Hexamic acid

Synonyms cyclamate cyclohexanesulfamic acid N-cyclo-hexylsulfamic acid E952 hexamic acid Sucaryl. 

Synonyms Cyclamate Cyclohexanesulfamic acid Cyclohexylamidosulfuric acid Cyclohexylaminesulfonic acid Cyclohexylsulfamic acid Hexamic acid Sucaryl Sucaryl acid Empiricai C6H13NO3S... 

N,N,N, N, N",N"-Hexamethyl-1,3,5-triazine-2,4,6-triamine. See Hexamethylmelamine 1,1,1,3,3,3-Hexamethyl-2-trimethylsilyltrisilane. See Tris (trimethylsilyl) silane 2,2,4,4,6,6-Hexamethyl-[1,3,5,2,4,6] trioxatrisilinane. See Hexamethylcyclotrisiloxane Hexamethyl violet. See Basic violet 3 Hexamic acid. See Cyclamic acid Hexamidine CAS 3811-75-4... 

The conversion of the cyclic hexamer of fiiran and acetone into naphthafiirophane was reported <96TL6201>. Stepwise synthesis of core-modified, zncso-substituted porphyrins (e.g., 19) was achieved by acid catalyzed condensations <96TL197>. 

The metal and acid labile sulfur contents of these proteins was somewhat lower than expected by comparison with the MoFe proteins. AcP contained 2 0.3 vanadium atoms, 21 1 iron atoms, and 19 0.2 acid-labile sulfur atoms per a2)32 hexamer (172). The a2fi2(S) form of Avl was reported to contain 1.4 0.2 vanadium atoms, 21.4 iron atoms, and 24 acid-labile sulfur ions per molecule, and the afi2 form had lower levels of metal and sulfur (173). 

Probably the best example of the manifestation of self-assembly processes in dendritic systems via H-bonds is seen in the recent work of Zimmerman et al. [156]. Dendritic wedges possessing tetraacid moieties (67) self-assembling into a hexameric, disc-like framework (68) was confirmed by SEC and -NMR studies. The tetraacid unit (69) is known to form cyclic as well as linear aggregates in solution via carboxylic acid dimerization (Fig. 30). However, with incorporation of larger dendritic wedges on 69, the hexamer form is preferred. 

Studies have indicated that the association of HF in the gas phase leads predominantly to dimers or hexamers with small amounts of tetramers. Hydrogen bonding in liquids such as sulfuric and phosphoric acids is responsible for them being viscous liquids that have high boiling points. 

Proinsulin is proteolytically processed in the coated secretory granules, yielding mature insulin and a 34-amino acid connecting peptide (C peptide, Figure 11.1). The C peptide is further proteolytically modified by removal of a dipeptide from each of its ends. The secretory granules thus contain low levels of proinsulin, C peptide and proteases, in addition to insulin itself. The insulin is stored in the form of a characteristic zinc-insulin hexamer, consisting of six molecules of insulin stabilized by two zinc atoms. 

The genes that respond to a specific hormone contain identical HRE (Fig. 1.6). Normally, it is a matter of short nucleotide sequences pentamers or hexamers. In the case of the ER, the sequences are found repeated in inverse order in the same strand of DNA (palindromic, or symmetrically legible sequences 5 GGACA-nnn-ACAGG 3 n is any nucleotide). In the case of the thyroid hormones and retinoic acid, the HRE at times are presented like two repeated sequences in the same order (direct repetition GGACA-GGACA). 

The cyclic hexamer 9 (named rosette ) presents 18 hydrogen bonds48,49 9 is the first step in the formation of the cyanuric acid/melamine lattice formed by a sheet of non-covalent aggregates50. 

The major components are series of homologous trimers, tetramers, and pentamers of the three acids 44-46, along with smaller quantities of dimers, hexamers, and heptamers. Furthermore, the secretion contains several isomers of each oligomer, furnishing a combinatorial library of several hundred macro-cyclic polyamines [51, 52]. Using repeated preparative HPLC fractionation, the most abundant trimeric, tetrameric and pentameric earliest-eluting compounds were isolated. One and two-dimensional H NMR spectroscopic analyses showed that these molecules were the symmetric macrocyclic lactones 48, 49, and 50 (m, n, o, p, q=7) derived from three, four or five units, respectively, of acid 46. Moreover, using preparative HPLC and NMR methods, various amide isomers, such as 53,54, and 55 (Fig. 9) were also isolated and characterized [51,52]. 

The histone octamer is the histone unit of the nucleosome. As discussed in Section II, it has been shown that at high salt concentration (7 > 2 M) the core histones can assemble on their own, in the absence of DNA, to form histone octamers (this assembly occurs with both acid- and salt-extracted histones). Furthermore, the secondary and tertiary structures of core histones at high salt concentration are similar to the structures they have in the intact nucleosome. The basic units of the assembly of the four core histones are histone dimers which are obtained at low salt concentration. Upon increase in salt concentration, tetramers, hexamers, and octamers are obtained. The cross-linking pattern of histones in high salt concentration is similar to that in chromatin, again supporting the idea that the assembly of core histones at high salt concentration is similar to that in chromatin. 

ESl-MS of cysteine solutions yields only the singly protonated hexamer [(Cys)6-H]. No preference for the chirality of the individual aminoacidic components is observed." Addition of cysteine to a serine solution yields abundant homochiral mixed octamer [(L-Ser)g m(L-Cys) -H] (m = 0-2). No [(L-Ser)g. (D-Cys)m H]+ (m = 1,2) octamers, but only [(L-Ser)g-H]+ are observed by using the wrong D-cysteine enantiomer. A similar picture is observed by replacing cysteine with other aminoacid, such as aspartic acid, asparagine, leucine, and methionine. 

Despite their lack of stabilizing disulfide bridges Potl inhibitors feature a common, stable fold. The N-terminus is coiled, although in some structures a small /3-strand has been identified. After a turn the structure adopts an a-helical structure, followed by a turn and an other /3-strand. The sequence then features an extended turn or loop motif that contains the reactive site of the inhibitor before it proceeds with a /3-strand running almost parallel to the /3-strand after the a-helix. After another turn and coiled motif a short /3-strand antiparallel to the other /3-strands precedes the coiled C-terminus. Usually the N-terminal residue in the reactive site is an acidic residue followed by an aromatic amino acid, that is, tyrosine or phenylalanine. Figure 11 shows the complex of chymotrypsin inhibitor (Cl) 2 with subtilisin, the hexamer of Cl 2 from H. vulgare and a structural comparison with a trypsin inhibitor from Linum usitatissimum ... 

Carothers decided to concentrate on the development of polyamides, as silk is also a polyamide (Houshell and Smith 1988). The best polymer should have a high enough melting point to be washed and ironed, but not too high to allow the polymer to be drawn and spun before it would decompose. The raw materials adipic acid and hexame-thylenediamine could be produced from benzene, which was plentiful, so it was the 6,6 -polyamide (nylon-66) that first went into production in 1939. Carothers committed... 

Varela et al. have described some stereoregular hydroxylated polymannaramides (91) [93] by reaction of o-mannaro-l,4 6,3-dilactone (90) with even-numbered alkylenediamines (n = 2, 6, 8, 10, 12). Hydroxylated stereoregular and nonstereoregular polyamides were also prepared by the same authors [94] from hexam-ethylene diamine and pentachlorophenyl (25)-5-oxo-2-tetrahydrofurancarboxylate 93, the latter being derived [95] from the chiral (25)-2-hydroxypentanedioic acid 5,2-lactone (92), a compound obtained [96] by deamination of the easily available L-glutamic acid. 

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