Bilirubin dehydrogenase,an enzyme in Aspergillus ochraceus IB-3 useful for diagnostic measurement of bilirubin

Bilirubin dehydrogenase, a membrane-bound enzyme that catalyzes the one-step oxidation of ditaurobilirubin and bilirubin to ditaurobiliverdin and biliverdin, respectively, in the presence of an electron acceptor, was found in Aspergillus ochraceus IB-3, and purified from the membrane fraction through solubilization by Triton X-100. Phenazine and quinone derivatives acted as electron acceptors. Accumulation of ditaurobiliverdin and biliverdin by enzyme catalysis increased the absorbance at 660 nm, which is far from the range of wavelengths affected by serum ingredients. The enzyme selectively oxidized ditaurobilirubin at low pH, so changes in the reaction pH enable the enzyme to discriminate between the bilirubin fractions ditaurobilirubin (an example of conjugated bilirubin) and bilirubin (an example of unconjugated bilirubin). Using the enzyme, 2 to 80 microM of ditaurobilirubin were measured accurately by monitoring the changes in absorbance at 660 nm.     

Bilirubin Dehydrogenase,an Enzyme in Aspergillus ochraceus IB-3 Useful for Diagnostic Measurement of Bilirubin

Bilirubin dehydrogenase, a membrane-bound enzyme that catalyzes the one-step oxidation of ditaurobilirubin and bilirubin to ditaurobiliverdin and biliverdin, respectively, in the presence of an electron acceptor, was found in Aspergillus ochraceus IB-3, and purified from the membrane fraction through solubilization by Triton X-100. Phenazine and quinone derivatives acted as electron acceptors. Accumulation of ditaurobiliverdin and biliverdin by enzyme catalysis increased the absorbance at 660 nm, which is far from the range of wavelengths affected by serum ingredients. The enzyme selectively oxidized ditaurobilirubin at low pH, so changes in the reaction pH enable the enzyme to discriminate between the bilirubin fractions ditaurobilirubin (an example of conjugated bilirubin) and bilirubin (an example of unconjugated bilirubin). Using the enzyme, 2 to 80 μM of ditaurobilirubin were measured accurately by monitoring the changes in absorbance at 660 nm.     

Cleavage of the taurine conjugate of 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholestan-26-oic acid by rat fecal bacteria.

This paper describes a method for the hydrolysis of the taurine conjugates of the 25R and the 25S diastereoisomers of 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholestan-26-oic acid (THCA) with retention of original configuration of C-25. Rat fecal suspensions were incubated with the taurine conjugate of THCA for 5 and 60% of the free THCA was recovered. When bile from Alligator mississippiensis, which contains mostly the taurine conjugate of THCA, was analyzed by this method, THCA was obtained with the 25R configuration.     

Occurrence of 2-Aminobutanoic Acid in the Incubation Medium of Mixed Rumen Ciliate Protozoa1

An unknown, ninhydrin-positive substance detected on paper chromatograms of the endogenous metabolites of mixed rumen ciliate protozoa was isolated and purified by column chromatography with ‘Dowex’ 50-X8 resin and identified as 2-aminobutanoic acid (α-amino-n-butyric acid) on the basis of elementary analysis, mass spectrometry, paper chromatography, infrared spectrometry, and melting point.     

Purification and properties of LIQ 4, an antibacterial substance produced by Streptococcus faecalis var. liquefaciens K4

An antibacterial substance (LIQ 4) produced by Streptococcus faecalis var. liquefaciens K 4 was isolated in extracellular and cell associated form. It markedly inhibited the growth of Gram-positive bacteria, whereas only a few Gram-negative bacteria were susceptible. LIQ 4 was purified by hydrophobic chromatography (Servachrome XAD-2; octyl-Sepharose CL-4B; Sephadex LH 60) and Sephacryl S-200. TLC yielded a fluorescent spot as the active component and several inactive ninhydrin-positive substances. These contaminating peptides strongly adsorbed to LIQ 4 and could only be removed by repeated reversed phase HPLC. Furthermore, HPLC separated LIQ 4 into seven closely related substances. All showed strong fluorescence under UV light, stained yellow with ninhydrin, and contained aspartate and lysine after acid hydrolysis. The molecular weight was estimated by Amicon ultrafiltration to be less than 2000. LIQ 4 was stable at 80 degrees C (30 min) and pH 2, but considerably inactivated above pH 8. It was apparently affected by proteolytic enzymes, but the activity could be fully restored upon heating.     

The trimethylsilylation reactions of hexosamines, and gas-chromatographic separation of the derivatives

Several methods for trimethylsilylation were applied to the 2-amino-2-deoxy-hexoses, and the resulting derivatives were characterized by gas-liquid chromatography as to retention index, response factor, and degree of substitution on the amino group. Conditions were found for replacing none, one, or both of the amino protons with trimethylsilyl groups. The average response-factor for the trimethylsilyl derivatives was found to be 6.27 g of docosane per mole of hexosamine, or 1.13 mg of docosane per mg of hexosamine. One of the methods investigated was applied to the determination of hexosamines in acid hydrolyzates of glycosaminoglycans. The 2-acetamido-2-deoxy derivatives were also studied, but the several derivatives have not yet been identified.     

Effects of Pregnancy on the Contents of Water, Taurine, and Total Amino Nitrogen in Rat Cerebral Cortex

Plasma osmolality and the levels of water, taurine, and total amino nitrogen (detected as ninhydrin-positive substances) have been measured in the cerebral cortices of nonpregnant and 19-day pregnant Wistar rats. Plasma osmolality fell by 11 mosmol/kg during pregnancy. Brain water content remained unaltered, but levels of taurine and ninhydrin-positive substances fell by 48.5 and 21.9%, respectively. It is suggested that one way in which brain cells are prevented from swelling during the mild hypoosmolality of pregnancy is through loss of cellular amino nitrogen, particularly taurine.     

Bacereutin, an antifungal antibiotic isolated from metabolites of Bacillus cereus CHU 130

An antifungal metabolite, bacereutin, was isolated from culture filtrate of Bacillus cereus CHU 130. The bacterium was isolated from soils collected in Changhwa County, Taiwan, and was grown in soybean meal-mannitol broth for production of the antibiotic metabolite. The antibiotic metabolite was isolated by adsorption column chromatography of Amberite XAD-2 and was purified by passing through the chromatographic columns packed with Dowex 50W-X8, Sephadex LH 20 and Biogel P-2. The antibiotic metabolite was soluble in water and 87% acetone, and was slightly soluble in methanol, but was not dissolved in n-propanol, n-butanol, acetone, benzene and ethyl acetate. The antibiotic metabolite was a heat-stable and ninhydrin-positive substance. The antibiotic activities of bacereutin were tested by means of the agar-diffusion plate method. The antibiotic metabolite inhibited the growth of Saccharomyces cerevisiae CHU 1, Paecilomyces variotii CHU 6, Rhizomucor miehei CHU 40 and Fusarium oxysportum CHU 98. Bacereutin was a ninhydrin-positive antifungal antibiotic.     

The isolation, partial characterization, and biosynthesis of the paragonial substances, PS-1 and PS-2 of Drosophila funebris

In methanolic extracts of accessory glands (paragonia) from Drosophila funebris, two specific, ninhydrin-positive substances, PS-1 and PS-2, were found. PS-1 and PS-2 were isolated by column chromatography. PS-1 consists of 27 amino acid residues. Two forms of PS-1 are present in the ratio of 7:3 which differ only in the content of valine and leucine. Fractions containing partially purified valine-PS-1 and leucine-PS-1, respectively, have the same biological activity. All males in the population synthesize both forms of PS-1. PS-2 is a low molecular weight substance containing glycine and ammonia as ninhydrin-positive components and carbohydrate as indicated by several sugar tests. In vitro studies showed that copulation provides the stimulus for enhanced synthesis of paragonial substances.     

Immunological Approach to the Detection of Taurine and Immunocytochemical Results

An immunological approach to the detection of taurine resulted in antibodies specific enough to be used for immunocytochemical studies. The experimental conditions were similar to those previously described for raising antibodies against some small-sized neurotransmitter molecules: antisera were obtained from rabbits immunized with taurine conjugated to carrier proteins via glutaraldehyde and purified by adsorption on the glutaraldehyde-treated protein carriers. Antibody affinity and specificity were determined in competition experiments between conjugated taurine and other conjugated amino acids or derivatives by enzyme-linked immunosorbent assay. The resulting cross-reactivity ratios, calculated at half-displacement, showed conjugated taurine to be the best recognized compound. Given the molecular structure of taurine and the method used to prepare the conjugate, it seemed necessary to perform an oxidation step. However, adsorption of antisera on reoxidized or nonreoxidized taurine conjugates suggested that reoxidation did not make a significant difference. Immunocytochemical application of the sera revealed populations of strongly immunopositive nerve cells in the cerebellum, striatum, and septum. The results confirmed that antitaurine antibodies can be used as specific tools for a better understanding of the role of taurine in the central nervous system.     

Fluorescent derivatives of bile salts. II. Suitability of NBD-amino derivatives of bile salts for the study of biological transport.

Interaction of unconjugated and taurine-conjugated NBD-amino-dihydroxy-5 beta-cholan-24-oic acids bearing the fluorophor in the 3 alpha, 3 beta, 7 alpha, 7 beta, 12 alpha, or 12 beta position with albumin results in a small hypsochromic shift of the emission maximum and an increase in quantum yield, suggesting binding by hydrophobic interactions. The different unconjugated fluorescent bile salt derivatives are metabolized by intact rat liver in different ways. The unconjugated 3 beta-NBD-amino derivative is completely transformed to its taurine conjugate and secreted as such, whereas the 3 alpha-NBD-amino derivative is completely transformed to a polar fluorescent compound not identical with its taurine conjugate. The unconjugated 7 alpha- and 7 beta-NBD-amino derivatives are only partially conjugated with taurine and mainly secreted in unmetabolized form. The unconjugated 12 alpha- and 12 beta-NBD-amino derivatives are not at all transformed to their taurine conjugates, but are partially metabolized to unidentified compounds. They are predominantly secreted as the unmetabolized compounds. In contrast to the unconjugated derivatives, all taurine-conjugated fluorescent bile salt derivatives are secreted into bile unmetabolized. With the exception of the 3 alpha-compound, all synthesized taurine-conjugated fluorescent derivatives interfere with the secretion of cholyltaurine. Differential photoaffinity labeling studies using (7,7-azo-3 alpha,12 alpha- dihydroxy-5 beta-cholan-24-oyl)-2'-[2'-3H(N)]aminoethanesulfonate as a photolabile derivative revealed that in liver cells all fluorescent bile salt derivatives interact with the same polypeptides as the physiological bile salts. The hepatobiliary transport of taurine-conjugated NBD-amino bile salt derivatives is, due to hydrophobic interactions, accompanied by an increase in fluorescence intensity which is favorable for the study of biological bile salt transport by fluorescence microscopy.     

Occurrence,localization, and possible significance of an ornithine-containing lipid in Paracoccus denitrificans

A ninhydrin-positive, phosphorus-negative lipid from Paracoccus denitrificans ATCC 13543 has been isolated and purified by mild alkaline methanolysis followed by silicic acid column chromatography and preparative thin-layer chromatography. The lipid was identified as an ornithine-containing lipid. The major ester-linked fatty acid was cis vaccenic acid. Major amide-linked fatty acids were 3-OH-20:1 and 3-OH-18:0. Ornithine-containing lipid was a major lipid component of P. denitrificans. Phospholipids made up about 57% and ornithine-containing lipid about 14% of the weight of the total lipid of the organism. The ratios of lipid ornithine: lipid phosphorus were 0.23, 0.65 and 0.58 in cytoplasmic membrane, outer membrane, and an NaCl extract, which is thought to represent chiefly outer membrane, respectively. Thus ornithine-containing lipid appears to be present in larger amounts in outer membrane than cytoplasmic membrane. No substantial variations in lipid ornithine levels were noted in stationary phase versus exposnential phase organisms, organisms grown in complex medium versus organisms grown in minimal medium with and without amino acid supplements, or in organisms grown in low phosphate-containing medium.Non standard abbreviations TLC thin-layer chromatography - Tris-HCl tris(hydroxymethyl)aminomethane hydrochloride - TMS trimethylsilyl - TFA triluoroacetyl - NPPN ninhydrin-positive, phosphorus-negative - ECL equivalent chain length     

Identification of a taurine transport inhibitory substance in sesame seeds

An ethanol extract from sesame seeds inhibited the taurine uptake in human intestinal epithelial Caco-2 cells. The uptake of such alpha-amino acids as leucine and glutamic acid was not inhibited by the extract, indicating that this inhibition is specific to the taurine uptake. The unknown inhibitor in the sesame extract was purifled by reversed-phase HPLC by monitoring the inhibitory effect on taurine uptake. The isolated substance was identified as lysophosphatidylcholine, linoleoyl (Lyso-PC), by NMR and MS analysis. Lyso-PC inhibited the taurine uptake in a dose-dependent manner with an IC50 value of approximately 200 microM. Although Lyso-PC is known to be a surface active and cell lytic compound, neither damage nor loss of integrity of the Caco2 cell monolayer was apparent after treating with 200 microM Lyso-PC. Inhibition was observed by incubating cells with Lyso-PC for only 1 min prior to the uptake experiments. These results suggest the direct effect of Lyso-PC on the cell membrane to be the main mechanism for this inhibition. Lyso-PC may play a role in the regulation of certain intestinal transporters.     

Physiological amino acids in brain tissue of the lepismatids,Lepisma saccharina and Thermobia domestica (Insecta,Thysanura)

1. The free (physiological) amino acid profile in the brain tissue of Lepisma saccharina and Thermobia domestica (Thysanura, Lepismatidae) was investigated.2. Nitrogenous waste products (ammonia and urea) together constituted 28% of the total ninhydrinpositive compounds for both species.3. GABA accounted for 3% of the total ninhydrin-positive compounds in the brain of L. saccharina, and T. domestica.4. Glutamate comprised 7% of the total ninhydrin-positive compounds in the brain of L. saccharina, and 8% in T. domestica.5. The most abundant amino acids were alanine, proline, arginine and taurine.6. The possible role of amino acids as neurotransmitters and/or modulators of neurotransmitter activity is discussed as well as the comparative free amino acid composition of the brain tissues of various arthropod groups.     

Characteristics of taurine transport in rat liver lysosomes

Taurine (2-aminoethanesulfonic acid) is a unique sulfur amino acid derivative that has putative nutritional, osmoregulatory, and neuroregulatory roles and is highly concentrated within a variety of cells. The permeability of Percoll density gradient purified rat liver lysosomes to taurine was examined. Intralysosomal amino acid analysis showed trace levels of taurine compared to most other amino acids. Taurine uptake was Na(+)-independent, with an overshoot between 5-10 minutes. Trichloroacetic acid extraction studies and detergent lysis confirmed that free taurine accumulated in the lysosomal space. Kinetic studies revealed heterogeneous uptake with values for Km1 = 31 +/- 1.82 and Km2 greater than 198 +/- 10.2 mM. The uptake had a pH optimal of 6.5 and was stimulated by the potassium specific ionophore valinomycin. The exodus rate was fairly rapid, with a t1/2 of 5 minutes at 37 degrees C. Analog inhibition studies indicated substrate specificity similar to the plasma membrane beta-alanine carrier system, with inhibition by beta-alanine, hypotaurine, and taurine. alpha-Alanine, 2-methylaminoisobutyric acid (MeAIB), and threonine were poor inhibitors. No effects were observed with sucrose and the photoaffinity derivative of taurine NAP-taurine [N-(4-azido-2-nitrophenyl)-2-aminoethanesulfonate]. In summary, rat liver lysosomes possess a high Km system for taurine transport that is sensitive to changes in K+ gradient and perhaps valinomycin induced diffusional membrane potential. These features may enable lysosomes to adapt to changing intracellular concentrations of this osmotic regulatory substance.     

Reduction of bilirubin ditaurate by the intestinal bacterium Clostridium perfringens

Bilirubin is degraded in the human gut by microflora into urobilinoids. In our study we investigated whether the bilirubin-reducing strain of Clostridium perfringens can reduce bilirubin ditaurate (BDT), a bile pigment of some lower vertebrates, without hydrolysis of the taurine moiety. C. perfringes was incubated under anaerobic conditions with BDT; reduction products were quantified by spectrophotometry and separated by TLC. Based on Rf values of BDT reduction products and synthetic urobilinogen ditaurate, three novel taurine-conjugated urobilinoids were identified. It is likely that bilirubin-reducing enzyme(s) serve for the effective disposal of electrons produced by fermentolytic processes in these anaerobic bacteria.     

Respiratory behaviour of sea-urchin spermatozoa. II. Sperm-activating substance obtained from jelly coat of sea-urchin eggs.

A sperm-activating substance (SAS) was obtained from the jelly coat of sea-urchin ova and its chemical properties were investigated in three sea-urchin species. The SAS was partially purified from the jelly coat of Pseudocentrotus eggs through several steps of purification by procedures consisting of charcoal adsorption, ion-exchange chromatography on DEAE-Sephadex A-25 column, and gel-filtration on Sephadex G-15 columns. The partially purified SAS was found to contain a ninhydrin-positive material and is inactivated by pronase digestion. The molecular weight of SAS was estimated as about 630 by gel-filtration through Sephadex G-25 and the isoelectric-point of SAS is located at about pH 5.3 by isoelectrofocusing method. The SAS is non-volatile, alcohol-soluble, and labile in a diluted alkaline or acid solution. The origin of SAS is discussed.     

Purification and characterization of bile acid-CoA:amino acid N-acyltransferase from rat liver

An in vitro study of bile acid-CoA:amino acid N-acyltransferase activity of rat liver was undertaken in order to determine whether separate amino acid-specific enzymes catalyzed the formation of glycine and taurine conjugates of bile acids as postulated by others. Polyacrylamide gel electrophoresis of 200-fold purified enzyme localized the glycine- and taurine-dependent activities to a single band. Both activities were optimal at pH 7.8 and showed similar loss of activity at pH 6.0, pH 9.0, in the presence of 5,5'-dithiobis(2-nitrobenzoic acid), and at temperatures exceeding 50 degrees. With the purified fraction, Km for glycine was 31 mM and Km for taurine was 0.8 mM. Km for several bile acid-CoA substrates was approximately 20 micron and independent of the amino acid acceptor. Only amino acids with terminal alpha- or beta-amino groups were active as acyl acceptors. Acyl donors were limited to bile acid-CoA derivatives. The data support the conclusion that the rat has a single bile acid-CoA:amino acid N-acyltransferase. The substrate kinetics are consistent with previous observations that taurine conjugates predominate in rat bile at normal hepatocellular concentrations of glycine and taurine.     

Bile acid metabolism in mammals. VIII. Biliary secretion of cholylarginine by the isolated perfused rat liver.

In studies of cholic acid metabolism using the isolated perfused rat liver system, an unknown conjugate of cholic acid was observed. This conjugate comprised 15-27% of the biliary bile acids in these experiments, was less polar than cholylglycine on thin-layer chromatography using butanol, acetic acid, and water, and had an apparent molecular weight greater than that of cholyltaurine on gas-liquid chromatography. Amino acid analysis of the hydrolyzed conjugate demonstrated the presence of arginine. Perfusion studies with radioactive arginine, and mass spectrometric analysis proved that the conjugate was cholylarginine. Secretion of this conjugate does not represent a deficiency of available glycine and taurine.     

Production and purification of bacilysin

1. Bacilysin, a hydrophilic substance formed by certain aerobic spore-forming bacteria that causes lysis in cultures of growing staphylococci, has been produced in aerated cultures of a strain of Bacillus subtilis (A14). A chemically defined medium was used, which contained glucose, Czapek-Dox salts and ferric iron. Production of bacilysin occurred, after a lag, while the culture was still undergoing rapid growth. 2. Bacilysin was adsorbed from the culture medium on Zeo-Karb 225 (SR5) (H(+) form) and eluted with aqueous pyridine. The crude material was purified by chromatography in pyridine-acetate buffers on columns of Dowex 50 (X2) and Dowex 50 (X8) respectively and by chromatography in aq. 70% (v/v) propan-2-ol on Sephadex G-25. 3. Purified bacilysin behaved as a single ninhydrin-positive substance when subjected to chromatography on paper in butan-1-ol-acetic acid-water and to electrophoresis on paper at pH4.5 or pH1.8. At pH4.5 the substance behaved as though it had no net change and at pH1.8 it migrated towards the cathode.