N-lauroylsarcosine Sodium Research Articles

Two-staged sorption isotherm of a nanoporous energy absorption system

To selectively absorb impact energy, the profiles of sorption isotherms of protection systems must be adjusted in a broad spectrum. In this article, a N-Lauroylsarcosine sodium salt (sarcosyl) of intermediate molecular size is used to control the pressure induced infiltration of a nanoporous silica. The experimental result shows that the infiltration plateau of this system is two-staged; that is, not only the activation pressure but also the infiltration volume can be modified. It is noticed that the sarcosyl molecule demands a “free volume” to enter a nanopore. The free volume size decreases nearly linearly as the sarcosyl concentration increases.

Synergistic fungicidal activity of Cu 2+ and allicin, an allyl sulfur compound from garlic, and its relation to the role of alkyl hydroperoxide reductase 1 as a cell surface defense in Saccharomyces cerevisiae

Cu 2+ showed a dose-dependent fungicidal activity against Saccharomyces cerevisiae cells, and its lethal effect was extremely enhanced in the presence of allicin, an allyl sulfur compound from garlic. The fungicidal activity of Cu 2+ was unaffected or rather attenuated by other sulfur-containing compounds such as N-acetyl-cysteine, l-cysteine or dithiothreitol. Ca 2+ could absolutely protect against the lethal effect of Cu 2+ itself, but showed no protection against the fungicidal activity of Cu 2+ newly generated in combination with allicin. Cu 2+ accelerated an endogenous generation of reactive oxygen species (ROS) in S. cerevisiae cells at a lethal concentration, but such intracellular oxidative stress induction was not observed during cell death progression upon treatment with Cu 2+ and allicin. A surfactant, sodium N-lauroyl sarcosinate (SLS), enhanced the solubilization of a few proteins including alkyl hydroperoxide reductase 1 (AHP1) in intact cells, accounting for the absence of this protein in the extract from allicin-treated cells. Allicin-treated cells were rendered extremely sensitive to the subsequent Cu 2+ treatment as in the case of SLS-treated cells. Allicin-treated cells and SLS-treated cells similarly showed an increased sensitivity to exogenously added tert-butyl hydroperoxide ( t-BOOH), an organic peroxide that is detoxified by the action of AHP1. Our study suggests that allicin influences the mode of cell surface localization or the related function of AHP1 as a defense against phospholipid peroxidation by the external action of Cu 2+.

CDNA Cloning and Expression of the Cardiac Na+/Ca2+ Exchanger from Mozambique Tilapia (Oreochromis mossambicus) Reveal a Teleost Membrane Transporter with Mammalian Temperature Dependence

The complete cDNA sequence of the tilapia cardiac Na(+)/Ca2+ exchanger (NCX-TL1.0) was determined. The 3.1-kb transcript encodes a protein 957 amino acids in length, with a predicted signal peptide cleaved at residue 31 and two potential N-glycosylation sites in the extracellular N terminus. Hydropathy analysis and sequence comparison predicted a mature protein with nine transmembrane-spanning segments, consistent with the structural topologies of other known mammalian and teleost NCX isoforms. Overall sequence comparison shows high identity to both trout NCX-TR1.0 ( approximately 81%) and mammalian NCX1.1 ( approximately 73%), and phylogenetic analyses confirmed its identity as a member of the NCX1 gene family, expressing exons A, C, D, and F in the alternative splice site. Sequence identity is even higher in the alpha-repeats, the exchanger inhibitory peptide (XIP) site, and Ca(2+)-binding domains, which is reflected in the functional and regulatory properties of tilapia NCX-TL1.0. When NCX-TL1.0 was expressed in Xenopus oocytes and the currents were measured in giant excised patches, they displayed both positive regulation by Ca2+ and Na(+)-dependent inactivation in a manner similar to trout NCX-TR1.0. However, tilapia NCX-TL1.0 exhibited a relatively high sensitivity to temperature compared with trout NCX-TR1.0. Whereas trout NCX-TR1.0 currents displayed activation energies of approximately 7 kJ/mol, tilapia NCX-TL1.0 currents showed mammal-like temperature dependence, with peak and steady-state current activation energies of 53 +/- 9 and 67 +/- 21 kJ/mol, respectively. Using comparative sequence analysis, we highlighted 10 residue positions in the N-terminal domain of the NCX that, in combination, may confer exchanger temperature dependence through subtle changes in protein flexibility. Tilapia NCX-TL1.0 represents the first non-mammalian NCX to exhibit a mammalian temperature dependence phenotype and will prove to be a useful model in defining the interplay between molecular flexibility and stability in NCX function.

Sensitivity to detergents and plasmid curing in Enterococcus faecalis

This research reports the sensitivity of a clinical isolate of Enterococcus faecalis to sodium N-lauroylsarcosinate (sarkosyl) and sodium dodecyl sulfate (SDS), as well as the efficiency of these detergents in curing the strain. Compared to Escherichia coli, Enterococcus faecalis was very sensitive to both detergents, with minimum inhibitory concentrations (MIC) for the latter being 100 times lower than for Escherichia coli. The clinical isolate of Enterococcus faecalis used in this study exhibited plasmid-borne resistance to kanamycin (MIC 2 mg/ml) and tetracycline (MIC 50 mug/ml); 3% curing was observed after growth in the presence of sarkosyl but no curing was observed after growth in the presence of either SDS or acridine orange. In contrast, 35% curing of plasmid-bearing Escherichia coli was observed after growth in the presence of either SDS or acridine orange, but none was observed after growth in the presence of sarkosyl.

Pitting inhibition of stainless steel by surfactants: an electrochemical and surface chemical approach

Pitting corrosion of stainless steels causes tremendous damage in terms of material loss and resulting accidents. Organic surfactants have been tried as pitting inhibitors but the understanding of the inhibition mechanisms is mainly speculative. In the present study the inhibition of the pitting corrosion of 304 stainless steel by N-lauroylsarcosine sodium salt (NLS) in 0.1 M NaCl solutions at neutral pH was studied using an approach that combines surface chemical techniques with electrochemical ones. It was found that NLS increases the pitting resistance of 304 stainless steel, with possible complete inhibition at high NLS concentration (30 mM). Adsorption of NLS on 304 stainless steel particles was directly measured. NLS adsorbs significantly on 304 stainless steel with maximum adsorption density close to bilayer coverage. Electrophoretic mobility data for 304 stainless steel particles show that the surface of 304 stainless steel is negative in NaCl solution at neutral pH. The adsorption of NLS makes the interfacial charge even more negative. The relationship between pitting inhibition and adsorption density of NLS suggests that NLS does not adsorb preferentially on the pit nucleation sites and complete inhibition requires that the whole surface be covered completely by NLS. The inhibition mechanism of NLS is proposed to be due mainly to the blocking effect of a negatively charged NLS adsorption layer. This study shows that in addition to the adsorption amount of surfactant, interfacial charge also plays an important role in pitting inhibition.

Purification and characterization of the major lipoprotein (P28) of Spiroplasma apis.

The plasma membrane of Spiroplasma apis contains a 28-kDa major protein (P28), like other spiroplasmas which also possess a main 26- to 28-kDa membrane polypeptide, called spiralin. In the work described here, we have developed a simple and efficient method for the purification of P28 of this mollicute, a wall-less eubacteria. Proteins were first selectively extracted from the isolated membrane with the mild detergents (i) sodium N-lauroylsarcosinate (Sarkosyl) and (ii) 3-[(3-cholamidopropyl)dimethylamonio]-1-propyl sulfonate (Chaps) and subjected to size-exclusion HPLC in the presence of Chaps. The P28-enriched fraction was thereafter subjected to the second chromatographic step involving cation exchange HPLC in the presence of the same detergent. P28 was purified at the milligram level (yield, 40%). Metabolite labeling with [14C]palmitic acid and chemical analysis of P28 indicated that it is covalently modified by two O-ester-bound fatty acids and one amide-linked chain and contains a S-glycerylcysteine at the N-terminus. By charge-shift electrophoresis, Triton X-114 phase separation, and growth inhibition tests it was shown that P28 is a typical amphiphilic protein exposed, at least partly, at the cell surface. Together, our data provided evidence that P28 is a "classical" lipoprotein (i.e., triacylated) like the members of the spiralin family.

Metallomicellar Catalysis: Catalytic Cleavage of p-Nitrophenyl Picolinate by Cu2+ Complex of 4-Chloride-2,6-bis(N-hydroxyethylaminomethyl)-benzophenol in Micellar Solution

The hydrolysis of p-nitrophenyl picolinate (PNPP) catalyzed by the Cu(II) complex of 4-chloride-2,6-bis(N-hydroxyethylaminomethyl)-benzophenol was investigated kinetically by observing the rates of release of p-nitrophenol in the presence of three surfactants, which are hexadecyltrimethylammonium bromide, n-lauroylsarcosine sodium, and polyoxyethylene(23) lauryl ether, at different pH and 25°C. The scheme for the reaction involving a ternary complex comprising ligand, metal ion, and substrate in a micelle was established, and the relative kinetic and thermodynamic parameters were determined, including first-order rate constant (kN), association constant (Ks) for ternary complex, and pKa for the hydroxide ion of the ternary complex. The reaction mechanism was discussed.

Characterization of chemical selectivity in micellar electrokinetic chromatography: V. The effect of the surfactant hydrophobic chain

The influence of the surfactant hydrophobic chain on selectivity in micellar electrokinetic chromatography was investigated using two sets of surfactants. A series of three sarcosinate surfactants (sodium N-lauroyl sarcosinate, sodium n−myristoyl sarcosinate, and sodium N-parmitoyl sarcosinate) with C11, C13, and C15 hydrocarbon tails were compared. In addition, sodium dodecyl sulfate and sodium tetradecyl sulfate were investigated to determine the chain length effect for sodium sulfate surfactants. Linear solvation energy relationships as well as free energy of transfer studies were used to predict the selectivity differences. The results suggest that although the surfactant chain length can have some effect, the magnitude of this influence seems to be dependent on the head group. © 2000 John Wiley & Sons, Inc. J Micro Sep 12: 433–441, 2000

Immunization of Cows with Ferric Enterobactin Receptor from Coliform Bacteria

The serum and milk immunoglobulin (Ig) G responses of lactating dairy cows were determined following immunization with ferric enterobactin receptor FepA. Escherichia coli 471 was cultured in iron-depleted medium, and outer membrane proteins were extracted by 2% N-lauroylsarcosine sodium salt and 2% Triton X-100. The FepA was isolated from the outer membrane proteins by ion-exchange chromatography. Twenty cows were assigned to four treatment groups of 5 cows blocked by breed and days in milk. Treatment groups were vaccinated with 100μg of FepA, 500μg of FepA, Escherichia coli J5 bacterin, or sterile phosphate-buffered saline. Primary immunization was at approximately 200 d in milk, and booster immunizations were given 14 and 28 d later. Serum and whey IgG titers to FepA in cows vaccinated with FepA were significantly higher than those from cows vaccinated with either E. coli J5 bacterin or phosphate-buffered saline. Serum and whey IgG titers to FepA were elevated by 14 d in cows vaccinated with FepA. Significant differences were not observed between doses of FepA. The degree of cross-reactivity of purified IgG from cows vaccinated with FepA to E. coli and Klebsiella pneumoniae isolates was significantly higher than that to a control isolate that lacked FepA production. Immunization with FepA elicited an immunological response in serum and milk.

The contribution of cytotoxicity to DNA-effects in the single cell gel test (comet assay)

We evaluated genotoxic and cytotoxic effects of the three non-mutagenic and non-carcinogenic compounds p-nitrophenol, d-menthol and sodium N-lauroyl sarcosine which have previously been shown to induce DNA double strand breaks (DNA dsb) secondary to induced cytotoxicity. We tested wheter genotoxic effects in the alkaline single cell gel test (comet assay) may be confounded by cytotoxicity-induced DNA dsb. Cell viability was determined at the end of the treatment using the fluorescein diacetate/ethidium bromide-assay and plating efficiency was used as an indicator of long-term survivability. Experiments with V79 Chinese hamster cells and human white blood cells revealed negative results in the comet assay despite strong cytotoxic effects. However, cells with extremely fragmented DNA (‘clouds’) occured but were excluded from the evaluation under the principle that they represent dead cells. We also noticed a significant loss of cells at cytotoxic concentrations that might be attributed to the induction of highly fragmented DNA which is lost during electrophoresis. Since the comet assay allows the determination of DNA effects on the single cell level, a confounding effect of cytotoxicity on test results can be avoided.

N-Lauroyl Sarcosine Sodium Salt as a Corrosion Inhibitor for Type 1518 Carbon Steel in Neutral Saline Environments

The influence of the sodium salt of N-lauroyl sarcosine (NLS) on corrosion of a manganese steel was studied in aerated, nearly neutral saline solutions at room temperature and under various hydrodynamic conditions. The inhibitive efficiency of NLS was examined using gravimetric tests, polarization curves, and electrochemical impedance spectroscopy (EIS). The additive slowed the corrosion phenomena, either generalized or localized, that occurred on steel, but only at the high rotation speed of the rotating cylinder electrode (RCE). The mechanism of action was anodic and probably resulted from precipitation of an insoluble product on the anodic areas.

Rapid dissolution of vitamin E by using sodium N-lauroylsarcosinate ionic surfactant

Vitamin E is widely used in pharmaceutical, food and cosmetic preparations. This paper discusses methods of preparing a vitamin E emulsion by using sodium N-lauroylsarcosinate (SNLS) ionic surfactant. The amount of vitamin E dissolved in water was analyzed by turbidity and UV absorption measurements. The emulsion droplet size was determined by laser light scattering. Microemulsions with small particle size and high resistance to oxidation in air can be obtained by solubilizing vitamin E in SNLS solution. The dissolution is rapid and the surfactant solution has high solubilization power. At 0.7% surfactant concentration, the saturation value is 1 g vitamin E per gram of surfactant. The micellar dissociation concentration (MDC) of the surfactant can be estimated from a vitamin saturation—surfactant concentration curve. Dissolution mechanisms at different surfactant concentrations are interpreted by use of the MDC and CMC (critical micellar concentration) concepts.

Characterization of a serum factor that decreases albumin mRNA in cultured hepatocytes.

When primary cultures of hepatocytes are exposed to media containing fetal bovine serum (FBS) there is a rapid decrease in levels of tissue-specific mRNAs such as albumin mRNA. We used Northern blot analysis to examine mRNA levels in cultured hepatocytes, and characterized the factor in FBS that significantly reduces the steady state albumin mRNA level. Neonatal bovine serum or serum derived from platelet-poor calf plasma proved as potent as did FBS, but commercial bovine serum albumin did not exhibit this inhibitory activity. Inhibitory activity of FBS was not removed by moderate heat treatment, dialysis, or extraction with organic solvents. However, incubation of FBS with a highly anionic detergent such as 0.1% sodium dodecyl sulfate or N-lauroyl sarcosine, followed by extensive dialysis, resulted in sera that did not inhibit expression of albumin mRNA. These sera supported cell attachment and seemed non-toxic toward the cells. Ammonium sulfate fractionation of FBS showed the activity was present in the 45 to 70% fraction, and trypsin digestion destroyed the inhibitory activity. Gel exclusion chromatography gave a molecular weight of 60,000 to 70,000. Fractionation of serum proteins by DEAE-Sephacel or Cibacron blue-agarose showed enrichment for albumin in the most active fractions. Interestingly, metabolic labeling of secreted and cellular proteins with 35S-methionine and cysteine showed no significant difference between hepatocytes maintained for 2 days beforehand in serum-free or serum-supplemented media, and no difference between detergent-treated FBS and control FBS.(ABSTRACT TRUNCATED AT 250 WORDS)

Drug-excipient interactions resulting from powder mixing. VI. Role of various surfactants

The role of various surfactants on the drug-excipient interactions resulting from prolonged powder mixing with magnesium stearate was investigated. Drug-excipient formulations containing 0.5% magnesium stearate and 0.1–0.5% surfactants were compared with the same formulations without the surfactant under identical mixing conditions to study the effect of prolonged mixing on the in vitro dissolution of ketorolac tromethamine from hand-filled, uncompacted capsules. The results indicate that some surfactants in a concentration as little as 0.1% (1:5 w/w ratio to magnesium stearate) can alleviate the deleterious effect of magnesium stearate on the prolonged mixing of powder, i.e., the decrease in the dissolution rate of the drug. The effectiveness of the surfactants is determined by their hydrophilic-lipophilic balance (HLB) value and solubility, and increases with increasing concentration or decreasing particle size. The hydrophilic anionic surfactants (sodium N-lauroyl sarcosinate, sodium stearoyl-2-lactylate, and sodium stearate), non-ionic surfactant (poloxamer 188), and cationic surfactant (cetylpyridinium chloride) are as effective as sodium lauryl sulfate reported in a previous study. Conversely, the lipophilic surfactant, glyceryl monostearate, failed to offset the deleterious effect of magnesium stearate. The results suggest that surfactant alone does not affect drug dissolution, but that it interacts with magnesium stearate during powder mixing. This interaction would reduce the net surface coverage of the drug-excipients by magnesium stearate. Furthermore, the water-soluble hydrophilic surfactant would help to detach any magnesium stearate film covering the drug-excipients, thus alleviating the decrease in drug dissolution caused by magnesium stearate. On the other hand, lipophilic surfactant is not soluble and ineffective despite its interaction with magnesium stearate.

Analytical procedures for a cryptic messenger RNA that mediates translational control of prostaglandin synthase by glucocorticoids

Expression of the enzyme prostaglandin H synthase in cultured vascular smooth muscle cells required epidermal growth factor (EGF) and type β transforming growth factor (TGF-β) and was inhibited by cycloheximide but not actinomycin D. Preincubation with the glucocorticoid dexamethasone (0.5 μ m) blocked the EGF-induced expression of prostaglandin H (PGH) synthase. Following dexamethasone addition, levels of hybridizable mRNA for PG synthase were reduced by over 90% within 1 h. After dexamethasone was removed, PG synthase mRNA recovered within 3 h by a process that was not inhibited by actinomycin D. These observations, together with other findings, suggested that the mRNA was being converted into some nonextractable and nontranslated form, probably by binding of a glucocorticoid-induced protein to the conserved 3′ untranslated region. In order to investigate further the nature of this phenomenon, seven different literature procedures were evaluated for extracting and determining the PG synthase mRNA. Five of the seven procedures failed to detect hybridizable PG synthase mRNA in glucocorticoid-treated cells. Two procedures, however, recovered mRNA in both glucocorticoid-treated and control cells. A comparison of the protocols indicated that only those methods that incorporate a cationic detergent (sodium N-lauroylsarcosine), instead of anionic detergents in the lysis or homogenization buffers, successfully extract the glucocorticoid-suppressed PG synthase mRNA. Based upon these results two procedures are described, one that optimizes the extraction and determination of the glucocorticoid-suppressed (cryptic) form of the mRNA, and another which optimizes the analysis of normal mRNA without extracting the cryptic form. The results indicate that translational control of PG synthase by glucocorticoids is regulated by converting the mRNA into a cryptic form that is more firmly tissue bound than normal mRNA.

Outer membrane protein profiles of Yersinia ruckeri

The outer membrane protein (OMP) profiles of 135 isolates of Yersinia ruckeri, obtained from nine European countries (100 isolates), North America (23 isolates), Australia) (six isolates) and South Africa (two isolates), and including four reference strains, were examined by SDS-PAGE. Outer membranes were isolated by selective solubilisation of the cytoplasmic membrane with 0.5% ( w/ v) sodium N-lauroyl sarcosinate (Sarkosyl). Outer membrane proteins were stable after in vitro passage and there was no variation in OMP profiles due to colony selection. With the exception of a 39.5 kDa peptidoglycan-associated protein there was no variation at different stages of the growth cycle. The 39.5 kDa protein was not produced during logarithmic growth phase but increased in abundances as the stationary phase progressed. Interstrain variation occurredin the possession on a 36.5 or 38 kDa heat-modifiable protein and in the possession of peptiddoglycan-associated proteins in the molecular weight range 36.5 to 40.5 kDa. Based on variation of these proteins five OMP-types, designated OMP-types 1–5, were identified among the 135 isolates examined. Outer membrane protein analysis was demonstrated to be useful in epidemiological studies of Y. ruckeri.

Solubilization of the 97-kDa native form of liver microsomal 3-hydroxy-3-methylglutaryl-coenzyme A reductase.

Liver microsomal 3-hydroxy-3-methylglutaryl-CoA reductase was partially purified from cholestyramine-fed rats by sequential extraction of the membrane with 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS) and polyethylene glycol nonylphenyl ether (Triton N-101) and solubilized by incorporation of the resulting insoluble protein preparation into a detergent mixture of Triton N-101 and sodium N-lauroylsarcosinate (Sarkosyl) in the presence of high salt. The purification procedure resulted in approximately a 3-4-fold increase in specific activity compared with the microsomal fraction, and the enzyme was recovered with yields as high as 63%. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and a blotting experiment using antiserum to the purified 53,000-dalton reductase fragment showed that the major immunoreactive polypeptide had a Mr of 97,000, that expected for the native intact form of the enzyme (Chin, D. J., Gil, G., Russell, D. W., Liscum, L., Luskey, K. L., Basu, S. K., Okayama, H., Berg, P., Goldstein, J. L., and Brown, M. S. (1984) Nature 308, 613-617). In addition, the effect of various detergents on the activity and stability of the membrane-bound and the partially purified enzyme was determined, and a method for protection of the reductase from inactivation caused by the addition of anionic detergents to the assay mixture is described.

Synthesis of a select group of proteins by Neisseria gonorrhoeae in response to thermal stress

We report the thermal conditions that induce the heat shock response in Neisseria gonorrhoeae. Under conditions of thermal stress, Neisseria gonorrhoeae synthesizes heat shock proteins (hsps), which differ quantitatively from conventionally studied gonococcal proteins. Gonococci accelerate the rate of synthesis of the hsps as early as 5 min after the appropriate stimulus is applied, with synthesis continuing for 30 min, as demonstrated by in vivo labeling experiments with L-[35S]methionine. Two of the gonococcal hsps are immunologically cross-reactive with the hsps of Escherichia coli, DnaK and GroEL, as demonstrated by Western blot (immunoblot) analysis. Ten hsps can be identified on two-dimensional autoradiograms of whole gonococci (total protein). Four hsps can be identified on two-dimensional autoradiograms of 1% N-lauroylsarcosine (sodium salt) (Sarkosyl)-insoluble membrane fractions. Two of the hsps from the 1% Sarkosyl-insoluble fraction are found exclusively in this fraction, suggesting that they are membrane proteins. The identification of this group of proteins will facilitate further study of the function of these proteins and provide insight into the possible role of hsps in disease pathogenesis.

Zero-Order and Third-Derivative Spectrophotometric Determination of Iron(III) with 4-(2-Pyridylazo)-Resorcinol in the Presence of N-Hexadecylpyridinium Chloride

Abstract The complex formation reaction between iron(III) and 4-(2-pyridylazo) resorcinol(PAR) in the presence of various water soluble surfactants((N-hexadecylpyridinium chloride (HPC), poly(vinylalcohol)(PVA), sodium dodecylsulfate(SDS), sodium N-lauroylsarcosine(SL)) alone or in combination at weakly acidic media was systematically investigated. An improved and more sensitive spectrophotometric method for the determination of iron was proposed by zero-order and third-derivative spectrophotometry using the PAR-iron(III)-HPC ternary complex system at about pH 5.2. The calibration curve was rectilinear in the ranges of 0 – 15.0 μg iron(III) in a final 10-ml on the zero-order spectrophotometry. Also, upon the third-derivative spectrophotometry, Beer's law was obeyed in the range of 0 – 8.0 μg iron(III)/10 ml by measuring the distance between the absorbance peak(λ1 = 527 nm) and the valley (λ2 = 560 nm). The apparent molar absorptivity was 4.8 × 104 1 mol−1 cm−1 in zero-order spectrophotometry, and 1.36 × 105 mol−1 cm−1 in third-derivative spectrophotometry. The effect of foreign ions was decreased within ½ – ¼-fold in comparison with the method in the presence of PVA without HPC. Especially, the third-derivative spectrophotometric method was sensitive and selective, and made possible to assay mixed sample solution containing iron(III) and copper(II), etc.

Immunobiological activities of a porin fraction isolated from Fusobacterium nucleatum ATCC 10953.

From Fusobacterium nucleatum ATCC 10953 cell envelope fraction whose inner membranes had been removed by treatment with sodium N-lauroyl sarcosinate, an outer membrane protein (37,000 Mr in a native state) was prepared by extraction with lithium dodecyl sulfate. The protein thus obtained showed distinct porin activity, namely, the ability to form hydrophilic diffusion pores by incorporation into the artificial liposome membrane. The porin fraction exhibited strong immunobiological activities in the in vitro assays: B-cell mitogenicity and polyclonal B-cell activation on murine splenocytes, stimulatory effects on guinea pig peritoneal macrophages, and enhancement of the migration of human blood monocytes. The porin fraction also exhibited immunoadjuvant activity to increase the antibody production against sheep erythrocytes in the spleen of mice that were immunized by sheep erythrocytes with porin. Although chemical analyses revealed that the test porin fraction contained a considerable amount of lipopolysaccharide (LPS) (around 12% of the fraction), the studies with LPS-nonresponding C3H/HeJ mice and on the inhibitory effects of polymyxin B strongly suggest that most of the above bioactivities are due to porin protein itself, not to coexistent LPS in the porin fraction.