Solid-phase synthesis of a modified 13-residue seminalplasmin fragment on 1,6-hexanediol diacrylate-crosslinked polystyrene support

A novel 1,6-hexanediol diacrylate cross-linked resin was prepared that was subsequently functionalized by using chloromethyl methyl ether to afford a high-capacity resin. The resin exhibited good swelling and its application in the successful synthesis of a 13-residue peptide corresponding to the fragment of seminalplasmin has been illustrated. The resin was chemically inert at peptide synthetic conditions.     

Solid phase synthesis of hydrophobic peptides on 1,6-hexanediol diacrylate cross-linked polystyrene resin.

The synthesis of three hydrophobic peptides, which are partial sequences of thioredoxin, on a newly developed, flexible 1,6-hexanediol diacrylate cross-linked polystyrene, in good yield and purity, is described.     

Suppression of liquid–liquid phase separation by 1,6-hexanediol partially compromises the 3D genome organization in living cells

Liquid–liquid phase separation (LLPS) contributes to the spatial and functional segregation of molecular processes within the cell nucleus. However, the role played by LLPS in chromatin folding in living cells remains unclear. Here, using stochastic optical reconstruction microscopy (STORM) and Hi-C techniques, we studied the effects of 1,6-hexanediol (1,6-HD)-mediated LLPS disruption/modulation on higher-order chromatin organization in living cells. We found that 1,6-HD treatment caused the enlargement of nucleosome clutches and their more uniform distribution in the nuclear space. At a megabase-scale, chromatin underwent moderate but irreversible perturbations that resulted in the partial mixing of A and B compartments. The removal of 1,6-HD from the culture medium did not allow chromatin to acquire initial configurations, and resulted in more compact repressed chromatin than in untreated cells. 1,6-HD treatment also weakened enhancer-promoter interactions and TAD insulation but did not considerably affect CTCF-dependent loops. Our results suggest that 1,6-HD-sensitive LLPS plays a limited role in chromatin spatial organization by constraining its folding patterns and facilitating compartmentalization at different levels.     

Dissimilation of methionine by fungi

Soil fungi that attacked methionine required a utilizable source of energy such as glucose for growth. This is an example of co-dissimilation. Experiments with one of the fungi, representative of the group, are reported. In the absence of glucose, pregrown mycelium, even when depleted of energy reserves, oxidatively deaminated methionine with accumulation of α-keto-γ-methyl mercapto butyric acid and α-hydroxy-γ-methyl mercapto butyric acid. When glucose was provided, all of the sulfur of methionine was released as methanethiol, part of which was oxidized to dimethyl disulfide. No sulfate, sulfide, or hydrosulfide products were detected. Evidence was obtained that deaminase and demethiolase were constitutive. Deamination preceded demethiolation and α-keto butyric acid accumulated as a product of the two reactions. Other carbon residues were α-hydroxy butyric acid and α-amino butyric acid. Inability of the fungus to metabolize α-keto butyrate was responsible for its inability to utilize methionine as a source of carbon and energy. Several other fungi isolated from soil grew on α-amino butyrate but could not grow on methionine owing to inability to demethiolate it.     

Dissimilation of methionine by a demethiolase of Aspergillus species

Enzyme preparations obtained from the mycelium of Aspergillus species broke down methionine by co-dissimilation. The deaminase and demethiolase activities of crude extracts were increased 100-fold by precipitation with (NH(4))(2)SO(4) and column chromatography on diethylaminoethyl cellulose. The enzyme acted on d-methionine but not on l-methionine. The enzyme was labile: it was inactivated by oxygen and ascorbic acid but ethylenediaminetetraacetic acid and mercaptoethanol preserved its activity. Enzyme activity decreased even at 4 and -30 C and was lost rapidly above 45 C. It was most rapid at 35 C and at pH 8.0 to 9.0. For the following reasons, it was concluded that deamination and demethiolation of methionine were effected by the same enzyme: both activities increased equally at each stage of purification; ammonia, methanethiol, and alpha-keto butyric acid were formed in amounts equivalent to the amount of methionine dissimilated; the K(m) and optimal pH for formation of both keto acid and methanethiol were the same; both activities remained in the same fractions that were separated by electrophoresis and the activities were equivalent. The purified enzyme demethiolated alpha-keto methionine and alpha-hydroxy methionine and split the sulfur linkage of ethionine but did not cleave cystathionine. Few amino acids were deaminated. The enzyme was sensitive to some carbonyl and sulfhydryl reagents and was relatively insensitive to heavy metals other than Hg(++). The K(m) was 1.3 x 10(-3) to 1.5 x 10(-3)m at pH 7.0. No requirement for cofactors was noted, and attempts to dissociate the enzyme, including dialysis with hydroxylamine, were unsuccessful.     

Nitrate Dissimilation Under Microaerophilic Conditions by a Magnetic Spirillum

During microaerophilic growth of magnetic spirillum MS-1 on tartrate and nitrate, a maximal cell density was obtained at an initial oxygen partial pressure of 17 Pa. A transient accumulation of nitrous oxide and a 1:2 (mol/mol) stoichiometry between tartrate oxidation and nitrate reduction were observed, indicating that the organism carried out a respiratory type of metabolism.     

Dissimilation of Methionine by Achromobacter starkeyi

Methionine was decomposed by some bacteria which were isolated from soil. The sulfur of the methionine was liberated as methanethiol, and part of this became oxidized to dimethyl disulfide. Detailed studies with one of these cultures, Achromobacter starkeyi, indicated that the first step in methionine decomposition was its oxidadative deamination to α-keto-γ-methyl mercaptobutyrate by a constitutive amino acid oxidase. The following steps were carried out by inducible enzymes, the synthesis of which was inhibited by chloramphenicol. α-Keto-γ-methyl mercaptobutyrate was split producing methanethiol and α-keto butyrate which was oxidized to propionate. The metabolism of propionate was similar to that described for animal tissues; the propionate was carboxylated to succinate via methyl malonyl coenzyme A, and the succinate was metabolized through the Krebs cycle.     

Dissimilation of aromatic compounds by Alcaligenes eutrophus

The range of aromatic compounds that support the growth of Alcaligenes eutrophus has been determined, and the pathways used for the dissimilation of these substrates have been explored, largely by enzymatic analyses. The beta-ketoadipate pathway operates in the dissimilation of benzoate and p-hydroxybenzoate; the genetisate pathway, in the dissimilation of m-hydroxybenzoate; and the meta cleavage pathway, in the dissimilation of phenol and p-cresol. l-Tryptophan is oxidized via anthranilate; but the metabolic fate of anthranilate was not established. The metabolism of the three stereoisomers of muconic acid was also examined.     

Formation of Dulcitol in Aerobic Dissimilation of d-Galactose by Yeasts

During the study of aerobic dissimilation of galactose by yeasts, polyhydric products were isolated in crystalline form from the fermented broths and identified. Yeast species may be divided into two groups on basis of sugar alcohol production: type I yeasts form the same end products from galactose as from glucose; type II yeasts produce dulcitol from galactose with or without other sugar alcohols but they produce no dulcitol from glucose. Isolation of dulcitol from microorganism has not been previously described.