPLC chromatograms of culture broth of S. fradiae MBBF-c (A) and S. fradiae MBBF-c(pABllAEH) (B, C). In the fermentation at (C), L-leucine was fed into the culture, and the supernatant was diluted by 20-fold with acetonitrile for analysis. Abbreviations I, tylosin VI, 3-O-acetyltylosin VII, 3,4"-di-0-acetyltylosin VIII, 3-(9-acetyl-4"-O-propionyl tylosin IX, 3-0-accty 1 -4 O- b ut y ry I ty I o si n X, 3-0-acetyl-4"-0-isovalerylty-losin (AIV). (From Ref. 22.)...

Figure 10 Time course of fermentation with S. fradiae harboring pABllAEH using a 3-liter jar fermenter. Titers of AIV (3-0-acetyl-4"-0-isovaleryltylosin) and other related compounds during 10-day fermentation are presented. Residual L-leucine (Leu) determined is also indicated from the 6th day to the last day of fermentation. Abbreviations for acyltylosins 3-AT, 3-O-acetyltylosin 3,4"-AAT, total amount of 3-0-acetyl-4"-0-acyltylosins except AIV 3-AR, 3-O-acetylrelomycin (3-O-acetyl-20-dihydrotylosin) 3-HAIV, 3-0-acetyl-4"-0-(3-hydroxyisovaleryl)tylosin.

The binding constant of the substrate acetyl-L-leucyl-L-tyrosine methylamide to pepsin (Km) is reported as 2.7 mM and the binding of the inhibitor acetyl-D-tyrosyl-D-leucine methylamide (Kt) as 5.8 mM. The binding shown in Fig. 6 was proposed for the reason that both binding constants are almost identical. This assumption is based upon the idea that the space-filling structure of leucyltyrosine in the L-configuration is similar to that of the reversed sequence, tyrosylleucine, in the D-configuration. A... 

Several structures of proteasome inhibitor complexes have been determined by X-ray crystal analysis [22, 50, 51]. Calpain inhibitor I (acetyl-L-L-norleudnal) was covalently bound to Thr-1 of the /91, pi and y95 subunits, respectively. This peptide aldehyde inhibitor is attacked by the threonyl Oy to form a hemiacetal. The nor-leucine side chain projects into a pocket with an opening in its side towards a tunnel leading to the particle surface. The leucine side chain at P2 is not in contact with the protein, whilst the leucine side chain at P3 is in contact with the adjacent / -type subunit. 

Magnesium or lithium enolates of thiol carboxylic esters can be acylated with suitable reagents (c/ Volume 2, Part 1). Highly functionalized new derivatives are obtained. The example shown in equation (35)33,102 J5 closely related to the C-acylation of malonyl-CoA with acetyl-CoA, which plays an important role in the biosynthesis of polypeptides and fatty acids. (S)-4-Hydroxy-5-methyl-3-oxo-hexanoyl-L-leucine esters (41), 2-demethyl analogs of the Hip-Leu moiety of didemnin antibiotics, can be prepared via the 3-keto thiol carboxylic esters (40 equation 36). ° ... 

Die Prafixe werden in alien Derivaten vor den Nainen der Aminosaure gesetzt (z. B. Acetyl-L-tryptophan, 4-Oxy-L-prolin, Glycyl-DL-leucin, jedoch nicht Phenyl-L-alanin, sondern nach wie vor L-Phenylalanin). 

A-Acetyl-A -methyl-L-leucine amide [32483-15-1] M 186.3, m 165.3-166.8 (sealed tube), [a] n -33.9 (c 1, H2O). Recrystallise the amide from EtOAc, EtOH/hexane mixture or toluene/hexane mixture. [Applewhite Niemann J Am Chem Soc 81 2212 7959.]... 

Fig. 19. Michaelis-Menten constant f Al-acetyl-L-amino add methyl esters with a-chymotrypsin versus the effluent volume of the amino acid from a cation-exchange resin [72]. 1, glydne 2, alanine 3, aminoisobutyric acid 4, valine S, methionine 6, leucine 7, tyrosine 8, phenylalanine.

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