Conditions for the formation of cyclic compounds between pyridoxal phosphate and 5-hydroxytryptamine or 5-hydroxytryptophan

5-Hydroxytryptamine (5HT) and 5-hydroxytryptophan (5HTP) form cyclic compounds (probably of the tetrahydro--carboline type) with pyridoxal phosphate (PLP). In the first step of reaction a Schiff's base is formed; during incubation it is transformed into a cyclic compound with a maximum absorption spectrum at 330 nm. The degree of cyclization depends on pH and substrate concentrations. One mole of 5HT or 5HTP reacts with one mole of coenzyme. The velocity of cyclization increased with an excess of either 5HT (5HTP) or PLP, without any change in the mole to mole ratio. The formation of cyclic compounds was confirmed by the use of isotopes, separation from substrates being achieved by high-voltage electrophoresis.     

Phosphopyridoxal complexes with histamine and histidine (1) the kinetics of complex formation between pyridoxal 5′-phosphate and histamine

Amines and amino acids are able to form cyclic compounds with pyridoxal 5′-phosphate (PLP). The quantitative relationship between histamine and PLP in the cyclization reaction were examined. It was found that one mole of amine reacts with one mole of coenzyme. The velocity of complex formation increased with an excess of either histamine or PLP, without any change in molar ratios. The formation of cyclic compound was confirmed by the use of isotopic method. The separation of cyclic compound from histamine, but not from PLP, was achieved by paper chromatography.     

Synthesis of 1,3,6,8-tetraphenyloctane as a tetramer model for polystyrene

The styrene tetramer, 1,3,6,8-tetraphenyloctane ( 5 ), was prepared by addition of styrene and phenethyl bromide ( 4 ) in a 1:1 mole ratio to a stirred suspension of lithium in tetrahydrofuran. The reaction was found to proceed via 1,4-diphenyl-1,4-butanediyldilithium ( 3 ), which reacts “in situ” with the alkyl halide 4 to give the tetramer 5 . Mass and NMR spectra were found to be in agreement with the proposed structures.     

Histochemical studies on the distribution of hexokinase and several enzymes related to catecholamine production in the locus coeruleus of the squirrel monkey.

Protein sulfhydryl groups are histochemically demonstrated by reacting with DDD followed by coupling with Fast blue B. The molar absorptivity of the formed azo dye is 19000 per mole SH reacted. DDD simultaneously reacts with protein-SH- and -SS-groups. However, the reaction with SH-groups is approximately 1000 times faster than that observed with SS-groups. With Ehrlich ascites tumour cells the reaction of DDD with SH-groups is completed within 7 h while the reaction of DDD with SS-groups needs 14 days for completion. Due to the extreme difference in the reaction rates protein bound SH-groups as well as reactive SS-groups can be estimated quantitatively by cytospectrophotometrical methods. The cells investigated showed an average SH-content of (1,30 +/- 0,03) X 10(-14) M SH/cell while the average content of reactive SS-groups was (1,59 +/- 0,28) X 10(-14) M SS/cell. In addition it was found that especially the amount of reactive SS-groups per cell is not constant but exhibits seasonal variations.     

Ultraviolet spectrophotometric studies of the reactivity of a water-soluble polymer containing pendant 8-hydroxyquinoline moieties with metal ions

The water-soluble polymer 4 containing pendant 8-hydroxyquinoline (oxine) moieties was prepared and its reactivity with metal ions was studied by means of ultraviolet (UV) spectrophotometry. Polymer 4 was found to form complexes with metal ions in a mole ratio of 2 : 1 (oxine : metal), which is also obtained for the metal complexes of model compound 3 except for the Mg²⁺ complex. Polymer 4 hardly reacts with Mg²⁺, while model compound 3 forms a 1 : 1 mol/mol complex. The stability of the complexes of polymer 4 with metal ions was found to decrease in the following order: Cu²⁺ > Ni²⁺ > Zn²⁺ > Cd²⁺ > Hg²⁺ > Mg²⁺.     

Polymerization of methyl methacrylate in the presence of the system ethylaluminium dichloride—p-chloranil

The polymerization of methyl methacrylate ( 5 ) in the presence of the system ethylaluminium dichloride ( 2 )—p-chloranil ( 1 ) was found to proceed much easier than in the presence of only 2 . The polymerization is initiated by ethyl radicals resulting from the reaction of 2 with 1 . The effects of mole ratio of reactants, temperature, and reaction time on the polymerization yield and intrinsic viscosity of the polymer was studied and the results are discussed.     

Acceleration effect of acids on the co-dimer formation from 1-(4-chlorophenyl)ethyl esters and styrene

A linear unsaturated co-dimer of styrene and p-chlorostyrene, 1-phenyl-3-(4-chlorophenyl)-1-butene ( 2 ), was preferentially produced by reaction of 1-(4-chlorophenyl)ethyl diphenyl phosphate ( 1 ) with styrene. The reaction was found to be extraordinarily accelerated by addition of trifluoromethanesulfonic acid. 1-(4-chlorophenyl)ethyl acetate reacts readily with styrene in the presence of trifluoromethanesulfonic acid to afford 2 in good yields, whereas the acetate is inert toward styrene in the absence of a super acid.     

Preparation and characterization of bisphenol A-cationized bovine serum albumin

To detect BPA residue in the environment quickly by immune method, preparation of high quality antibody against BPA was the most critical step of project. Based on Mannich-type reaction and EDC method, we produced BPA-cBSA and BHPVA-BSA against BPA and the conjugates were characterized by UV-Vis and FT-IR spectroscopy. Compared with BSA, cBSA as carrier protein could improve the efficiency of coupling and significantly enhance the immune response against BPA. The mole coupling ratio of BPA-cBSA (8:1) was greater than that of BHPVA-BSA (5:1). We also observed that the similar sensitivity of antisera against BPA between the BPA-cBSA group and BHPVA-BSA group.     

Mechanism of the NCA polymerization 7. The primary and secondary amine-initiated polymerization of β-amino acid NCAs

The reaction of β-alanine N-carboxyanhydride (β-Ala NCA) ( 1 ) with various primary and secondary amines was investigated at room temperature. Three reaction products were found: poly(β-alanine), β-alaninamides, and N′-substituted β-ureidopropionic acids. The mole ratio of these reaction products depends on the reaction conditions, above all on the NCA/amine ratio, and on the nucleophilicity/basicity ratio of the amines. All amines with pK_a-values > 8,0, including the amino end-groups of the growing chains, cause the formation of β-isocyanatocarboxylate ions by deprotonation of the β-NCAs, and thus, the formation of β-ureidocarboxylic acids. If the chain ends are involved, this reaction sequence is a termination step, and it is this termination step which is responsible, for that high polymerization degrees (> 60) are not accessible by a primary or secondary amine-initiated polymerization of β-NCAs. The β-ureidocarboxylic acid end-groups are detectable in the ¹³C NMR spectra of the poly(β-amide)s.     

Precipitin Inhibition of Candida stellatoidea Antiserum with Oligosaccharides Obtained from the Parent Mannan

Inhibition of immune precipitation with oligosaccharides obtained from Candida stellatoidea mannan has been used to provide more information about the haptenic groups of this serologically active polysaccharide. The oligosaccharides di-, tri-, tetra-, and a mixture of penta- and hexasaccharides were studied. The inhibitory activity of these materials was tested with two immune sera. With one serum, 0.8 μmole of the mixture of penta- and hexasaccharides inhibited the reaction by 87%, and, with the other serum, 0.4 μmole of the mixture inhibited the reaction by 99%. Monosaccharides were also tested with each antiserum and found to be noninhibitory. It is apparent that the mixture of oligosaccharides containing 5 to 6 mannose units was the most effective inhibitor. Since it is known that these oligosaccharides contain a predominance of α 1-2 linkages and lesser numbers of α 1-3 linkages, it is likely that these are important in the structural configuration of the antigenic determinants.     

Darstellung einer homologen Reihe von oligoallylalkoholen mit 1-cyano-1-methylethyl-endgruppen. Beispiel einer mehrfachen matrizenreaktion und einer replicaoligomerisation

Reduction and hydrolysis of the ladder oligomers 1, 2, 3, 4 , and 5 prepared from the acrylates of oligo (hydroxyphenylene-methylene)s was found to lead to a homologous series of oligo (allylalcohol)s ( 6a, 7a, 8a, 9a and 10a ) with good yields. These alcohols were characterized by analytical and spectroscopic methods. The reaction sequences, starting with the esterification of the oligo[(hydroxyphenylene) methylene]s 11a – 11e with acryloyl chloride followed by the formation of the ladder oligomers and ending with their reduction and hydrolysis into the oligo(allyl alcohol)s and the starting compounds 11a – 11e , represent a simple matrix reaction. A mixture of multiple acrylates was also subjected to the same reaction sequences, resulting in a multiple matrix reaction. A mixture of matrix compounds 11b – 11e with a known mole ratio was esterified with acryloyl chloride, then transformed into a mixture of ladder oligomers and subsequently reduced and hydrolyzed to afford a mixture of oligo(allyl alcohol)s with the same mole ratio of the starting matrices as shown by gas chromatographic analysis. This represents a paradigm for a replica oligomerisation.     

Ion (H+, Ca2+, Co2+) and temperature effects on a hyperpolarization-activated membrane current in the lobster stretch receptor neurone

The effects of some ions (H+, Ca2+, Co2+) and temperature on the Q-channel (a channel which conducts a hyperpolarization-activated membrane current, IQ) was investigated in the slowly adapting lobster stretch receptor neurone. It was found: (1) that increases in pH cause an increase in the maximum channel conductance; (2) that Co2+ (1 mM) and increases in extracellular Ca2+ produce a positive shift of the relationship between the membrane voltage and the steady-state channel activation along the voltage scale; (3) that Co2+ and decreases in extracellular pH cause a decrease in rate of the voltage-dependent step of the channel's gating reaction; (4) that none of the ions has an effect on the rate of the voltage-independent step of the gating reaction; and (5) that Co2+ and K+ do not interfere with each other's actions on the channel's gating reaction and maximum ion conductivity. Increases in temperature from 13 to 23 degrees C were found: (1) to cause an increase in the maximum Q-channel conductance by a factor of 1.7; (2) to have no effect on the voltage dependence of the channel's gating reaction; but (3) to lead to an increase in rate of the gating reaction by a factor of about five for the voltage-dependent, and by a factor of about three for the voltage-independent gating step. The temperature sensitivity of the IQ mechanism proved to be mathematically reproducible by a previously developed, and slightly modified Q-channel model (Edman et al. 1987, Edman & Grampp 1989), and to be of no significance in the control of membrane excitability in a thermally unstable environment.     

Copolymerization of carbon dioxide with propylene oxide in the presence of catalysts based on alkylmetal compounds and pyrogallol

Carbon dioxide was copolymerized with propylene oxide (PO, 2-methyloxirane) in the presence of a catalyst system based on alkylmetal compounds (MtR_n, Mt = Zn, Cd, Al) and pyrogallol (PG) at mole ratios 1:1, 2:1, and 3:1, respectively. The reaction was found to produce an alternating copolymer poly(propylene carbonate), [poly(oxycarbonyloxypropylene)], using Zn and Cd containing catalysts and non-alternating copolymers with Al containing catalysts. For the system ZnR₂/PG (mole ratio 2 : 1), the most active system, the influence of substituents R at the zinc atom, as well as effects of solvents and complexing agents on the copolymer yield and intrinsic viscosity were investigated. The results are discussed in terms of an anionic coordinative copolymerization mechanism.     

Polymere brenzcatechin-derivate, 2. Über die alternierende copolymerisation von 4-propenylbrenzcatechin-derivaten mit maleinsäureanhydrid durch tributylboran

The copolymerization of maleic anhydride (MAn) with 4-propenylpyrocatechol derivatives (e.g., eugenol ( 1 ), isoeugenol ( 2 ), safrol ( 3 ), and isosafrol ( 4 )), initiated by tributylborane, was investigated in cyclohexanone at 30°C in the presence of oxygen. It was found that 1:1 copolymers are formed, independent of the comonomers and of mole ratios in the feed, whereas under nitrogen neither 1 nor 3 copolymerized with MAn, as already reported. MAn was found to react with the isopropenyl compounds (and styrene derivatives) 2 and 4 nearly 10² times faster than with the corresponding allyl compounds 1 and 3 . Therefore, not only oxygen but also the structure of side chains seems to play an important rôle in these copolymerisation systems. The reaction mechanism is discussed. It is interesting to note that the 1:l-copolymers which were obtained from MAn and 2 or from MAn and 4 are remarkably thermally stable. These copolymers decomposed endothermally at temperatures > 300°C.     

Step growth polymerization via tandem ene and diels-alder reactions

In contrast to other electron deficient enophiles or dienophiles which react with 1,4-cyclohexadiene (1,4-CHD) under aromatization, 1,2,4-triazoline-3,5-diones react in a defined reaction sequence. In a first step the 1,4-cyclohexadiene reacts via an ene-reaction. The intermediately formed substituted 1,3-cyclohexadiene immediately reacts in a Diels-Alder reaction. The regiochemistry of the Diels-Alder reaction is controlled by the solvent polarity. This reaction sequence can be used to synthesize polymers. Low-molarmass model compounds were synthesized to elucidate the stereochemistry of the polymers. By varying the bistriazolinedione, polymers with backbones of different rigidity are available.     

Le phényl-1 éthylpotassium,amorceur de polymérisation anionique: Préparation par clivage de l'oxyde de bis(phényl-1 éthyle); étude du milieu réactionnel

1-Phenylethylpotassium ( 5 ), an efficient anionic polymerization initiator in tetrahydrofuran (THF) solution serving as a substitute for 1-methyl-1-phenylethylpotassium in most of its applications, was obtained by cleavage of bis(1-phenylethyl) ether ( 1 ) with potassium. Ether cleavage reactions were carried out in THF at mole ratios potassium/ 1 = 2/1 and 1/1, and the resulting solutions were submitted to careful analysis. All by-products formed in the reaction media were unambiguously identified and their mole fractions in the resulting mixture determined. The presence of these by-products was found not to influence the initiator efficiency.     

Über einige Copolyurethane ausgehend von Piperazin

Bis(2-hydroxyethyl) piperazine-1,4-dicarboxylate ( 3 ) was prepared by addition of ethylene carbonate to piperazine (mole ratio 2:1). The reaction of 3 with aliphatic or aromatic dicarboxylic acid chlorides yielded alternating polyesterurethanes 5 and 7 . The sequenced copolyurethane 8 was obtained by polyaddition of 3 and 4,4′-methylene bis(phenylisocyanate). Interfacial polycondensation of the bis(chloroformyl) derivative of 3 with aliphatic and aromatic diamines afforded ordered copolyurethanes of type 11 .     

Synthesis of new monomers by addition reactions of diethylamine to 1,4-divinylbenzene catalyzed by lithium diethylamide

Addition reactions of diethylamine onto 1,4-divinylbenzene (DVB) catalyzed by lithium diethylamide were examined to find a synthetic route to a group of new monomers possessing dialkylamino substituents, which is expected to be a starting material for biomedical polymers such as ionic polymer complexes, polycations, and others. It was found that 1-(2-diethylaminoethyl)-4-vinylbenzene ( 1 ) and 1,4-bis(2-diethylaminoethyl)-benzene ( 2 ) can be prepared selectively, because the rate of the first step of the addition reaction was twenty times as large as that of the second step. Results of kinetic studies on the addition reactions towards DVB are discussed with the aid of ¹³C NMR data and compared with other p-vinylbenzene derivatives.     

Polymerization of N-CARBOXY-α-amino acid anhydride by organometallic compounds III. Mechanism of asymmetric selective polymerization of n-carboxy alanine anhydride by organoaluminum catalysts

Copolymerizations of D - and L -N carboxy alanine anhydride by Al(C₂H₅)₃ and (i-C₄H₉)₂AlN(C₂H₅)₂ were studied in order to elucidate the mechanism of stereospecific polymerization of the N-carboxy-α-amino acid anhydride (NCA) with the two organoaluminum compounds. The enantiomer involved in higher concentration in the starting monomers was polymerized preferentially in the propagation step by these catalysts. The mechanism of the asymmetric selective polymerization was concluded to be the growing chain end control, neither the enantiomorphic catalyst sites control nor the control by the helical conformation of the growing polymer chains. It was found in Al(C₂H₅)₃ initiated polymerization system that almost perfect stereoselective reaction took place at an early stage of the polymerization; that is, about five mole of the NCA initially reacted with one mole of Al(C₂H₅)₃ and the amounts of L - and D -enantiomer of the NCA reacted were always equal independently of enantiomer ratio in the starting NCA.     

Copolymerization of 1-vinylindol with maleic anhydride

The formation of a charge-transfer complex between 1-vinylindole ( 1a ) and maleic anhydride (MA) was detected by ¹H NMR analysis, and the corresponding K_eq was measured (K_eq=0,251 mol in CDCl₃ at 25°C). It could be shown that this complex can be involved both in the initiation and propagation steps of the 1a -MA copolymerization by carrying out spontaneous copolymerization experiments and studying the influence of the feed composition on the conversion and [η] of the copolymer. The structure of the 1a -MA copolymer, investigated by ¹³C NMR spectroscopy, was found to be complicated due to the formation of indoline rings along the chains by an attack of the propagating MA radical at position 2 in the indole ring. As a consequence an excess of MA, with respect to a 1:1 mole ratio of monomer feed, was usually found in the copolymer. The mechanism of the cyclization reaction was clarified by copolymerizing MA with 2-methyl-1-vinylindole ( 1b ), 3-methyl-1-vinylindole ( 1c ), or 2,3-dimethyl-1-vinylindole ( 1d ). An alternating copolymer with MA (mole ratio 1:1 of monomeric units), without irregularities, was obtained only by employing 1d as a comonomer.