2-aminoethanesulfonic Acid Research Articles

Taurine, A Wonderful Molecule: A Review Article

Taurine chemically known as 2 aminoethanesulfonic acid; NH2CH2CH2SO3H it’s a non essential amino acid, due to absence of carboxyl group it does not participate in protein synthesis, it does not metabolized and thus not involved in gluconeogenesis, thereby not constituting a direct energy source, This wonderful molecule was discover in 1827 by two German scientist Tiedemann and Gmelin from bile of ox (Bos taurus), Ten years later, this amino acid got its name as Taurine by Demarcay, and 20 years later Jacobsen and Smith discovered that its structure contains sulfur. In a wide variety of invertebrate and vertebrate tissues the natural occurrence of taurine has been recognized, It is also present in plants algae and fungi. In this review we try to cover all possible beneficial role of taurine.

Organizing Uniform Phase Distribution in Methylammonium-Free 1.77eV Wide-Bandgap Inverted Perovskite Solar Cells.

Disordered crystallization and poor phase stability of mixed halide perovskite films are still the main factors that compromise the performance of inverted wide bandgap (WBG; 1.77eV) perovskite solar cells (PSCs). Great difficulties are evidenced due to the very different crystallization rates between I- and Br-based perovskite components through DMSO-alone assisted anti-solvent process. Here, a zwitterionic additive strategy is reported for finely regulating the crystal growth of Cs0.2 FA0.8 Pb(I0.6 Br0.4 )3 , thereby obtaining high-performance PSCs. The aminoethanesulfonic acid (AESA) is introduced to form hydrogen bonds and strong PbO bonds with perovskite precursors, realizing the complete coordination with both the organic (FAI) and inorganic (CsI, PbI2 , PbBr2 ) components, balancing their complexation effects, and realizing AESA-guided fast nucleation and retarded crystallization processes. This treatment substantially promotes homogeneous crystal growth of I- and Br-based perovskite components. Besides, this uniformly distributed AESA passivates the defects and inhibits the photo-induced halide segregation effectively. This strategy generates a record efficiency of 19.66%, with a Voc of 1.25V and FF of 83.7% for an MA-free WBG p-i-n device at 1.77eV. The unencapsulated devices display impressive humidity stability at 30±5% RH for 1000h and much improved continuous operation stability at MPP for 300h.

Structural insights into interactions of new polymeric (μ–oxo) bridged Cu(II) complexes of taurine with yeast tRNA by spectroscopic and computational approaches and its application towards chemoresistant cancer lines

RNA-targeted drugs are considered as safe treatment option for the cure of many chronic diseases preventing off-targeted delivery and acute toxic manifestations. FDA has approved many such RNA therapies in different phases of clinical trials, validating their use for the treatment of various chronic diseases. We report herein, new water-soluble (μ–oxo) bridged polymeric Cu(II) complexes of taurine (2–aminoethane sulfonic acid) complexes 1 and 2. The therapeutic potency of 1 and 2 was ascertained by studying biophysical interactions with tRNA/ct-DNA. The experimental results demonstrated that the complexes interacted avidly to nucleic acids through intercalation mode depicting a specific preference for tRNA in comparison to ct–DNA and, moreover 2 showed higher binding propensity than 1. The electrophoretic behaviour of the complexes with plasmid pBR322 DNA and tRNA were examined by gel mobility assay that revealed a concentration-dependent activity with complex 2 performing more efficient cleavage as compared to complex 1. Cytotoxicity results on cancer cell strains displayed higher cytotoxicity than complex 1 against treated cancer cells. The synthesized copper(II) taurine complexes have met the basic criteria of anticancer drug design as they are structurally well-characterized, exhibiting good solubility in water, lipophilic in nature with superior intercalating propensity towards tRNA and cytotoxic in nature.

EFFECT OF TAURINE ON MANIFESTATION OF AUDIOGENIC EPILEPSY IN RATS WITH PENDULUM MOVEMENTS

A decrease of taurine in hippocampus of the line of rats with pendulum movements (PM), predisposed to audiogenic epilepsy, was shown. Taurine (aminoethanesulfonic acid) is known to be an anticonvulsant drug. The aim of the present work was to verify the predictive validity of taurine in rats with pendulum movements (PM). In neonatal period the exogenous taurine administration did not influence a convulsive activity at the age of 1.5 and 3 months in PM rats. The increase in the number of audiogenic seizures after taurine injections was found in adolescent period in 1.5 months and in prolonged point – in 3 months. The number of abortive seizures decreased under acute injection of taurine in adult PM rats, but the level of ictal and postictal indicators restored one month later, at the age of 4 months. Obtained results indicate the absence of effect of taurine administered to rats in the neonatal age, while at the long-term scale, the rats showed the increasing seizure activity under the action of taurine in adolescent period and confirm the predictive validity of this drug in adult PM rats.

Efficient persulfate activation catalyzed by pyridinic N, C OH, and thiophene S on N,S-co-doped carbon for nonradical sulfamethoxazole degradation: Identification of active sites and mechanisms

• N,S-co-doped carbonaceous persulfate activators are synthesized. • Complete SMX removal and 80% mineralization rate are achieved. • N/S atomic ratio largely affects the catalytic performance. • Pyridinic N, C OH, and thiophene S act as the active sites. • Degradation of SMX is mediated by nonradical 1 O 2 . Nitrogen- and sulfur-co-doped carbons were prepared by pyrolyzing chitosan and aminoethanesulfonic acid sodium, and used to activate persulfate (PS) for sulfamethoxazole (SMX) degradation. Sulfur incorporation into nitrogen-doped carbon (NC) enhanced the catalysis. Moreover, the catalytic properties were largely affected by the N/S atomic ratio. At the N/S ratio of 8.06, the best performance could be achieved (NSC-0.5, 0.08317 min −1 ). Correspondingly, complete SMX removal, 80% mineralization, and 74% PS utilization were found within 120 min. The NSC-0.5/PS system worked effectively at strong acidic and weak basic conditions (pH ≈ 3–9). The pyridinic N, C OH, and thiophene S were identified to be the active sites. The above three units could transfer electron to PS to generate superoxide radical (O 2 − ). The resulting O 2 − reacted with H 2 O or self-recombination with H + to generate singlet oxygen ( 1 O 2 ). However, the structural defects might not work in the course of PS activation. Nonradical singlet oxygen ( 1 O 2 ) was mainly in charge of SMX oxidation. The toxicity of degradation system, influence of real water matrix, and reusability of the catalyst were investigated comprehensively. Nine possible degradation pathways were proposed. In addition, the NSC-0.5/PS system was also capable of degrading other antibiotics (ciprofloxacin, sulfamonomethoxine) and non-antibiotics (bisphenol A, rhodamine B). This work highlights the significant roles of pyridinic N, C OH, and thiophene-S in PS activation for catalytic degradation organic contaminants, and presents a feasible approach to construct efficient carbon-based persulfate activators.

Turbinaria ornata and its associated epiphytic Bacillus sp. A promising molecule supplier to discover new natural product approaches

Marine ecosystems are highly dependent on macroalgea in providing food and shelter for aquatic organisms, interacting with many bacteria and mostly producing secondary metabolites of potent therapeutic antibacterial property. Screening of marine microbial secondary metabolites of valuable biotechnological and therapeutical applications are now extensively studied. In this study, Bacillus spp. identified by DNA sequencing and found associated with Turbinaria ornata, was screened and characterized for its cell free supernatant (CFS) possible antimicrobial and antibiofilm applications. Among the 7 microbial isolates tested, CFS greatly affected Bacillus subitilis (12 mm) and inhibited equally the yeast isolates Candida albicans, Candida tropicalis and Candida glabrata (10 mm) and had no or negligible effect on S.aureus, E.coli, P. aeruginosa. As for the CFS antibiofilm activity, no difference was revealed from the positive control. Algal crude extracts (methanol, acetone and aqueous), on the other hand, were similarly tested for their antimicrobial activity against the seven microbial isolates, where highest activity was observed with the aqueous crude extract against Staphylococcus aureus(10 mm) and Pseudomonas aeruginosa (9 mm) compared to the negligible effects of methanol and acetone crude extracts. Chemical analysis was performed to reveal the major constituents of both crude algal extracts and Bacillus spp. CFS. FTIR spectrum of the bacterial CFS indicated the presence of bacteriocin as the major lipopeptide responsible for its biological activity. Whereas, methanol and water crude algal extract GC–MS spectra revealed different chemical groups of various combined therapeutical activity mainly Naphthalene, amino ethane-sulfonic acid, pyrlene, Biotin and mercury chloromethyl correspondingly. Thus, the present study, demonstrated the moderate activity of both crude algal extract and the bacterial CFS, however, further investigations are needed for a better biological activity.

BUFFER SOLUTIONS BASED ON TAURINE

The acid-base interaction in the aminoethanesulfonic acid (taurine, Tau) – potassium aminoethanesulfonate – water system was studied by pH-, redox- and conductometric methods in the temperature range 293–313 K. The ion-molecular composition of NH2CH2CH2SO3H –NH2CH2CH2SO3K – H2O system was calculated. It is shown aminoethanesulfonic acid in aqueous solutions to exist at the ratio CKOH/QTau < 0.5 mainly in the zwitterion form similar to systems with glycine, aminomethanesulfonic acid and its N‑alkylated derivatives. The content of the aminoethanesulfonate anion is directly proportional to the CKOH/QGly ratio. The studied system ionic strength and acid-base dissociation constant for the second stage of the aminoethanesulfonic acid concentration and temperature dependences were determined. The ionic strength values at the isoelectric point (mi.p.)are directly proportional to С0Tau and practically do not depend on the temperature within the error for the same series С0Tau and С0KOH .The pH limits of the buffer action are determined and the buffer capacity of these systems is estimated. It has been established that effective buffer zones of Tau aqueous solutions can to maintain acidity in the higher then physiological pH range at temperature range 293–313 K. The buffer capacity of NH2CH2CH2SO3H – NH2CH2CH2SO3K – H2O system exceeds the analogous values of YNHCH2SO3H – YNHCH2SO3K – H2O (Y = H, CH3, CH2CH2OH, C(CH3)3 and C2H5C6H5) systems. The obtained data on the buffer capacity of the aminoethanesulfonic acid – potassium aminoethanesulfonate – water system can be used in chemical analysis, microbiological and biochemical studies, and the acidity data of the solutions studied can simulate the chemisorption of acid gases (carbon and sulfur dioxides).

Synthesis and Study of Modified Polyaspartic Acid Coupled Phosphonate and Sulfonate Moieties As Green Oilfield Scale Inhibitors

The petroleum industry has strived for several years to explore environmentally friendly scale inhibitors with no acute environmental impact. Well-known industrial biodegradable polyaspartic acid is widely used as a potent scale inhibitor (SI) against various inorganic scales in industrial circulating cooling water and topside petroleum applications. However, polyaspartic acid showed weak thermal stability at the petroleum reservoir temperatures. Here, we attempt to develop a new class of polyaspartic acid for squeeze treatment applications under harsh conditions. In this project, a series of modified polyaspartic acid, including pendant anionic functional moieties (phosphonate and sulfonate) were synthesized and investigated as new SIs to inhibit the calcium carbonate (calcite, CaCO3) and barium sulfate (barite, BaSO4) scales under oilfield conditions. These classes were synthesized via aminolysis of polysuccinimide with nucleophilic amine reagents under alkaline conditions. The products are polyaspartic acid-capped aminomethylene phosphonic acid (SI-2), polyaspartic acid-capped bisphosphonic acid (SI-3), polyaspartic acid-capped aminomethanesulfonic acid (SI-4), and polyaspartic acid-capped aminoethanesulfonic acid (SI-5), as well as in-house synthesized polyaspartic acid (SI-1). The scale inhibition activities of these compounds against carbonate and sulfate scales were determined using the dynamic scale loop test at 100 °C and 80 bar. Furthermore, the long-term thermal aging and calcium tolerance experiments were also investigated. It was found that polyaspartic-acid-capped aminomethylene phosphonic acid (SI-2) gave outstanding calcite scale inhibition performance and showed excellent thermal stability at 130 °C for 7 days compared to SI-1 and other modified SIs (SI-3-SI-5). This phosphonated polymer also exhibited superior calcium tolerance performance with Ca2+ ions up to 100 ppm, and moderate performance in the range of 1000–10 000 ppm calcium ions. This project highlights the success of designing and developing a new environmentally friendly calcite SI-based polyaspartic acid under harsh oilfield conditions.

Determination of Total Proteinogenic Amino Acids and Taurine by Pre-column Derivatization and UHPLC: Single Laboratory Validation, First Action Official MethodSM 2019.09.

A method has been developed and validated for selective, accurate, and precise determination of total proteinogenic amino acids and taurine from infant formula and adult/pediatric nutritional formulas (powders, ready-to-feed liquids, and liquid concentrates). The method was reviewed by the AOAC INTERNATIONAL SPIFAN Expert Review Panel (ERP) during the 133rd AOAC Annual Meeting and Expo on September 7, 2019 in Denver, CO, USA, and was recommended to First Action Official MethodsSM status. The method involves protein hydrolysis to amino acids, a simple pre-column derivatization of amino acids and separation of derivatized amino acids by UHPLC. The quantification of amino acids is performed by multi-point calibration using norvaline as the internal standard. The analytical method is capable of quantitative determination for 22 proteinogenic amino acids, but cannot be used to quantitate tryptophan, which is destroyed during the acid hydrolysis step. Asparagine is determined as aspartic acid and glutamine as glutamic acid. Cystine and cysteine are converted to S-2-carboxyethylthiocysteine (CYSx) and the derivative is separated from the other amino acids. Citrulline, which is present in some matrixes, is separated from other amino acids and is not included in the method performance evaluation in the single-laboratory validation (SLV). The proposed method met all the performance requirement limits set in Standard Method Performance Requirement (SMPR®) 2014.013 for total proteinogenic amino acids and taurine. The correlation coefficient of multi-point calibration was not less than 0.999 for any amino acids at any point in the SLV study, confirming the validity of linear dynamic range (LDR) and linearity of the method. The individual amino acids in the chromatogram were identified by absolute retention time and relative retention time (RRT) with respect to the internal standard norvaline. There were no significant (S/N <10) interferences from the reagents or byproducts of derivatization and targeted matrixes. The method demonstrated high selectivity. Accuracy of the method was validated using standard reference materials (SRMs; NIST SRM 1869 and 1849a) and spike recovery studies. The amino acid results in the SRMs were within the ranges of Reference Mass Fraction Values. The accuracy of the method was corroboratively validated by spike recovery studies. The average spike recovery ranged between 93 and 107% ensuring the accuracy of the method for amino acids and compliance with AOAC SMPR 2014.013. Precision data of the method demonstrate that it meets the stakeholder requirements as per the SMPR. The mean RSDr for all the amino acids for 17 matrixes selected for the SLV were not more than 4%. The method is very sensitive and the LOQ can go down to approximately ten times lower than the SMPR requirements. The sensitivity of method is a direct reflection of its signal-to-noise ratio which ensures guaranteed method performance at the lower levels of amino acids in these matrixes. Taurine (aminoethane sulfonic acid), unlike the other amino acids, is a beta-sulfonic amino acid that is not used in protein synthesis but is found as a free amino acid in tissues. The acidic functional group (-COOH) in common amino acids is replaced with a sulfonic acid (-SO3H) group in taurine. The method offers baseline separation of citrulline which is an alpha amino acid generally present in infant formula and adult/pediatric nutritional products. The separation of citrulline eliminates the risk of interference of this compound with other amino acids. The method can also separate and quantitate hydroxyproline, an important component of collagen that is often used to quantitate collagen. The method is simple and does not include any proprietary chemicals or instruments, and it can be performed on any basic reverse phase UHPLC system with UV detection (1-6).

Aminoethanesulfonic Acid- Based Blends for Inhibition of J55 Steel Corrosion in Simulated Oilfield Pickling Fluid

Aminoethanesulfonic Acid- Based Blends for Inhibition of J55 Steel Corrosion in Simulated Oilfield Pickling Fluid

Integrating cationic metal-organic frameworks with ultrafiltration membrane for selective removal of perchlorate from Water

We design a novel cationic metal-organic framework hybrid ultrafiltration polyvinylidene fluoride membrane (PVA/Cu-iMOFs/PVDF-0.05) and report its unique capture of aqueous perchlorate (ClO4−) at ppm-level. This membrane outperformed traditional adsorption materials and exhibited a specific affinity toward ClO4− in the presence of various competing anions at greater levels (up to a concentration ratio of 20). In the batch experiment, the ClO4− removal ratio reached 99.6% over a wide pH range (3˜10). Membrane filtration by using a 12.56 cm2 PVA/Cu-iMOFs/PVDF-0.05 membrane could effectively treat 4.71 L of ClO4−-contaminated water before breakthrough occurred, while maintaining a satisfactory permeability (˜627.32 L/(m2 h bar)) and antifouling property. The exhausted membrane could easily be regenerated in aminoethanesulfonic acid solution for repeated use with a negligible decrease in capacity. Moreover, the membrane showed excellent long-term stability in a cross-flow filtration process due to the amido bond between the Cu-iMOFs and membrane surface as well as the "protection" of polyvinyl alcohol. Selective and reversible ion-exchange between the sulfonic acid (R-SO3) ligands of Cu-iMOFs and tetrahedral oxo-anionic species was verified to be the pathway for ClO4− trapping. Thus, other problematic elements that also occur in tetrahedral form in water can be removed by this method.

Synthesis of Conjugates of Lupane-Type Pentacyclic Triterpenoids with 2-Aminoethane- and N-Methyl-2-Aminoethanesulfonic Acids. Assessment of in vitro Toxicity

Conjugates of betulin and betulinic and betulonic acids with 2-aminoethane- and N-methyl-2-aminoethanesulfonic acids were synthesized for the first time and were interesting as potential biologically active compounds. Experiments in vitro in MDCK cell culture using the MTT assay found that betulin and betulinic-acid derivatives with aminoethanesulfonic acid bound to triterpene C-3 or C-28 through an ester linker were less toxic than the native compounds.

Calorimetric investigation of copper binding in the N-terminal region of the prion protein at low copper loading: evidence for an entropically favorable first binding event.

Although the Cu2+-binding sites of the prion protein have been well studied when the protein is fully saturated by Cu2+, the Cu2+-loading mechanism is just beginning to come into view. Because the Cu2+-binding modes at low and intermediate Cu2+ occupancy necessarily represent the highest-affinity binding modes, these are very likely populated under physiological conditions, and it is thus essential to characterize them in order to understand better the biological function of copper–prion interactions. Besides binding-affinity data, almost no other thermodynamic parameters (e.g., ΔH and ΔS) have been measured, thus leaving undetermined the enthalpic and entropic factors that govern the free energy of Cu2+ binding to the prion protein. In this study, isothermal titration calorimetry (ITC) was used to quantify the thermodynamic parameters (K, ΔG, ΔH, and TΔS) of Cu2+ binding to a peptide, PrP(23–28, 57–98), that encompasses the majority of the residues implicated in Cu2+ binding by full-length PrP. Use of the buffer N-(2-acetomido)-aminoethanesulfonic acid (ACES), which is also a well-characterized Cu2+ chelator, allowed for the isolation of the two highest affinity binding events. Circular dichroism spectroscopy was used to characterize the different binding modes as a function of added Cu2+. The Kd values determined by ITC, 7 and 380 nM, are well in line with those reported by others. The first binding event benefits significantly from a positive entropy, whereas the second binding event is enthalpically driven. The thermodynamic values associated with Cu2+ binding by the Aβ peptide, which is implicated in Alzheimer’s disease, bear striking parallels to those found here for the prion protein.

Synthesis, characterization and structures of copper(II) complexes containing carboxylate and sulfonate groups

Four copper(II) complexes containing Schiff base and reduced Schiff base ligands derived from pyridine-2-aldehyde and amino acid containing carboxylate and sulfonate functional groups (N-(2-pyridylmethylene)-amino acid and N-(2-pyridylmethyl)-amino acid, (amino acids = β-alanine and aminoethanesulfonic acid) namely, [Cu(Pbals)(H2O)2]ClO4·H2O 1, [Cu(Pbal)(ClO4)(H2O)] 2, [Cu2(Paes)2(ClO4)2]·2H2O 3, and [Cu(Pae)(H2O)]·ClO4·H2O 4 have been synthesized and characterized. The structural features of carboxylate and sulfonate donor groups have been elucidated. These copper(II) complexes demonstrate different coordination behaviour of the carboxylate and sulfonate groups. Carboxylate groups in complexes 1 and 2 bridge the metal centers and facilitate the formation of 1D helical coordination polymeric structures. In compound 3, the sulfonate groups bridge the metal centers to form a discrete dinuclear complex. In 4, the sulfonate groups link the neighbouring metal centers to form a 1D coordination polymeric structure.

Physiological roles of taurine in heart and muscle

Taurine (aminoethane sulfonic acid) is an ubiquitous compound, found in very high concentrations in heart and muscle. Although taurine is classified as an amino acid, it does not participate in peptide bond formation. Nonetheless, the amino group of taurine is involved in a number of important conjugation reactions as well as in the scavenging of hypochlorous acid. Because taurine is a fairly inert compound, it is an ideal modulator of basic processes, such as osmotic pressure, cation homeostasis, enzyme activity, receptor regulation, cell development and cell signalling. The present review discusses several physiological functions of taurine. First, the observation that taurine depletion leads to the development of a cardiomyopathy indicates a role for taurine in the maintenance of normal contractile function. Evidence is provided that this function of taurine is mediated by changes in the activity of key Ca2+ transporters and the modulation Ca2+ sensitivity of the myofibrils. Second, in some species, taurine is an established osmoregulator, however, in mammalian heart the osmoregulatory function of taurine has recently been questioned. Third, taurine functions as an indirect regulator of oxidative stress. Although this action of taurine has been widely discussed, its mechanism of action is unclear. A potential mechanism for the antioxidant activity of taurine is discussed. Fourth, taurine stabilizes membranes through direct interactions with phospholipids. However, its inhibition of the enzyme, phospholipid N-methyltransferase, alters the phosphatidylcholine and phosphatidylethanolamine content of membranes, which in turn affects the function of key proteins within the membrane. Finally, taurine serves as a modulator of protein kinases and phosphatases within the cardiomyocyte. The mechanism of this action has not been studied. Taurine is a chemically simple compound, but it has profound effects on cells. This has led to the suggestion that taurine is an essential or semi-essential nutrient for many mammals.

Synthesis and antiarrhythmic activity of n-(1-methyl-2-phenylethyl)aminoethanesulfonic acid isopropylamide hydrochloride

The synthesis and pharmacological properties of a new taurine amide derivative, N-(l-methyl-2-phenylethyl) aminoethanesulfonic acid isopropylamide hydrochloride (I), are described. Pronounced antiarrhythmic effect of compound I was observed in animals with experimental ventricular arrhythmias (early postocclusive and calcium chloride models). The drug significantly decreased the frequency and intensity of paroxysmal tachycardia attacks and ventricular fibrillation after coronary artery occlusion. Simultaneous administration of calcium chloride and compound I increased the arrhythmogenic dose of calcium chloride, inducing lethal heartbeat disorder and asystolia, and decreased the frequency of ventricular flutter and fibrillation. The antiarrhythmic effect of the drug was similar to that of lidocaine. The antifibrillatory activity is the most important manifestation of the antiarrhythmic action of the taurine derivative studied. These data suggest that compound I is a potential drug for urgent aid in myocardial infarction.

Cerebroprotective effect of a new taurine derivative during cerebral ischemia

A new taurine derivative chlorohydrate-N-isopropylamide-2-(1-phenylethyl)aminoethanesulfonic acid normalized energy metabolism, inhibited lipid peroxidation, and reactivated antioxidant enzymes in the brain of rats exposed to ischemia. This taurine derivative decreased the mortality rate of animals with ischemic changes in cerebral circulation. The test compound was more potent than piracetam in producing the cerebroprotective effect.

Phyllodulcin, a constituent of "Amacha", inhibits phosphodiesterase in bovine adrenocortical cells.

Phyllodulcin, a constituent of "Amacha", inhibits phosphodiesterase in bovine adrenocortical cells.

Survival, fecundity and fertility of Bactrocera oleae, as affected by amino acid analogues

AbstractThe effect of twenty five amino acid analogues at various concentrations upon the adult olive fruit fly Bactrocera oleae Gmelin (Diptera: Tephritidae), was tested. Insect survival was significantly shortened by the following amino acid analogues: (in parentheses are indicated the antagonized amino acids) D‐cycloserine (alanine), L‐glutamic acid‐γ‐hydrazide (glutamine), DL‐allyl‐glycine (cysteine), L‐canavanine (arginine), L‐methionine‐DL‐sulfoximine (methionine) and 3,4‐dehydro‐DL‐proline (proline). Fecundity was significantly reduced by the same analogues plus aminoethanesulfonic acid (glycine), taurine (alanine), L‐norvaline (leucine), a‐methyl‐DL‐serine (serine), DL‐hydroxyglutamic acid (glutamic acid), (S)‐2‐(aminoethyl)‐L‐cysteine (lysine), a‐methyl‐DL‐methionine (methionine) and a‐methyl‐DL‐histidine (histidine). All the above amino acid analogues also depressed egg‐hatching with the exception of taurine, DL‐hydroxyglutamic acid, DL‐allyl glycine, a‐methyl‐DL‐methionine and a‐methyl‐DL‐histidine. Finally, y‐glutamyl‐p‐nitroanilide (glutamic acid), crotyl‐glycine (methionine), DL‐7‐azatryptophan and 5‐methyl‐DL‐tryptophan (tryptophan), DL‐1,2,4 triazole‐3‐alanine (histidine) and DL‐pipecolic acid (proline) did not affect any of the parameters tested.

Inhibitors of anion exchanger activity reduce sodium chloride-dependent taurine transport by brush border vesicles.

The erythrocyte anion exchanger, or band 3 protein, catalyzes the exchange of chloride and bicarbonate in many cells. Anion exchanger activity is predominantly found in the basolateral membrane of the cortical collecting duct. Because proximal tubular renal taurine uptake across the brush border surface is dependent upon sodium and chloride, the effect of inhibitors of anion exchanger activity on renal taurine accumulation by rat renal brush border membrane vesicles was examined. The anion exchanger probes, DIDS (4,4-'diisothiosulfonic acid), and NBD-taurine (N-[7-nitrobenz-2-oxa-1,3-diazol-4-yl]-aminoethane sulfonic acid), and NBD-taurine (N-[7-nitrobenz-2-oxa-1,3-diazol-4-yl]-aminoethane sulfonic acid), were used as inhibitors of anion exchanger activity. DIDS, NAP-, and NBD-taurine all markedly inhibit the initial rate of NaCl-dependent accumulation of taurine by brush border membrane vesicles. NAP- and NBD-taurine accumulation is chloride dependent because inhibition was not found when uptake was performed in the presence of NaNO3 in place of chloride. In the presence of maximal inhibition of taurine uptake by NAP- or NBD-taurine, no additional inhibition was evident after incubation with DIDS. On the other hand, when a competitive inhibitor of taurine uptake, beta-alanine, was used, additional inhibition of taurine accumulation was found in the presence of NAP- or NBD-taurine (p < .01 respectively). These results suggest some interaction of the anion exchanger and the taurine accumulation process at the apical surface of the proximal tubule. Because NBD-taurine is a fluorescent probe, it may be possible to isolate membrane peptides that bind NBD-taurine and demonstrate fluorescence. Preliminary isoelectric focusing experiments of brush border protein incubated with NBD-taurine show fluorescence localized to several particular fractions. Hence this observation that inhibitors of the anion exchanger system block NaCl-dependent taurine uptake can potentially serve as a means of isolating the taurine transporter protein.