The crude solid residue was recrystallized from methanol ether and gave 49 g. (56%) of product, m.p. 234-237'.Anal. Calcd. for CCH15C1S2O: C, 43.5; H, 9.0; C1, 21.3; N, 16.8. Found: C, 43.1; H, 9.0; C1, 21.0; S, 16.4. 0-Bromoamides .-The amides listed in Table I were made by reaction of acid chlorides with ammonia or amines either in aqueous or in anhydrous media. If a concentrated aqueous solution of the base was available commercially, the aqueous procedure was used. Ether or chloroform generally was used for the anhydrous bases. After filtration of the hydrochlorides of the bases the products were obtained by evaporation of the solvent and purifiea in the manner indicated in Table I. 2-Ethyl-2-( 2 -bromo-2-ethy1butyramido)-butyrarnide (LV) .-To a n ice-cold, stirred solution of 35 g. (0.21 mole) of 2-amino-2-ethylbutyramide hydrochloride in 300 cc. of Ivater and 50 cc. of acetone there was added, simultaneously, during 1 hour, a solution of 47.1 g. (0.22 mole) of 2-bromo-2-ethylbutyryl chloride in 100 cc. of acetone and 490 cc. (0.49 mole) of 1 N sodium hydroxide solution. The product separated as a white solid which was filtered and airdried. N-(2-Bromo-2-ethylbutyryl)-glycine (LII) .-To a solution of 2.8 g. (0.01 mole) of N-(2-bromo-2-ethylbutyryl)-glycine ethyl ester23 in 25 cc. of methanol, there was added, dropwise, a t 5", with stirring, 2 cc. (0.01 mole) of 5 N sodium hydroxide solution. After having been stored a t room temperature overnight the solution was concentrated under reduced pressure to remove most of the methanol and the (23) K. W. Rosenmund, Ber., 43, 4470 (1909).rryulting solutio11 was acidified with dilute l~ydrochloric acid to pH 1. The product separated from the coaled solution as a white precipitate which was filtered, n a 4 i e d with water, and dried.
1-(2-Bromo-2-ethylbutyryl)-3-methylurea (LVII I .-Amixture of 25 g. (0.34 mole) of N-methylurea and 36.1 g. (0.12 mole) of 2-bromo-2-ethylbutyryl chloride was heated on a steam-bath for six hours with occasional swirling. A clear reddish-brown solution formed to which 1% as added 100 g. of ice and 50 cc. of water. A gum formed nhich solidified upon trituration. The solid was filtered and washed first with cold water and then with petroleum ether (b.p. 20-40"). The crude solid was extracted with petroleum ether in a Saxhlet apparatus for 4 hours. Concentration of the solution t o a small volume gave the product as a white solid.
1-(2-Bromo-2-methylpropionyl)-3-methylurea (XXIII).-A mixture of 20 g. (0.12 mole) of 2-bromo-2-methylpropionyl chloride and 17.8 g. (0.24 mole) of methylurea was heated on a steam-bath for 0.5 hour. An oily solid formed and the mass was treated with water and -filtered. T h e white solid was dried on a porous plate.l-(2-Bromo-2-methylbutyryl)-3-methylurea (XXX).--A mixture of 37.1 g. (0.5 mole) of dried methylurea and 39.9 g. (0.2 mole) of 2-bromo-2-methylbutyryl chloride u as stirred and heated for 2 hours in a n oil-bath a t 60-87".To the mixture, consisting of a n amher liquid containing some colorless c...
The reactions of trypsin with its inhibitors are among the few known cases of specific interaction between two purified proteins (Kunitz & Northrop, 1936; Kunitz, 1947; Fraenkel-Conrat, Bean &
KNOX, K. W. (Twyford Laboratories, London, England), MARET VESK, AND ELIZABETH WORK. Relation between excreted lipopolysaccharide complexes and surface structures of a lysine-limited culture of Escherichia coli. J. Bacteriol. 92:1206-1217. 1966.-The lysine-requiring mutant Escherichia coli 12408, when grown in 15 liters of defined medium containing a suboptimal amount of lysine, showed a biphasic type of growth. During a long stationary phase of 15 hr, there was a steady accumulation of diaminopimelic acid (DAP) and an antigenic complex of lipopolysaccharide (LPS) and lipoprotein; the accumulation continued unchanged until the end of the second growth phase. The rapid rate of DAP excretion suggested that it was the result of a derepressed state of a biosynthetic pathway. LPS excretion was such that the amount in the culture fluid was doubled during a period corresponding to the normal generation time for the organism; this suggested that the LPS-lipoprotein complex was a product of unbalanced growth. Surface defects were suggested saccharide extracted from cells.
1. Some of the products excreted by cultures of lysine-requiring Escherichia coli A.T.C.C. 12408 grown under lysine-limiting conditions have been studied. 2. A glycolipid designated ;extracellular lipoglycopeptide' was prepared from culture filtrates of such organisms. It contained 35% of lipid, 19% of carbohydrate, 3.4% of P and 3.7% of N. 3. Comparison of the lipids, fatty acids, carbohydrates and amino acids of this lipoglycopeptide with those of whole cells, cell walls and cellular lipopolysaccharides shows that it has few features (except its residual lipids) in common with any of these fractions. 4. The lipoglycopeptide was antigenically related to both walls and lipopolysaccharide.
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