Modification of hyaluronic acid with aromatic amino acids

Hyaluronic acid was modified with aromatic amino acids (5-aminosalicylic, 4-aminosalicylic, anthranilic, and p-aminobenzoic) in the presence of 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide. The modified glycans contained 9-43% of arylamide groups and 10-33% of isoureidocarbonyl groups depending on the nature of the amino acid. Reduction with sodium borohydride allowed the conversion of isoureidocarbonyl groups into hydroxymethyl groups.     

Taurine transport systems in the ciliate protozoanTetrahymena pyriformis

Summary Tetrahymena pyriformis cultivated in the presence of 1 mM taurine prior to transfer of the cells to non-nutrient medium express an enhanced capacity for concentrative taurine uptake and for taurine diffusion compared to cells grown without added taurine. The unidirectional taurine influx in taurine-grown cells comprises a saturable component with K_m -257M, V_max = 21 n-moles · g dry wt^–1 sd min^–1, and a diffusion component with a diffusion constant of 0.20 ml · g dry wt^–1 · min^–1. At extracellular taurine concentrations <30M, 20% of the influx is via the saturable system and 80% is via the diffusion system. 19% of the influx in Na⁺-dependent, Cl^–-independent, and not inhibitable with structural analogues to taurine, suggesting that the transport system responsible for the saturable component in Tetrahymena is different from the Na⁺- and Cl^–-dependent taurine translocating system (the-system) described in vertebrate cells. The unidirectional taurine influx is reduced by 80% by 1mM DIDS (inhibitor of anion exchange and anion channels) and by 1 mM MK196 (indachrinone, inhibitor of anion channels) indicating that taurine diffusion inTetrahymena is via a channel, which is permanently active and which resembles the swelling-induced taurine channel seen in mammalian cells. Taurine influx is stimulated by the forskolin analogue 1,9-dideoxyforskolin and by arachidonic acid, and this stimulation is in both cases sensitive to DIDS and MK196.Abbreviations DDF dideoxyforskolin - DIDS 4,4-diisothiocyano-2,2-stilbene disulfonic acid - GABA gamma amino butyric acid - HEPES N(2-hydroxyethyl)piperazine-N-(2-ethane sulfonic acid) - MK196 indachrinone - MOPS 3-(N-morpholino)propane sulfonic acid - NMDG n-methyl-dglucamonium - OPA ortho-phtalaldehyde - PCA perchloric acid - TES N-tris(hydroxy methyl)-methyl-2-amino ethane sulfonic acid - TRIS tris(hydroxy methyl)amino methane     

DNA binding domains in Tn3 transposase

Summary Various segments of Tn3 transposase were fused individually to -galactosidase, and the resulting fusion proteins were examined for their DNA binding ability by a nitrocellulose filter binding assay. Analyses of a series of the fusion proteins revealed that the N-terminal segment of the transposase (amino acid positions 1–242; the transposase gene encodes 1004 residues in all) had specific DNA binding ability for the 38 bp terminal inverted repeat (IR) sequence, and the central segment (amino acid positions 243–632) had non-specific DNA binding ability. Further analyses of each of the two regions revealed that the N-terminal segment could be divided into at least two subsegments (amino acid positions 1–86 and 87–242), neither of which had specific DNA binding ability, but which both possessed nonspecific DNA binding ability. The central segment included two subsegments (amino acid positions 243–289 and 439–505) with non-specific DNA binding ability. These results and other observations suggest that Tn3 transposase has several domains including those responsible for non-specific DNA binding, and a combination of two or more domains gives rise to specific DNA binding activity. The C-terminal segment of the transposase (amino acid positions 633-1004), which is very well conserved among transposases encoded by Tn3 family transposons, had no DNA binding ability. This segment may represent the main part of the catalytic domain responsible for the initiation step of transposition.     

Chemical modification of heparin

Heparin was modified at carboxyl groups by reaction with several pharmacologically important amino-containing compounds in aqueous medium in the presence of 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide. In dependence on the nature of the amine and the ratio of reagents, conjugates containing 36–100% amide and 0–25% isoureidocarbonyl groups were synthesized. Isoureidoarylamide groups are present, along with amide moieties, in the products of heparin modification by hydroxyl-containing aromatic amines. The conjugate of heparin with p-aminobenzoic acid contained oligomeric arylamide.     

In vitro propagation of the bamboo (Bambusa tulda Roxb.) through shoot proliferation

An efficient protocol has been developed for the in vitro propagation of Bambusa tulda through shoot proliferation. Shoots from 3-week-old aseptically grown seedlings were used to initiate cultures. Multiple shoots were obtained on liquid Murashige and Skoog (MS) medium supplemented with 6-benzylaminopurine (8×10^–6M) and kinetin (4×10^–6M). Continuous shoot proliferation at a rate of 4–5 fold every three weeks was achieved through forced axillary branching. More than 90% of the shoots could be rooted on a modified MS medium containing indoleacetic acid (1×10^–5M) and coumarin (6.8×10^–5M). Following simple hardening procedures, the in vitro raised plants were transferred to the soil with more than 80% success.Abbreviations BAP 6-benzylaminopurine - 2-ip 6-,-dimethylallylaminopurine - Kn kinetin - IAA 3-indoleacetic acid - IBA 3-indolebutyric acid - NAA 1-naphthaleneacetic acid     

Activation of Peroxidase-Catalyzed Oxidation of Aromatic Amines with 2-Aminothiazole and Melamine

The peroxidase-catalyzed oxidation of 3,3",5,5"-tetramethylbenzidine (TMB), ortho-phenylenediamine (PDA), and 5-aminosalicylic acid (5-ASA) is significantly accelerated in the presence of 2-aminothiazole (AT) and melamine (MA), and an increase in their concentrations is associated with a parallel increase in the k _cat and K _m values for TMB and PDA. The activation of the peroxidase-catalyzed oxidation of TMB and PDA is quantitatively characterized by a coefficient (degree) (M^–1) which significantly depends on pH in the range 6.2-6.4, 6.4-7.4, and 6.0-7.4 for the TMB–AT, TMB–MA, and PDA–MA pairs, respectively. An increase in the coefficient with increase in pH confirms nucleophilicity of activation of the peroxidase-catalyzed oxidation of the aromatic amines in the presence of AT and MA. Under optimal conditions the coefficients for the TMB–AT, PDA–AT, TMB–MA, and PDA–MA pairs vary in the limits of (1.90-3.53)·10³ M^–1.     

Identification of Mu-Class Glutathione Transferases M2-2 and M3-3 as Cytosolic Prostaglandin E Synthases in the Human Brain

Cytosolic prostaglandin (PG) E synthase was purified from human brain cortex. The N-terminal amino acid sequence, PMTLGYXNIRGL, was identical to that of the human mu-class glutathione transferase (GST) M2 subunit. Complementary DNAs for human GSTM2, GSTM3, and GSTM4 subunits were cloned, and recombinant proteins were expressed as homodimers in Escherichia coli. The recombinant GSTM2-2 and 3-3 catalyzed the conversion of PGH₂ to PGE₂ at the rates of 282 and 923 nmol/min/mg of protein, respectively, at the optimal pH of 8, whereas GSTM4-4 was inactive; although all three enzymes showed GST activity. The PGE synthase activity depended on thiols, such as glutathione, dithiothreitol, 2-mercaptoethanol, or L-cysteine. Michaelis-Menten constants and turnover numbers for PGH₂ were 141 M and 10.8 min^–1 for GSTM2-2 and 1.5 mM and 130 min^–1 for GSTM3-3, respectively. GSTM2-2 and 3-3 may play crucial roles in temperature regulation, nociception, and sleep-wake regulation by producing PGE₂ in the brain.     

Permeability of membranes to amino acids and modified amino acids: Mechanisms involved in translocation

Summary The amino acid permeability of membranes is of interest because they are one of the key solutes involved in cell function. Membrane permeability coefficients (P) for amino acid classes, including neutral, polar, hydrophobic, and charged species, have been measured and compared using a variety of techniques. Decreasing lipid chain length increased permeability slightly (5-fold), while variations in pH had only minor effects on the permeability coefficients of the amino acids tested in liposomes. Increasing the membrane surface charge increased the permeability of amino acids of the opposite charge, while increasing the cholesterol content decreased membrane permeability. The permeability coefficients for most amino acids tested were surprisingly similar to those previously measured for monovalent cations such as sodium and potassium (approximately 10^–12–10^–13 cm · s^–1). This observation suggests that the permeation rates for the neutral, polar and charged amino acids are controlled by bilayer fluctuations and transient defects, rather than partition coefficients and Born energy barriers. Hydrophobic amino acids were 10² more permeable than the hydrophilic forms, reflecting their increased partition coefficient values.External pH had dramatic effects on the permeation rates for the modified amino acid lysine methyl ester in response to transmembrane pH gradients. It was established that lysine methyl ester and other modified short peptides permeate rapidly (P = 10^–2 cm · s^–1) as neutral (deprotonated) molecules. It was also shown that charge distributions dramatically alter permeation rates for modified di-peptides. These results may relate to the movement of peptides through membranes during protein translocation and to the origin of cellular membrane transport on the early Earth.Abbreviations DCP dicetylphosphate - DMPC dimyristoyl phosphatidylcholine - EPC egg phosphatidylcholine - LUV large unilamellar vesicle - MLV multilamellar vesicle - PLM planar lipid membrane - SUV small unilamellar vesicle - pH transmembrane pH gradient     

Growth of Albugo candida (race unidentified) on Brassica juncea callus cultures

An obligate fungus Albugo candida (Pers. ex Lév.) Ktze. (race unidentified) was successfully grown on host callus tissues of Brassica juncea cv. Varuna. Of the various type of diseased explants used, young (green) hypertrophied inflorescence axis bearing non-erumpent zoosporangial blisters allowed the fungus to multiply asexually over the host calli on modified MS-medium (Murashige and Skoog, 1962). The dual cultures were maintained up to 6–8 subcultures without loss of viability of zoosporangia on MS-medium supplemented with 10.0 mg L^–1 IBA, 0.05 mg L^–1 kinetin, 25.0 mg L^–1 AA, 1.0 mg L^–1 biotin, 1.0 mg L^–1 thiamine-HCl and 1.0 g L^–1 casein hydrolysate. The fungus grew only on the callus cells and not axenically on the medium. Pathogenicity test and histopathology of cultures proved the existence of the viable fungus in vitro.Abbreviations AA ascorbic acid - BAP 6-benzyl aminopurine - CH casein hydrolysate acid hydrolysed - 2,4-D-2,4 dichlorophenoxy acetic acid - FAA formaldehyde acetic acid - IAA indole-3-acetic acid - IBA indole-3-butyric acid - HgCl₂ mercuric chloride - Kinetin 6-furfuryl aminopurine - MS Murashige and Skoog (1962) - NAA alpha naphthalene acetic acid - rh relative humidity - sdw sterile distilled water - wt. weights     

Changes in amino acid content of an algal feed species (Navicula sp.) and their effect on growth and survival of juvenile abalone (Haliotis rubra)

The growth and survival of juvenile Haliotis rubra, when fed with the diatom Navicula sp. cultured in f/2 medium containing combined nitrogen at 24.71 mg NO₃-N L^–1 (high), 12.35 mg NO₃-N L^–1 (standard) or 2.47 mg NO₃-N L^–1 (low), were compared in a 33-day trial. The alga in the low nitrogen medium contained 37% less total amino acid than that in the high and standard nitrogen media. There was a slightly greater reduction in essential amino acids (40%) compared to non-essential amino acids (35%). Juvenile abalone feeding on Navicula grown in medium with low nitrate and lower total amino acid content grew more slowly than when fed on the same species grown in standard or higher nitrogen medium with a higher amino acid content. The growth rate of juveniles was highest (43 m d^–1) in the high nitrate treatment followed (40 m d^–1) by the standard nitrate treatment and lowest (31 m d^–1) in the low nitrate treatment. The survival of the juveniles was also effected by the diet. Survival was better in the high and standard nitrogen media (88%) than the low nitrogen medium (75%). The results suggest that in order to achieve uniformity in nutritional quality of diatoms and good growth of abalone juveniles in commercial abalone nurseries, the nitrogen concentration in tanks should be monitored and additional nitrate added to provide an optimum concentration of between 2 and 12 mg NO₃-N L^–1.     

Studies of protoplast culture types and plant regeneration from callusderived protoplasts of Asparagus officinalis L. cv. Lucullus 234

Plating efficiency and colony formation of callus-derived protoplasts of Asparagus officinalis L. cv. Lucullus 234 differed significantly with different protoplast culture media and types of culture. Osmotic conditions and hormone concentrations of liquid media produced the greatest influence on plating efficiency and colony formation in bead culture. Protoplasts grew best in bead culture with a solid modified Kao & Michayluk protoplast culture medium (KM) supplemented with 0.5 mg l^–1 -naphthaleneacetic acid (NAA), 0.5 mg l^–1 2,4-dichlorophenoxyacetic acid (2,4-D), 0.5 mg l^–1 kinetin, and 0.6% agarose (KM6) and a liquid modified KM medium differing from KM6 medium in sugar content, having 0.18 M sucrose and 0.18 M mannitol (A8). An average plating efficiency of 19.1% and colony formation of 15.5% was obtained one week after isolation in bead culture with the KM6 and A8 media. The highest average shoot regeneration of 92.3% was obtained with a Murashige & Skoog medium (MS) containing 0.125 mg l^–1 NAA, 0.125 mg l^–1 2,4-D, 0.25 mg l^–1 6-benzylaminopurine (6-BAP) and 3% sucrose. Plants have been regenerated and transferred to the greenhouse.Abbreviations NAA -naphthaleneacetic acid - 2,4-D 2,4-dichlorophenoxyacetic acid - 6-BAP 6-benzylaminopurine     

(2S)-2-Amino-5-chloro-4-hydroxy-5-hexenoic acid,a new chloroamino acid,and related compounds fromAmanita gymnopus

Combining different chromatography systems, unusual nonprotein amino acids were isolated and unequivocally identified from a small amount (less than 100 g fresh weight) ofAmanita gymnopus fruit body. Without obtaining crystals of these amino acids, on the basis of¹H-NMR determination, high resolution mass spectrometry, chlorine analysis and oxidation with L-amino acid oxidase, one of them proved to be a new chloroamino acid, (2S)-2-amino-5-chloro-4-hydroxy-5-hexenoic acid (G2). The other three were (2S)-2-amino-5-hexenoic acid (G1), (2S)-2-amino-4,5-hexadienoic acid (G3) and (2S)-2-amino-5-hexynoic acid (G4). Amino acid (G1) was also encountered for the first time in natural products. Amino acid (G3) has been reported from several kinds of fungi belonging toAmanita, subgenusLepidella. The occurrence of amino acid (G4) was already reported fromCortinarius claricolor.Part 23 in the series Biochemical studies of nitrogen compounds in fungi. Part 22, Hatanaka, S. I. et al. 1985. Trans. Mycol. Soc. Japan26: 61–68.     

Tissue culture ofKarwinskia humboldtiana—a plant producing toxins with antitumoural effects

Isolated embryos ofKarwinskia humboldtiana were cultured in vitro. The growth of embryos and development to plantlets on woody plant medium supplemented with indole-3-acetic acid 6.10^-2 mol l^–1, gibberellic acid (GA₃) 3.10^-2 mol l^–1, and 6-benzylaminopurine (BA) 2 mol l^–1 was obtained. Multiplication of shoots and rooting of excised shoots has been achieved. Callus formation on modified Murashige-Skoog medium supplemented with 1-naphthaleneacetic acid 10 mol l^–1, GA₃ 14 mol l^–1, and kinetin 5 mol l^–1 on hypocotyls, or on root cultures on medium supplemented with 2.4-dichlorophenoxyacetic acid 10 mol l^–1 and BA 10 mol l^–1 was induced.Abbreviations BA 6-benzylaminopurine - 2,4-d 2,4-dichlorophenoxyacetic acid - GA₃ gibberellic acid - IAA indole-3-acetic acid - NAA 1-naphthaleneacetic acid - TEM transmission electron microscopy     

Nucleotide sequence of the 3′-terminal region of chilli vein-banding mottle potyvirus isolated from pepper in Thailand

The sequence of the 2227 nucleotides of the 3-terminus of chilli vein-banding mottle virus-Chiangmai isolate (CVbMV-CM1) genome was determined. This sequence encodes a putative 287 amino acid coat protein. Downstream of coat protein coding region is a 288 nucleotide untranslated sequence terminated by a polyadenylate tract. The amino acid sequence of coat protein contained aspartic acid–alanine–glycine tripeptide, which may correlate with the high frequency of aphid transmissibility. The cleavage site between large nuclear inclusion protein (NIB) and coat protein was glutamine/serine. Comparison of 3 non-coding region nucleotide and coat protein amino acid sequences of CVbMV-CM1 with those of other 18 potyviruses showed 44–56% and 54–65% homology respectively, suggesting CVbMV should be regarded as new potyvirus.     

Tryptophanase in aqueous methanol: the solvent effects and a probable mechanism of the hydrophobic control of substrate specificity

To shed light on the mechanism of hydrophobic control in reactions of microbial tryptophanase the direct effect of the solvent hydrophobicity on affinities of amino acid inhibitors was first examined. Values of inhibition constants (K_i) for a variety of amino acids were determined in 37.5% aqueous methanol, and no general correlation between the change of K_i, on passing from water to aqueous methanol, and amino acid hydrophobicity was found. The solvent effects on the separate stages of the external aldimine formation (K_D) and deprotonation to form a quinonoid intermediate (K_q) were determined for the reactions of tryptophanase with 2-oxindolyl- -alanine and -alanine by stopped-flow technique. For 2-oxindolyl- -alanine, which is a close transition-state analogue for the enzyme reaction with natural substrate, the decrease in the affinity in aqueous methanol is associated exclusively with the α-proton abstraction stage but not with the preceding formation of external aldimine. We conclude that the environment of amino acid side chains in the active site cannot be considered to be permanently hydrophobic irrespective of the bound amino acid. We suggest that complexes of tryptophanase with amino acids may exist either in a hydrophobic, presumably “closed”, conformation, where bound amino acids are isolated from the solvent, or in an accesible to solvent, “open”, conformation, depending on the structure of the bound amino acid and stage of the catalytic mechanism. For 2-oxindolyl- -alanine the transfer from an open to a closed conformation probably accompanies deprotonation of the external aldimine. The change of the active site hydrophobicity may provide an efficient way of modulating the relative acid–base properties of the catalytic groups to ensure the movement of protons in the “correct” direction depending on the elementary stage of catalysis.     

Immunomodulatory effect of selenosemicarbazides and selenium inorganic compounds, distribution in organs after selenium supplementation

Antioxidant properties of selenium producing a protective barrier against free radicals play an important role in numerous metabolic and immunologic processes associated with oxidation- reduction reactions which take place during intracellular digestion of phagocyted bacteria. The aim of our study was to examine the properties of an organic compound of selenium, 4-(o-tolilo)- selenosemicarbazide of p-chlorobenzoic acid in terms of its retention in organs, effect on erythropoesis and phagocytic abilities of neutrophiles as well as antioxidant properties in neutrophiles tested with NBT test. This compound as well as inorganic sodium selenate was given to Swiss mice at the dose of 10^–3 g Se/kg for the period of 10 days. The concentrations of selenium in livers of mice treated with sodium selenate and selenosemicarbazide were found to be higher than in controls (18,7 g lg^–1 and 23.2 g lg^–1 vs. 12 g lg^–1, respectively). Analysis of blood cells count has shown a significant decrease in neutrophile levels in both groups treated with selenium. The influence of selenium compounds on phagocytosis and especially NBT test has been determined (3.8% of positive cells in the controls vs. 2.2% and 0.9% in the groups treated with sodium selenate and selenosemicarbazide, respectively). Our preliminary investigations suggest that selenosemicarbazides are biologically active compounds and can modify neutrophile functions.     

Production of trisaccharide from lactose using β-galactosidase from Bacillus circulans modified by glutaraldehyde

Summary Free amino groups of -galactosidase-1-from Bacillus circulans were partially modified using different glutaraldehyde concentrations to increase trisaccharide production from lactose. Glutaraldehyde of 0.01%–0.03% modified 15%–40% of the free amino groups of the enzyme. The maximum yield of trisaccharide increased from 6% to 12% depending upon the degree of modification with 25% conversion of 127 mM lactose. Modification of 50% of the free amino groups of the enzyme using 0.05% glutaraldehyde produced a considerable amount of tetrasaccharide along with trisaccharide even at the initial stage of the reaction.     

Adventitious shoot regeneration from leaf explants of tissue cultured and greenhouse-grown raspberry

Adventitious shoot regeneration was observed using leaf-petiole explants from shoot-proliferating cultures of Comet red raspberry (Rubus idaeus L.). A maximum regeneration rate of 70% (3.7 shoots/explant) was obtained using 4.5–9.1 M (1–2 mg l^–1) N-phenyl-N-1,2,3-thiadiazol-5-ylurea (thidiazuron or TDZ) with 2.5–4.9 M (0.5–1 mg l^–1) 1H-indole-3-butanoic acid (IBA) or 2.3 M (0.5 mg l^–1) TDZ with 4.9 M (1 mg l^–1) IBA in modified Murashige-Skoog medium. TDZ was more effective than N-(phenylmethyl)-1H-purin-6-amine (BA) at promoting regeneration in combinations tested with IBA (maximum 50% regeneration rate; 1.8 shoots/explant). Variation in the agar concentration or incubation temperature, orientation or scoring of the leaf-petiole explants and use of separate leaf or petiole explants had no effect on shoot regeneration. Incubation in the dark for 1, 2 or 3 weeks prior to growth in the light did not influence the percent regeneration rate but depressed the number of adventitious shoots. Explant source, from micropropagated shoots or greenhouse-grown plants, had an effect on shoot regeneration that was genotype dependent. Only 8 of 22 (36%) raspberry cultivars were capable of regeneration from leaf explants derived from greenhouse-grown plants.     

Chemical cleavage of bovine beta-lactoglobulin by BNPS-skatole for preparative purposes: comparative study of hydrolytic procedures and peptide characterization

A comparative study of various procedures for tryptophanyl peptide bond cleavage by BNPS-skatole [2-(2-nitrophenyl)-3-methyl-3-bromoindolenine] was carried out on native and on reduced and alkylated bovine -lactoglobulin (BLG). The reaction yield and the composition of the derived products were studied in acetic acid, trifluoroacetic acid (TFA), and ethanol/TFA. For BNPS-skatole removal, extraction by water or ethyl ether was compared with dialysis and gel filtration. The three expected peptides (1–19, 20–61, 62–162) and incomplete cleaved fragments (1–61, 20–162) were separated and characterized by electrophoresis, reverse-phase high-performance liquid chromatography, and mass spectrometry. The highest hydrolysis yield (67.4%) occurred with native BLG cleaved in 88% acetic acid at 47°C for 60 min. Subsequent water extraction and gel filtration led to total recovery of the material, but reagent elimination was only quantitative after gel filtration. Cleavage specificity was ensured by mass spectrometry and the amino acid composition of peptides 1–19 and 62–162. The chemical side reactions identified are discussed.