Effect of ischemia,calcium depletion and repletion,acidosis and hypoxia on cellular taurine content

Summary.  Occlusion of the left main coronary artery led to a time-dependent release of taurine from the heart. Upon reperfusion, there was a second phase of taurine release, which exceeded the amount of taurine that exited the heart during the 45 min ischemic insult. To obtain information on the mechanism underlying the release of taurine, three variables were examined, acidosis, hypoxia and calcium overload. It was found that large amounts of taurine also leave the cell during the calcium paradox, a condition induced by perfusing the heart with calcium containing buffer following a period of calcium free perfusion. However, little taurine effluxes the hearts exposed to buffer whose pH was lowered to 6.6. Isolated neonatal cardiomyocytes subjected to chemical hypoxia also lost large amounts of taurine. However, the amount of taurine leaving the cells appeared to be correlated with the intracellular sodium concentration, [Na⁺]_i. The data suggest that taurine efflux is regulated by [Na⁺]_i and cellular osmolality, but not by cellular pH. Received November 15, 2001 Accepted January 15, 2002 Published online October 3, 2002 Acknowledgements This study was supported with a grant from the Taisho Pharmaceutical Company. Authors' address: Dr. Stephen W. Schaffer, Department of Pharmacology, University of South Alabama, School of Medicine, Mobile, Alabama, U.S.A., E-mail: sschaffe@jaguarl.usouthal.edu     

Aryl alcohol oxidases from the white-rot basidiomycete Pleurotus ostreatus

 Three aryl alcohol oxidases (AAOs; EC 1.1.3.7) I, II, and III from the culture filtrate of a strain of white-rot fungus Pleurotus ostreatus were purified by multistep chromatography. Each of the purified AAOs I, II, and III had the same molecular masses of 70 kDa and 72 kDa on gel filtration chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, respectively. Their optimum temperature was 40°C, but their optimum pHs differed slightly. The N-terminal amino acid sequence of AAOs I, II, and III was determined to be Ala-Asp-Lys-Asp-Tyr-Ile-Val-Val-Gly-Ala, which showed significant similarity to those of Pleurotus eryngii (80% identity) and Pleurotus ostreatus Florida (60% identity). Received: May 30, 2002 / Accepted: July 10, 2002 Acknowledgment This work was supported in part by a Grant-in-Aid for the Encouragement of Young Scientists (no. 12760117) from the Ministry of Education, Culture, Sports, Science and Technology, Japan. Correspondence to:K. Okamoto     

Mitochondrial nitric oxide inhibits ATP synthesis. Effect of free calcium in rat heart

Summary.  Nitric oxide is a small potentially toxic molecule and a diatomic free radical. We report the interaction of L-arginine, oxygen and calcium with the synthesis of nitric oxide in heart mitochondria. Nitric oxide synthesis is increased in broken rat heart mitochondria compared with intact and permeabilized mitochondria. Intact mitochondria subjected to hypoxia-reoxygenation conditions accumulated nitric oxide that inhibits oxygen consumption and ATP synthesis. ATPase activity is not affected during this augment of nitric oxide. Physiological free calcium concentrations protected mitochondria from the damage caused by the accumulation of nitric oxide. Higher concentrations of the divalent cation increase the damage exerted by nitric oxide. Received April 15, 2002 Accepted June 17, 2002 Published online November 14, 2002 Acknowledgements This work was supported in part by Mexican Grants from CONACYT (to A.S.M. during its sabbatical) and CIC-UMSNH (2.5). Authors' address: Alfredo Saavedra-Molina, Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Edificio B-3. C.U., Morelia, Mich. 58030, México, Fax: 52-443-326-5788, E-mail: saavedra@zeus.umich.mx     

Phosphate-dependent glutaminase in enterocyte mitochondria and its regulation by ammonium and other ions

Summary.  The effects of ammonium and other ions on phosphate dependent glutaminase (PDG) activity in intact rat enterocyte mitochondria were investigated. Sulphate and bicarbonate activated the enzyme in absence and presence of added phosphate. In presence of 10 mM phosphate, ammonium at concentrations <1 mM inhibited the enzyme. This inhibition was reversed by increased concentration of phosphate or sulphate. The inhibition of PDG by ammonium in presence of 10 mM phosphate was biphasic with respect to glutamine concentration, its effect being through a lowering of V_max at glutamine concentration of ≤5 mM, and increased K_m for substrate concentration above 5 mM. The activation of the enzyme by bicarbonate was through an increase in V_max. Ammonium and bicarbonate ions may therefore be important physiological regulators of PDG. It is suggested that phosphate and other polyvalent ions may function by preventing product inhibition of the enzyme through promotion of PDG dimer formation. The dimerized enzyme may have a high affinity for glutamine and reduced sensitivity to inhibition by ammonium ions. Received August 10, 2001 Accepted April 1, 2002 Published online August 30, 2002 Acknowledgement This work was supported by University of Zimbabwe research grant to Dr. B. Masola. Authors' address: Dr. Bubuya Masola, Department of Biochemistry, University of Zimbabwe, P O Box MP167, Mount Pleasant, Harare, Zimbabwe, E-mail: masolab@yahoo.co.uk     

Synthesis and paralytic activities of squaryl amino acid-containing polyamine toxins

Summary.  Eight analogs 4a-7a and 4b-7b of philanthotoxin (PhTX) from wasp venom and nephilatoxin-8 (NPTX-8) from spider venom whose tyrosine or asparagine linker is replaced by squaryl (sq) amino acid or 4-amino squaryl (4-asq) amino acid have been synthesized in an efficient manner via coupling of N-acyl squaryl amino acid intermediate 19 or 26 with the corresponding polyamine part. Preliminary bioassay using crickets revealed that the analogs substituted by glutamate-type squaryl amino acid-containing NPTX 7a and 7b showed more potent paralytic activities than that of NPTX-8. Received April 25, 2002 Accepted June 21, 2002 Published online December 18, 2002 Acknowledgement This work was supported by a grant from Research for the Future Program from the Japan Society for the Promotion of Science (JSPS). Authors' address: Yasufumi Ohfune, Graduate School of Science, Osaka City University, Sugimoto, Osaka 558-8585, Japan, Fax: +81-6-6605-3153, E-mail: ohfune@sci.osaka-cu.ac.jp     

A hypothesis on the biochemical mechanism of BH<Subscript>4</Subscript>-responsiveness in phenylalanine hydroxylase deficiency

Summary.  We describe six children with tetrahydrobiopterin (BH₄) responsive phenylalanine hydroxylase (PAH) deficiency. All patients carry two mutant alleles in the PAH gene. Cofactor deficiency was excluded. The effect of BH₄ administration was studied by correlating different oral BH₄ doses with plasma phenylalanine levels under defined protein intake. Our results indicate that oral BH₄ supplementation may be used as long-term treatment for individuals with BH₄-responsive PAH deficiency, either without or in combination with a less restrictive diet. Previous in vitro studies have demonstrated that BH₄ inhibits PAH tetramers but activates PAH dimers. This may indicate, that BH₄-responsiveness results from BH₄ induced stabilization of mutant PAH dimers. In addition, interindividual differences in the cellular folding apparatus may determine the tertiary structure and the amount of mutant PAH dimers and hence may account for divergent BH₄-responsiveness reported for the same PAH genotype. Received September 7, 2002 Accepted December 16, 2002 Published online March 17, 2003 Acknowledgements We express our gratitude to Dr. J. Zschocke for the genetic analysis of the PAH mutants, to Dr. N. Blau (Switzerland) for pterin analysis and to Dr. V. Wagner (Univ. Lübeck, Germany) for additional data on patient EM. Furthermore, we thank the technical staff of our laboratories for their accurate work throughout the project. Authors' address: Dr. Zoltan Lukacs, Metabolic Laboratory, Department of Pediatrics, University of Hamburg, Martinistr. 52, D-20246 Hamburg, Germany, Fax: +49-40-42803 6717, E-mail: Lukacs@uke.uni-hamburg.de List of abbreviations: BH₄, Tetrahydrobiopterin; DGGE, Denaturing gradient gel electrophoresis; DHPR, Dihydropteridine reductase; HPA, Hyperphenylalaninemia; MHP, Mild hyperphenylalaninemia; PAH, Phenylalanine hydroxylase; Phe, Phenylalanine; PKU, Phenylketonuria; Tyr, Tyrosine     

Effect of trehalose on the spawn storage in some edible mushroom fungi (2): Effect on preservation in the freezer

 We describe the effects of trehalose on spawn storage in a home freezer (average temperature, −16°C) where edible fungi usually do not survive. When the mycelia of Lentinula edodes were stored in a freezer for 3 days, the survival rate of mycelia cultivated on 2% glucose medium was 30%, whereas those on media containing 2% and 5% trehalose were 50% and 60%, respectively. Addition of trehalose to the culture was more effective in Pleurotus ostreatus. These results suggest that trehalose played the role of a stress protectant against freezing, because the mycelia cultured on a trehalose medium grew more rapidly and produced more fruiting bodies compared to those cultured on glucose. Received: February 6, 2002 / Accepted: October 1, 2002 Acknowledgments This work was partially supported by a Grant in Aid for Scientific Research (c) (2) No. 12660156 from the Japan Society for the Promotion of Science. We also gratefully acknowledge a grant from Hokuto Foundation for the Promotion of Biological Science. Correspondence to:T. Terashita     

Taurine chloramine modulates cytokine production by human peripheral blood mononuclear cells

Summary.  The effect of taurine (Tau) and taurine chloramine (Tau-Cl) on the production of TNF-α, IL-1β, and IL-6 by peripheral blood mononuclear cells of healthy volunteers was examined. Cells were stimulated with bacterial lipopolysaccharide (LPS) in the presence of either Tau or Tau-Cl. After 24 h culture the cytokine concentrations were measured in both culture supernatants (secreted) and cell lysates (cell-associated) using ELISA. In LPS-stimulated cells Tau-Cl inhibited both the secreted and cell-associated IL-1β and IL-6, while exerted dual effect on TNF-α production: raising it slightly at low and reducing at higher concentration. By contrast, Tau had no significant effect on the cytokine production. These results indicate that Tau-Cl modulates synthesis of pro-inflammatory cytokines, and therefore it may play a role in the initiation and propagation of immune response. Received November 29, 2001 Accepted January 18, 2002 Published online August 30, 2002 Acknowledgments This research was supported by grants from the State Committee for Scientific Research of Poland (No 4 P05B 01018) and the Institute of Rheumatology (No I/14). The Institute of Rheumatology is supported by a core grant from the State Committee for Scientific Research of Poland. Authors' address: Ewa Kontny, Ph.D., Department of Pathophysiology and Immunology, Institute of Rheumatology, Spartanska 1, 02-637 Warsaw, Poland, E-mail: zpatiir@warman.com.pl Abbreviations: Tau, taurine; Tau-Cl, taurine chloramine; LPS, lipopolysaccharide; TNF-α, tumor necrosis factor-α; IL-1β, interleukin 1β; IL-6, interleukin 6; PBMC, peripheral blood mononuclear cells     

Asymmetric synthesis of all stereoisomers of 6-methylpipecolic acids

Summary.  Asymmetric synthesis of all four stereoisomers of 6-methylpipecolic acids with high enantiomeric purity via iterative AD reaction, starting from 1,6-heptadiene, has been described. Received March 25, 2002 Accepted June 15, 2002 Published online January 30, 2003 Authors' address: Hiroki Takahata, Faculty of Pharmaceutical Sciences, Tohoku Pharmaceutical University, Sendai 981-8558, Japan, E-mail: takahata@tohoku-pharm.ac.jp RID="*" ID="*"  The stereo-configurations of 8 and 9 in Fig. 3 and 12 in Fig. 4 show only major isomers. RID="**" ID="**"  The absolute configurations of 11 and 14     

Spike timing dependent synaptic plasticity in biological systems

 Association of a presynaptic spike with a postsynaptic spike can lead to changes in synaptic efficacy that are highly dependent on the relative timing of the pre- and postsynaptic spikes. Different synapses show varying forms of such spike-timing dependent learning rules. This review describes these different rules, the cellular mechanisms that may be responsible for them, and the computational consequences of these rules for information processing and storage in the nervous system. Received: 16 January 2002 / Accepted: 3 June 2002 Acknowledgements. This research is supported in part by a National Science Foundation grant IBN 98-08887 (awarded to PDR), and by National Institutes of Health grants R01-MH49792 (awarded to CCB), R01-MH60996 (awarded to CCB), and R01-MH60996 (awarded to PDR). Correspondence to: P. D. Roberts (e-mail: robertpa@ohsu.edu)     

Neural computations in the tiger salamander and mudpuppy outer retinae and an analysis of GABA action from horizontal cells

 A neural network architecture based on the neural anatomy and function of retinal neurons in tiger salamander and mudpuppy retinae is proposed to study basic aspects of early visual information processing. The model predictions for the main response characteristics of retinal neurons are found to be in agreement with neurophysiological data, including the antagonistic role of horizontal cells in the outer plexiform layer. The examination of possible γ-aminobutyric acid (GABA) action from horizontal cells suggests that GABA_A alone, GABA_B alone, or their weighted combination can generate the response characteristics observed in bipolar cells. Received: 25 June 2002 / Accepted: 28 January 2003 / Published online: 20 May 2003 Acknowledgements. The authors would like to thank an anonymous reviewer for valuable comments. Correspondence to: S. X. Yang (e-mail: syang@uoguelph.ca)     

New development in the tritium labelling of peptides and proteins using solid catalytic isotopic exchange with spillover-tritium

Summary.  The mechanism of the reaction of high temperature solid state catalytic isotope exchange (HSCIE) of hydrogen in peptides with spillover-tritium at 140–180°C was analyzed. This reaction was used for preparing [³H]enkephalins such as [³H]DALG with specific activity of 138 Ci/mmol and [³H]LENK with specific activity of 120 Ci/mmol at 180°C. The analogues of [³H]ACTG_4–10 with specific activity of 80 Ci/mmol, [³H]zervamicin IIB with specific activity of 70 Ci/mmol and [³H]conotoxin G1 with specific activity 35 Ci/mmol were produced. The obtained preparations completely retained their biological activity. [³H]Peptide analysis using ³H NMR spectroscopy on a Varian UNITY-600 spectrometer at 640 MHz was carried out. The reaction ability of amino fragments in HSCIE was shown to depend both of their structures and on the availability and the mobility of the peptide chain. The reaction of HSCIE with the β-galactosidase from Termoanaerobacter ethanolicus was studied. The selected HSCIE conditions allow to prepare [³H] β-galactosidase with specific activity of 1440 Ci/mmol and completely retained its the enzymatic activity. Received November 30, 2001 Accepted January 31, 2002 Published online December 18, 2002 Acknowledgments The work was supported by the Russian Foundation for Basic Research, grant 01-04-48519a. Authors' address: Dr. Yurii A. Zolotarev, Institute of Molecular Genetics, Russian Academy of Sciences, pl. Kurchatova 2, 123182, Moscow, Russia, Fax: +7 (095) 196-0221, E-mail: zolya@img.ras.ru Abbreviations: HSCIE, the reaction of high temperature solid state catalytic isotope exchange; HS, hydrogen spillover; ³H NMR, tritium nuclear magnetic spectroscopy; CtxG1, conotoxin G1; AchR, acetylcholine receptor; HF, Hartree-Fock ab initio quantum-chemical calculation method     

Impaired generation of taurine chloramine by synovial fluid neutrophils of rheumatoid arthritis patients

Summary.  Taurine (Tau), a dominant free amino acid present in neutrophil cytoplasm, serves as a scavenger for hypochlorous acid (HOCl) released during these cells activation. The resulting taurine chloramine (Tau-Cl) exerts potent anti-inflammatory properties. In the present study we tested the hypothesis that the formation of Tau-Cl is impaired in neutrophils isolated from rheumatoid arthritis (RA) patients. The inhibition of zymosan-triggered chemiluminescence in the presence of exogenous Tau was used for indirect measurement of Tau-Cl generation. The chemiluminescence of neutrophils isolated from peripheral blood (PB) of healthy volunteers and RA patients was inhibited by Tau with similar potency. By contrast, synovial fluid (SF) neutrophils of these patients were significantly less sensitive for Tau-mediated inhibition. Therefore, our data indicate impaired generation of Tau-Cl in neutrophils isolated from SF of RA patients. Received November 29, 2001 Accepted January 9, 2002 Published online August 30, 2002 Acknowledgements This work was supported by grants from the State Committee for Scientific Research of Poland (No. P05A 104 19) and the Institute of Rheumatology. The Institute of Rheumatology is supported by a core grant from the State Committee for Scientific Research of Poland. Authors' address: Ewa Kontny, Ph.D, Department of Pathophysiology and Immunology, Institute of Rheumatology, Spartanska 1, 02-637 Warsaw, Poland, E-mail: zpatiir@warman.com.pl Abbreviations: Tau, taurine; Tau-Cl, taurine chloramine; PB, peripheral blood; SF, synovial fluid; RA, rheumatoid arthritis     

High constitutive peroxidase activity and constitutive thermotolerance in <Emphasis Type="Italic">Neurospora crassa</Emphasis>

 During the isolation of mutations in the heat-inducible hsp70-1 gene of Neurospora crassa by RIP (repeat-induced point mutations), several transformants were generated by electroporation of conidia with a plasmid harboring an incomplete copy of this gene. One isolate, designated E-45, containing ectopically integrated hsp70-1 DNA, exhibited a slow growth rate, low-temperature sensitivity, constitutive thermotolerance (without prior heat shock), and high constitutive peroxidase activity. The constitutive form of peroxidase (CP) was distinguishable from the heat-inducible form (HIP) by immunoinactivation employing polyclonal antiserum against the latter enzyme and by electrophoretic resolution in nondenaturing polyacrylamide gels. This enzyme was purified to near homogeneity and some of its properties examined. The relative molecular mass of native CP was in the range of 118–136 kDa, as estimated by gel filtration analysis on size exclusion matrices, whereas SDS-PAGE analysis yielded a size of ∼37 kDa for the polypeptide. Substrate saturation kinetics studies were conducted using ABTS [2,2′-azino-bis (3-ethylbenzthiazole-6-sulfonic acid)] and H₂O₂ as substrates: K _m, V _max, and K _cat values for H₂O₂ were ∼22 μM, ∼447 nmol mg⁻¹, and 0.33 s⁻¹, respectively, and those for ABTS were ∼55 μM, ∼453 nmol mg⁻¹, and 0.3 s⁻¹, respectively. Guaiacol was not used as a substrate by this enzyme. CP peroxidase was shown to be a heme-containing enzyme, stable at temperatures up to 58°C. Received: August 5, 2002 / Accepted: January 22, 2003 Acknowledgments This work was supported by an operating grant from the Natural Sciences and Engineering Research Council (NSERC) of Canada (to M.K.). The financial support provided to A. M. in the form of a graduate studentship award by the AHFMR (Alberta Heritage Foundation for Medical Research) and of a graduate teaching assistantship to A. S. by the Department of Biological Sciences, University of Calgary, is gratefully acknowledged. Correspondence to:M. Kapoor     

Peptides with anticancer use or potential

Summary.  This review is an attempt to illustrate the diversity of peptides reported for a potential or an established use in cancer therapy. With 612 references, this work aims at covering the patents and publications up to year 2000 with many inroads in years 2001–2002. The peptides are classed according to four categories of effective (or plausible) biological mechanisms of action: receptor-interacting compounds; inhibitors of protein-protein interaction; enzymes inhibitors; nucleic acid-interacting compounds. The fifth group is made of the peptides for which no mechanism of action has been found yet. Incidentally this work provides an overview of many of the modern targets of anticancer research. Received March 3, 2002 Accepted October 3, 2002 Published online January 20, 2003 Author's address: Dr. Yves Louis Janin, UMR 176 CNRS-Institut Curie, 26 rue d'Ulm, F-75248 Paris cedex 05, France, E-mail: yves.janin@curie.u-psud.fr     

Early molecular events in the development of the diabetic cardiomyopathy

Summary.  Oxidative damage to DNA has been well documented in cardiac cells isolated from diabetic patients and rats with streptozotocin-induced diabetes mellitus (DM). This study evaluates possible molecular mechanisms for early events in the development of DM-induced cardiomyopathy. Methods: To analyze the mechanism of overexpression of p21^WAF1/CIP1 and inhibition of cyclin D₁ expression in cardiomyocytes of diabetic rats we examined the methylation status of these genes by MS-PCR and assessed the possibility of epigenetic control of their expression. Results: We found that the steady-state expression of both genes is influenced by their methylation status, as an epigenetic event, of their 5′-flanking regions upon development of diabetes. Conclusions: Oxidative damage contributes to the development of cardiomyopathy via p53-dependent activation of cardiac cell death. This pathway includes de novo methylation of the P53-inducible p21^WAF1/CIP1-gene encoding a protein which binds to and inhibits a broad range of cyclin-cyclin-dependent kinase complexes. Received June 29, 2001 Accepted August 6, 2001 Published online August 9, 2002     

Dietary taurine enhances cholesterol degradation and reduces serum and liver cholesterol concentrations in rats fed a high-cholesterol diet

Summary.  The effect of taurine on hypercholesterolemia induced by feeding a high-cholesterol (HC) diet (10 g/kg) to rats was examined. When taurine was supplemented to HC for 2 wk, serum total cholesterol significantly decreased and serum HDL-cholesterol increased compared with the HC diet group. In the hypercholesterolemic rats fed the HC diet, the excretion of fecal bile acids and hepatic cholesterol 7α-hydroxylase (CYP7A1) activity and its mRNA level increased significantly, and the supplementation of taurine further enhanced these indexes, indicating an increase in cholesterol degradation. Agarose gel electrophoresis revealed that, in hypercholesterolemic rats fed the HC diet, the serum level of the heavier VLDL increased significantly, but taurine repressed this increase and normalized this pattern. Significant correlations were observed between the time-dependent increase of CYP7A1 gene expression and the decrease of blood cholesterol concentration in rats fed the HC diet supplemented with taurine. These results suggest that the hypocholesterolemic effects of taurine observed in the hypocholesterolemic rats fed the HC diet were mainly due to the enhancement of cholesterol degradation and the excretion of bile acid. Received December 4, 2001 Accepted January 2, 2002 Published online September 10, 2002 Acknowledgment This work was supported by a grant of Taisho Pharmaceutical Co., Ltd (Japan). We thank J. I. Gordon for their generous gifts of cDNAs. Authors' address: Dr. Hidehiko Yokogoshi, School of Food and Nutritional Sciences, The University of Shizuoka, Shizuoka 4228526, Japan, E-mail: yokogosi@u-shizuoka-ken.ac.jp     

Words in DNA sequences: some case studies based on their frequency statistics

 One of the critical requirements of data analysis involving large DNA sequences is an effective statistical summarization of those sequences. In this article DNA sequences have been analyzed based on word frequencies. Our analysis focuses on the detection of structural signature of a genome reflected in word frequencies and identification of phylogenetic relationships among different species reflected in the variation of word distributions in their DNA sequences. We have carried out a statistical study of the complete genome of baker's yeast, of various ribosomal RNA sequences from different prokaryotic and eukaryotic organisms and of the full genomes of some bacteriophages. Our exploratory analysis amply demonstrates the usefulness of DNA word frequencies in reducing the dimensionality of large sequences while retaining some of the structural information there that can have biological significance. Some conceptual issues that arise in course of our investigation have been addressed. A few interesting problems related to the statistics of DNA words have been pointed out with some indication of their possible solutions. The work has been partially motivated by the fact that sequence alignment and homology techniques that are quite popular for comparing and analyzing relatively smaller DNA sequences of nearly equal sizes are not applicable to data consisting of large sequences with widely varying sizes, which may contain segments with unknown or no biological functions, and consequently their comparison through functional homology is either impossible or extremely difficult. Received: 15 October 2000 / Revised version: 8 October 2002 Published online: 28 February 2003 Current address: CF186, Salt lake, Calcutta 700064, India Research presented here was supported in part by a grant from Indian Statistical Institute. Key words or phrases: Average linkage clustering – Chernoff's faces – Dendrograms – DNA words – F-ranks of words – F-ratios of words – l ₁-distance – Phylogenetic relationships – Rank correlation – Single linkage clustering     

Scleroderma laeve (Gasteromycetes, Sclerodermatales), new to Japan

 A Scleroderma species collected on sandy soil under trees of Lithocarpus edulis in Saitama Prefecture, central Japan, is identified as Scleroderma laeve, a new record for Japan. Macroscopic and microscopic features are given. Received: May 24, 2002 / Accepted: September 9, 2002 Acknowledgments We thank Ms. Ryoko Onuma, who offered some useful literature on Scleroderma. We are also grateful to Dr. Toshimitsu Fukiharu (Natural History Museum and Institute, Chiba) for his help with preserving the specimens. For collecting specimens, we are grateful to Ms. Ayano Kimura, Mr. Tomoya Matsuyama, and Mr. Takahiro Uchida. Correspondence to:T. Kasuya     

Synthesis and transformations of a pyrazole containing <Emphasis Type="Italic">α</Emphasis>,<Emphasis Type="Italic">β</Emphasis>-didehydro-<Emphasis Type="Italic">α</Emphasis>-amino acid derivatives

Summary.  2H-Pyran-2-ones 1 were transformed with various hydrazines into (E)- or (Z)-α,β-didehydro-α-amino acid (DDAA) derivatives 4 (and 7) containing a highly substituted pyrazolyl moiety attached at the β-position. With heterocyclic hydrazines, the products 4 were accompanied also by decarboxylated enamines E-6. In order to separate (E/Z)-mixtures of acids, they were transformed to the corresponding methyl esters 9 and 10 by the application of diazomethane. Catalytic hydrogenation under high pressures with Pd/C as a catalyst resulted in the formation of racemic alanine derivatives 11. Received January 29, 2002 Accepted May 27, 2002 Published online December 18, 2002 RID="*" ID="*"  Dedicated with deep respect to Professor Waldemar Adam on the occasion of his 65^th birthday. Acknowledgements We thank the Ministry of Education, Science and Sport of the Republic of Slovenia for the financial support (P0-0503-103). Dr. B. Kralj and Dr. D. Žigon (Center for Mass Spectroscopy, “Jožef Stefan” Institute, Ljubljana, Slovenia) are gratefully acknowledged for the mass measurements. Authors' address: Prof. Marijan Kočevar, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Aškerčeva 5, SI-1000 Ljubljana, Slovenia, E-mail: marijan.kocevar@uni-lj.si