Chain Formation in Œcophylla longinoda

The aggregation phenomenon is very common in numerous activities of social insects, however, it is often their functional aspects that are studied, leaving their mechanisms not so well understood. With the example of chain formation in cophylla longinoda, we present the mechanisms responsible for these collective structures. Our experimental results show that a change in the probability that a worker will decide to join or leave a chain is (1) strongly dependent on the number of ants present in the chain and (2) slightly dependent on the presence of a visual stimulus. The determining role of these probabilities is validated with the use of a mathematical model that reproduces the formation and breakup of the chain. Moreover, it predicts other properties of aggregation such as the influence of nest population size.     

Formation ofl-Alanine byStreptomyces coelicolor 3–19

Fermentative preparation ofl-alanine byStreptomyces coelicolor 3–19 was developed under laboratory conditions. In a medium containing glucose, corn-steep and mineral salts, the strain accumulated 9 gl-alanine per litre after four days of cultivation.     

Microbial Formation of D-Pantothenic Acid-α-glucoside

The formation of D-pantothenic acid-α-glucoside (PaA-α-G) was found from D-pantothenic acid (PaA) and maltose in incubation mixtures of microorganisms, especially Saccharomyces yeasts and Sporobolomyces coralliformis IFO 1032. The reaction conditions were investigated for formation of PaA-α-G by resting cells of Spor. coralliformis. The formation of the compound increased with PaA concentration (3~20 mg/ml). The yield was maximum at 5~10 mg/ml of PaA. Cetyl trimethyl ammonium bromide (0.1 %) promoted the formation of PaA-α-G. Sucrose was the optimal α-glucosyl donor. When 30 mg/ml of sucrose was fed to the reaction mixture (initial sucrose, 100 mg/ml; and PaA, 10 mg/ml) at 12-hr intervals, 5.74 mg/ml (3.30 mg/ml as PaA) of PaA-α-G was formed in 48-hr incubation at 28°C with shaking. PaA-α-G was also formed by yeast α-glucosidase, mold maltase and the cell-free extract of Spor. coralliformis. The compound showed approximately 9~10% and 0.1~0.3% (molar ratio) of activity of PaA for Saccharomyces carlsbergensis ATCC 9080 and Lactobacillus plantarum ATCC 8014, respectively. The compound had the same microbiological activity as authentic 4′-O-(α-D-glucopyranosyl)-D-pantothenic acid.     

Peroxynitrite-Dependent Aromatic Hydroxylation and Nitration of Salicylate and Phenylalanine. Is Hydroxyl Radical Involved?

There is considerable dispute about whether the hydroxylating ability of peroxynitrite (ONOO^-)-derived species involves hydroxyl radicals (OH*). This was investigated by using salicylate and phenylalanine, attack of OH* upon which leads to the formation of 2, 3- and 2, 5-dihydroxybenzoates, and o-, m- and p-tyrosines respectively. On addition of ONOO- to salicylate, characteristic products of hydroxylation (and nitration) were observed in decreasing amounts with rise in pH, although added products of hydroxylation of salicylate were not recovered quantitatively at pH 8.5, suggesting further oxidation of these products and underestimation of hydroxylation at alkaline pH. Hydroxylation products decreased in the presence of several OH* scavengers, especially formate, to extents similar to those obtained when hydroxylation was achieved by a mixture of iron salts, H₂O₂ and ascorbate. However, OH* scavengers also inhibited formation of salicylate nitration products. Ortho, p- and m-tyrosines as well as nitration products were also observed when ONOO^- was added to phenylalanine. The amounts of these products again decreased at high pH and were decreased by addition of OH* scavengers. We conclude that although comparison with Fenton systems suggests OH* formation, simple homolytic fission of peroxynitrous acid (ONOOH) to OH* and NO₂ would not explain why OH* scavengers inhibit formation of nitration products.     

Formation of amyloid fibrils from β-amylase

Fibril formation has been considered a significant feature of amyloid proteins. However, it has been proposed that fibril formation is a common property of many proteins under appropriate conditions. We studied the fibril formation of β-amylase, a non-amyloid protein rich in α-helical structure, because the secondary structure of β-amylase is similar to that of prions. With the conditions for the fibril formation of prions, β-amylase proteins were converted into amyloid fibrils. The features of β-amylase proteins and fibrils are compared to prion proteins and fibrils. Furthermore, the cause of neurotoxicity in amyloid diseases is discussed.     

Peptide Bond Formation via Nα-Protected Diacyldiselenides

International Journal of Peptide Research and Therapeutics - A simple, straightforward, for the peptide bond formation employing corresponding carboxylic acids and amines derived from amino acids...     

DNA Triple Helix Formation by N-Alkylphosphoramidate α-Oligonucleosides

Abstract

Triplex formation of pyrimidine N-alkylphosphoramidate α-oligonucleosides (12-mer) containing either dC or 5-Me-dC with their phosphodiester oligonucleoside homopurine target was evaluated by UV melting experiments.     

“Boundary Formation” Within Mutual Aid Assemblages

As grassroots user/survivor movements gained traction across the Global North, mental health activists have provided mutual aid for those who consider themselves to be negatively affected by their psychiatrization experiences and for those in search of alternative (non-biopsychiatric) frameworks for understanding mental diversity. In addition to in-person support groups, digital communication has become an integral organizing mechanism for mutual aid actions to support those in mental distress. However, activists have often found both digital and face-to-face communication to be quite taxing to their own well-being—as they negotiate personal capacity to respond to collective needs and practice self-care through limiting their engagements in radical mental health communities. While engaging in an ethnography with a mutual aid community in the United States, I explored the use of “boundary formation” to set parameters for social engagement within digital support and face-to-face encounters. Semi-structured interviews with 14 participants, focus group discussions, participatory observation, and an analysis of digital communication revealed that group members often discussed setting personal boundaries as an act of self-care, a recognition of the pitfalls associated with engaging in group dynamics during times of mental distress, and as a practice to ensure communal longevity. The ways that participants discussed and enacted boundary formation are analyzed in this paper as a way of blocking, redirecting, and restructuring digital and in-person engagements within mutual aid assemblages.

     

Biogenic Catalysis of Soil Formation on Mars?

The high iron abundance and the weak ferric iron spectral features of martian surface material are consistent with nanophase (nm-sized) iron oxide minerals as a major source of iron in the bright region soil on Mars. Nanophase iron oxide minerals, such as ferrihydrite and schwertmannite, and nanophase forms of hematite and goethite are formed by both biotic and abiotic processes on Earth. The presence of these minerals on Mars does not indicate biological activity on Mars, but it does raise the possibility. This work includes speculation regarding the possibility of biogenic soils on Mars based on previous observations and analyses. A remote sensing goal of upcoming missions should be to determine if nanophase iron oxide minerals, clay silicates and carbonates are present in the martian surface material. These minerals are important indicators for exobiology and their presence on Mars would invoke a need for further investigation and sample return from these sites.     

Rapid Myoglobin Aggregation through Glucosamine-Induced α-Dicarbonyl Formation

The extent of glycation and conformational changes of horse myoglobin (Mb) upon glycation with N-acetyl-glucosamine (GlcNAc), glucose (Glc) and glucosamine (GlcN) were investigated. Among tested sugars, the rate of glycation with GlcN was the most rapid as shown by MALDI and ESI mass spectrometries. Protein oxidation, as evaluated by the amount of carbonyl groups present on Mb, was found to increase exponentially in Mb-Glc conjugates over time, whereas in Mb-GlcN mixtures the carbonyl groups decreased significantly after maximum at 3 days of the reaction. The reaction between GlcN and Mb resulted in a significantly higher amount of α-dicarbonyl compounds, mostly glucosone and 3-deoxyglucosone, ranging from and 27 to 332 mg/L and from 14 to 304 mg/L, respectively. Already at 0.5 days, tertiary structural changes of Mb-GlcN conjugate were observed by altered tryptophan fluorescence. A reduction of metmyoglobin to deoxy-and oxymyoglobin forms was observed on the first day of reaction, coinciding with the greatest amount of glucosone produced. In contrast to native α-helical myoglobin, 41% of the glycated protein sequence was transformed into a β-sheet conformation, as determined by circular dichroism spectropolarimetry. Transmission electron microscopy demonstrated that Mb glycation with GlcN causes the formation of amorphous or fibrous aggregates, started already at 3 reaction days. These aggregates bind to an amyloid-specific dye thioflavin T. With the aid of α-dicarbonyl compounds and advanced products of reaction, this study suggests that the Mb glycation with GlcN induces the unfolding of an initially globular protein structure into amyloid fibrils comprised of a β-sheet structure.     

Formation of Non-Native ??-Lactoglobulin during Heat-Induced Denaturation

A mechanism describing the denaturation and aggregation behavior during heat-treatment of pure β-lactoglobulin and β-lactoglobulin in whey protein isolate (WPI) under selected conditions (20 to 90 gL⁻¹ in water at pH 7.0, 78 °C) is presented. A combination of reversed-phase and gel permeation chromatography was used to study the disappearance of native β-lactoglobulin and the formation of non-native intermediates in the aggregation process. The mean reaction order for pure β-lactoglobulin and β-lactoglobulin in WPI were the same, 1.4. While the rate of β-lactoglobulin denaturation was greater in WPI there was less aggregation compared to that of pure β-lactoglobulin. More of the β-lactoglobulin in WPI remained in a non-native monomer intermediate state after 30 min of heating. After an initial lag period, during which non-native monomers appeared, aggregates formed and rapidly reached a plateau in terms of their size. These aggregates were visualized using atomic force microscopy. There was no significant effect of protein concentration on either aggregate size or the number of exposed sulfhydryls in the heated solutions.     

5′-Phosphodiesterase Formation by Cultured Plant Cells

5′-Phosphodiesterase (5′-PDase) which degrades RNA to nucleoside-5′-monophosphates was investigated in various kinds of plant calli, and the calli of Vinca rosea and Phytolacca americana were found to have the high activity. The liquid culture conditions of the cells of V. rosea were examined. Three mg of kinetin and 0.5 mg of 2,4-dichlorophenoxyacetic acid per liter in the Murashige and Skoog medium were optimal for the growth and the 5′-PDase formation. Under the optimal conditions, time courses of the cell growth and the enzyme formation were measured.

The 5′-PDase of the cultured cells of V. rosea in suspension showed the maximal activity at pH 8.0 and 60°C. A comparison of 5′-PDase of the cultured cells and of the mother plant of V. rosea was carried out and it was found that the cultured cells had more than 30 times as much 5′-PDase activity as the mother plant on dry cell weight basis.     

Salt Effects on Plastein Formation by α-Chymotrypsin

The plastein formation by α-chymotrypsin from an ovalbumin hydrolysate was affected in an order of valency of salts when the concentration of each salt was 1 m. Monovalent cations were rather effective at this concentration and enhanced the plastein yield by 10%. In the presence of NaCl, the plastein formation showed two distinct maximal rates at its concentrations of 0.1 m and 0.8 m. The first maximum was considered to be resulted from an increase in enzyme activity, since chymotryptic hydrolysis of both N-acetyl-l-tyrosine ethyl ester and benzyloxycarbonyl-l-phenylalanine p-nitrophenyl ester was activated at an NaCl concentration of 0.1 ~ 0.2 m. The second maximum was ascribed to the salting-out of the product due to the higher concentration of NaCl. A salt-tolerant protease was also used to confirm the above conclusions. It was observed that this enzyme was much effective in producing a plastein at a high NaCl concentration. This may be due to the fact that both the enzyme activation effect and the product salting-out effect participate co-operatively.     

Production of Hydroxyl Radicals and α-dicarbonyl Compounds Associated with Amadori Compound-Cu 2+ Complex Degradation

The chemical properties of Amadori compounds in the presence of transition metal ions were studied, using the analogs 1-deoxy-1- n -butylamino- d -fructose (DBF) and N &#102 -formyl-fructoselysine (fFL). The following characteristics were revealed: (a) DBF combined easily with Cu 2+ (but no other transition metal ions) to form a DBF-Cu 2+ complex in phosphate buffer, pH 7.4; (b) the complex was unstable, and degraded with the release of Cu + during incubation at 37°C; (c) degradation of the complex was associated with the production of hydroxyl radicals by the Fenton reaction and &#102 -dicarbonyl compounds by non-autoxidative degradation; and (d) properties of DBF were similar to those of fFL. The above properties were additionally observed in glycated poly-Lys (GPL). Our findings indicate a novel mechanism for the generation of hydroxyl radicals and &#102 -dicarbonyl compounds from Amadori adducts in the presence of Cu 2+ .     

Enzyme-Induced Formation of β-Lactoglobulin Fibrils by AspN Endoproteinase

This paper describes a low temperature, enzymatic route to induce fibrillar structures in a protein solution. The route comprises two steps. First, β-lactoglobulin was hydrolyzed into peptides at pH 8 and 37 °C with the enzyme AspN endoproteinase, which resulted in the formation of random aggregates. After hydrolysis, the pH was lowered to 2. As a result, long fibrillar aggregates were formed which was observed using transmission electron microscopy and Thioflavin T fluorescence measurements.     

Condensation Reaction Occurring during Plastein Formation by α-Chymotrypsin

An investigation was conducted on myosin and actin-activated heavy meromyosin (HMM) ATPase activities in normal porcine muscle stored for varying periods of time after death. Studies were also made on temperature dependent myosin ATPase, initial burst of ATPase and actin-activated HMM ATPase in normal and in pale, soft and exudative (PSE) porcine muscle. The maximum velocity of acto-HMM ATPase of normal muscle decreased considerably with postmortem time, while the apparent dissociation constant decreased slightly. The maximum velocity of acto-HMM ATPase of postmortem normal muscle was approximately two-times larger than that of the corresponding PSE muscle. However, almost no difference was found in the apparent dissociation constant. The size of the initial burst of phosphate-liberation of myosin prepared from normal muscle was approximately 1.2 mol/mol of myosin and from PSE muscle 0. It is assumed that the lack of contractility of PSE muscle was brought about by two basic myosin malfunctions: one, the irreversible binding of myosin to actin filament and the other, the functional damage of myosin ATPase, responsible for the formation of phosphorylated complex, even when dissociable.     

Ester Formation by Alcohol Acetyltransferase from Brewers’ Yeast

Alcohol acetyltransferase responsible for the formation of acetate esters during beer fermentation was found to be localized at the cell membrane of brewers’ yeast. This cell membrane-bound enzyme was purified 120-fold by solubilization with Triton X-100, gel filtration on a Sepharose 6B column and chromatography on a DEAE-Sephadex A-50 column. The enzyme was most active at 30°C at pH 7 ? 8. It was least active against C₃ alcohol among C₁ ? C₆ alcohols, and slightly more active against straight-chain alcohols than against branched-chain alcohols with the same carbon number. The enzyme was strongly inhibited by unsaturated fatty acids, heavy metal ions and sulfhydryl reagents.     

The Critical Aggregation Concentration of β-Lactoglobulin-Based Fibril Formation

The critical aggregation concentration (CAC) for fibril formation of β-lactoglobulin (β-lg) at pH 2 was determined at 343, 353, 358, 363, and 383 K using a Thioflavin T assay and was approximately 0.16 wt%. The accuracy of the CAC was increased by measuring the conversion into fibrils at different stirring speeds. The corresponding binding energy per mol, as determined from the CAC, was 13 RT (∼40 kJ mol⁻¹) for the measured temperature range. The fact that the CAC was independent of temperature within the experimental error indicates that the fibril formation of β-lg at pH 2 and the measured temperature range is an entropy-driven process.     

Pyruvate Decarboxylase Catalysed Formation of Terpenoid α-hydroxy Ketones

Enzyme extracts of the wild type yeast Zygosaccharomyces bisporus were applied for the pyruvate decarboxylase catalysed condensation of pyruvate and (R)-(+)-and (S)-(?)-perillyl aldehyde, (±)-citronellal, neral, geranial or (R)-(?)-myrtenal to form novel α-hydroxy ketones. Best yields were obtained when the transformation medium contained 25% (v/v) of the cosolvent N,N-dimethylformamide. Conversion of (R)-(+)-perillyl aldehyde to (1R)-1-hydroxy-1-[(4’R)-4’-isopropenyl-1-cyclohexen-1-yl]-2-propanone proceeded highly stereospecifically (>99% de), whereas the stereoselectivity was somewhat less in the transformation of (S)-(?)-perillyl aldehyde (58% de) and (R)-(?)-myrtenal (92% de). All of the new compounds imparted characteristic odour impressions as determined by means of GC-olfactometry.     

Formation of β-sheets in glutamine and alanine tripeptides

The misfolding and aggregation of proteins is associated with many different diseases including the trinucleotide repeat disorders and Prion diseases. We have studied three residue peptides comprising alanine and glutamine in order to understand the short range interactions affecting the formation of β-rich aggregates. Using infrared spectroscopy, we have found that trialanine and triglutamine form significant amounts of β-sheet, but that tripeptides containing alanine and glutamine are only able to form β-sheet if the glutamine side-chains extend outward on both faces of the sheet. From our data, we conclude that different stabilizing interactions are responsible for β-sheet formation in trialanine and triglutamine.