Amino Acid Sequence of αkSubstance,a Mating Pheromone of Saccharomyces kluyveri

A fraction containing IgA (IgA-rich fraction) was prepared from bovine colostrum by anion exchange chromatography using DEAE-Sephadex A-50 and gel filtration on Sephadex G-200. A large amount of IgG1-dimer was found in this fraction, which could not be separated from IgA by repeated gel filtration.

The Fc fragment of bovine colostral IgG (IgG-Fc) was prepared from papain digestion mixtures. IgG-Fc was found to be heterogeneous on DEAE-cellulose column chromatography. Two IgG-Fc fractions were obtained, but no antigenic difference was found between them. Anti-IgG-Fc antibodies raised in rabbits by injection of these Fc preparations reacted only with IgG1 and IgG2. An immunoadsorbent (anti-IgG-Fc-Sepharose) was prepared by coupling these anti-IgG-Fc antibodies to CNBr-activated Sepharose 4B.

IgA was purified from the IgA-rich fraction by affinity chromatography on anti-IgG-Fc-Sepharose adsorbent. IgG1-dimer was effectively removed by this treatment. The purified sample gave only one precipitin arc characteristic of IgA on immunoelectrophoresis with multiple anti-bovine colostral whey antiserum. A small amount of IgA was found to be adsorbed to the affinity column nonspecifically.

When a rabbit was immunized with the purified IgA, besides anti-IgA antibodies, antibodies against the secretory component (SC) were found in the antiserum. This finding leads us to expect that the purified IgA is secretory IgA containing SC.     

Racemization of the Aspartic Acid Residue of Amyloid-β Peptide by a Radical Reaction

An E. coli cell extract containing thermostable α-amylase and maltogenic amylase expressed from the clone pTMA322 was used to produce an anomalously linked oligosaccharides (Alo) mixture from starch. The liquefaction and saccharification of starch were done by one-step procedure using the above cell extract. The resulted Alo mixture contained over 40% oligosaccharides having DP 3 or more including branched forms.     

Characteristics of the Deoxyribonucleic Acid of Tφ3, a Bacteriophage for Bacillus stearothermophilus

It is shown that the individual strands of bacteriophage Tphi3 DNA are intact and that heat-denatured Tphi3 DNA forms a bimodal distribution in a neutral CsCl density gradient.     

Isolation of a New Intermediary Substance Consisting of Colistin Fatty Acid and l-α,δ-Diaminobutyric Acid from Colistin-producing Cells of Bacillus colistinus Koyama

Several saccharides were found to be significantly effective in providing protection against hydrostatic pressure and high temperature damage in the yeast Saccharomyces cerevisiae. The extent of barotolerance and thermotolerance with seven different sugars showed a linear relationship to their mean number of equatorial OH groups. The same linear relatioship is seen when sugars protect protein molecules against elevated temperatures in vitro. Some sugars were more effective in providing protection against hydrostatic pressure nearly a hundred times than high temperature. Pre-heat shock treatment on yeast cells induce various stress tolerances. In this report, pre-heat shocked cells showed potent protection against elevated temperature, but these cells showed faint protection against elevated pressure.

These results suggest that sugars may protect cells against hydrostatic pressure and high temperature in a similar manner, probably by stabilizing the macromolecule(s), and such type of protection may be suited for pressure stress.     

Are Roots a Source of Abscisic Acid for the Shoots of Flooded Pea Plants?

Flooding the soil for 2–5 d decreased stomatal conductancesof pea plants (Pisum sativum L., cv. Sprite) with six or sevenleaves. This coincided with slower transpiration, increasedleaf water potentials and increased concentrations of abscisicacid (ABA) in the leaves. No increase in ABA was found in theterminal 20 mm of roots of flooded plants over the same timeperiod. Small stomatal conductances associated with increases in foliarABA were also found in plants grown in nutrient solution whenaeration was halted, causing the equilibrium partial pressuresof dissolved oxygen to fall below 05 It Pa. No increase in ABAconcentration in young secondary roots of the non-aerated plantswas detected after 24, 48 or 72 h, even when the shoot, thepresumed site of deposition for any ABA from the roots, wasremoved 5–6 h before analysis. Similarly, ABA concentrations in roots were not increased whenthe nutrient solution was de-oxygenated by continuous purgingwith nitrogen gas. The abscisic acid concentration in leaf epidermis,the tissue most likely to be the recipient of any ABA movingin the transpiration stream from oxygen-deficient roots, waslower than in the remaining parts of the leaf when examinedin the mutant Argenteum which possesses easily removable epidermallayers. It is concluded that the leaves of plants subjectedto flooding of the soil or oxygen shortage in the root environmentare not enriched substantially with ABA from the roots. A moreprobable source of this growth regulator is the leaf itself. Key words: Pisum sativum, flooding, roots, hormones, aeration stress, abscisic acid, Argenteum mutant     

Oligomerization of α-Thioglutamic Acid

A decaglutamic acid primer is extended very slowly by-thioglutamic acid. The addition of bicarbonate to thereaction mixture greatly accelerates the reaction. We believethe N-carboxyanhydride of glutamic acid is an intermediate inthe accelerated reaction. When K₃Fe(CN)₆ andbicarbonate are both present in the reaction mixture,oligoglutamic acids up to at least the 15-mer are formedrapidly. The acylating agent is the oxidation product ofthioglutamic acid, a diacyldisulfide.     

Microbial Degradation of α-Picolinic Acid, 2-Pyridinecarboxylic Acid

The biological effects of raw winged bean seeds were investigated with feeding experiments on rats, and the effects of lectin (phytohemagglutinin) present in the seeds are discussed. Administration of a 30% raw winged bean diet caused strong growth depression in young rats, and led to death within 10 ~ 20 days, inducing severe damage to the small intestine of the rats. Significant morphological changes of the intestinal mucosa were observed with a microscopic investigation. As the lethal effect was eliminated by autoclaving but not removed with supplementation of 0.5% l-methionine to the raw winged bean diet, the lectin was assumed to be closely related to the deleterious effects of raw winged bean. In vitro and in vivo digestion tests of the lectin revealed that the winged bean lectin had resistance to peptic, pancreatic and membrane digestions. The hemagglutinating activity was also detected in the intestinal mucosa and faeces from rats ingesting the raw winged bean or its purified lectin. The binding action of lection to mucosal epitheliums of the gastrointestinal tract is suggested to be the initial step of the deleterious effects induced by the winged bean lectin.     

α-Aminoisobutyric Acid as the Constituent Amino Acid of Protein

α-Aminoisobutyric acid is the only tertiary amino acid which is reported to occur in the proteins. Nevertheless, this amino acid has not been yet isolated from the proteins. Recently we succeeded in isolating this amino acid as white prismy crystalline substance from both acid and pepsin hydrolysate of horse hind leg muscle proteins, and this crystal was identified to be α-amino-isobutyric acid by elementary analysis, properties of this derivates, etc.     

Monodehydro-2,2′-iminodi-2(2′)-deoxy-l-ascorbic Acid,a Radical Product from the Reaction of Dehydro-l-ascorbic Acid with an α-Amino Acid

One of the radical species produced by the reaction of dehydro-l-ascorbic acid with an α-amino acid gave a very characteristic hyperfine structure in its electron spin resonance spectrum. The same spectrum was also obtained when l-scorbamic acid was oxidized with some oxidants, indicating the formation of the radical via the oxidation of l-scorbamic acid. From the results of deuterium exchange experiments, simulation spectra and the reduction of 2,2′-nitrilodi-2(2′)-deoxy-l-ascorbic acid monoammonium salt, the radical was concluded to be monodehydro-2,2′-iminodi-2(2′)-deoxy-l-ascorbic acid. Possible formation mechanism of the radical was also discussed.     

Replication of Bacteriophage φX174 in a Temperature-Sensitive Deoxyribonucleic Acid Host Cell

Bacteriophage phiX174 is unable to replicate in Escherichia coli t3 at the restrictive temperature. However, if progeny phage synthesis is initiated at the permissive temperature, it will continue after a shift to the restrictive temperature.     

Novel Properties of a Mouse γ-Aminobutyric Acid Transporter (GAT4)

We expressed the mouse gamma-aminobutyric acid (GABA) transporter GAT4 (homologous to rat/ human GAT-3) in Xenopus laevis oocytes and examined its functional and pharmacological properties by using electrophysiological and tracer uptake methods. In the coupled mode of transport (Na+/ Cl-/GABA cotransport), there was tight coupling between charge flux and GABA flux across the plasma membrane (2 charges/GABA). Transport was highly temperature-dependent with a temperature coefficient (Q10) of 4.3. The GAT4 turnover rate (1.5 s(-l); -50 mV, 21 degrees C) and temperature dependence suggest physiological turnover rates of 15-20 s(-1). No uncoupled current was observed in the presence of Na+. In the absence of external Na+, GAT4 exhibited two distinct uncoupled currents. (i) A Cl- leak current (ICl(leak)) was observed when Na+ was replaced with choline or tetraethylammonium. The reversal potential of (ICl(leak)) followed the Cl- Nernst potential. (ii) A Li+ leak current (ILi(leak)) was observed when Na+ was replaced with Li+. Both leak currents were inhibited by Na+, and both were temperature-independent (Q10 approximately 1). The two leak modes appeared not to coexist, as Li+ inhibited (ICl(leak)). The results suggest the existence of cation- and anion-selective channel-like pathways in GAT4. Flufenamic acid inhibited GAT4 Na+/Cl-/GABA cotransport, ILi(leak), and ICl(leak), (Ki approximately 30 microM), and the voltage-induced presteady-state charge movements (Ki approximately 440 microM). Flufenamic acid exhibited little or no selectivity for GAT1, GAT2, or GAT3. Sodium and GABA concentration jicroumps revealed that slow Na+ binding to the transporter is followed by rapid GABA-induced translocation of the ligands across the plasma membrane. Thus, Na+ binding and associated conformational changes constitute the rate-limiting steps in the transport cycle.     

Is Salicylic Acid a Translocated Signal of Systemic Acquired Resistance in Tobacco?

Salicylic acid (SA) is a likely endogenous signal in the development of systemic acquired resistance (SAR) in some dicotyledonous plants. In tobacco mosaic virus (TMV)-resistant Xanthi-nc tobacco, SA levels increase systemically following the inoculation of a single leaf with TMV. To determine the extent to which systemic increases in SA result from SA export from the inoculated leaf, SA produced in TMV-inoculated or healthy leaves was noninvasively labeled with 18O2. Spatial and temporal distribution of 18O-SA indicated that most of the SA detected in the healthy tissues was synthesized in the inoculated leaf. No significant increase in the activity of benzoic acid 2-hydroxylase, the last enzyme involved in SA biosynthesis, was detected in upper uninoculated leaves, although the basal level of enzyme activity was relatively high. No increases in SA level, pathogenesis-related PR-1 gene expression, or TMV resistance in the upper uninoculated leaf were observed if the TMV-inoculated leaf was detached up to 60 hr after inoculation. Apart from the inoculated tissues, the highest increase in SA was observed in the leaf located directly above the inoculated leaf. The systemic SA increase observed during SAR may be explained by phloem transport of SA from the inoculation sites.     

In Vivo Anti-Tumor Activity of a New Doxorubicin Conjugate via α-Linolenic Acid

The conventional chemotherapy agent, doxorubicin, is of limited clinical use because of its systemic toxicity toward normal healthy tissue. A new doxorubicin conjugate with α-linolenic acid showed good anti-tumor activity with lower toxicity than free doxorubicin and exhibited an active tumor-targeting profile due to the introduction of α-linolenic acid which might be an effective tumor-targeting moiety for the modification of chemotherapeutics.     

Synthesis of 4′-(Hydroxymethyl)Guanosine and a Phosphonate Analogue of Guanylic Acid

Abstract

The synthesis of 4′-(hydroxymethyl)guanosine (7) and the phosphonate analogue 8 of guanylic acid proceed from a common intermediate, 2′, 3′-O-isopropylidene-N ²-(monomethoxytrityl)-guanosine-5′-aldehyde (13).