Langmuir monolayer of artificial pulmonary surfactant mixtures with an amphiphilic peptide at the air/water interface: comparison of new preparations with surfacten (Surfactant TA).

Interfacial behavior was studied on the pulmonary lipid mixture containing a newly designed amphiphilic alpha-helical peptide (Hel 13-5) that consists of 13 hydrophobic and 5 hydrophilic amino acid residues. Moreover, the data obtained were compared with those of commercially available Surfacten (Surfactant TA) which has been clinically used for neonatal respiratory distress syndrome (NRDS) in Japan. Surface pressure (pi)-A and surface potential (DeltaV)-area (A) isotherms were measured for our synthetic preparations and Surfacten.

A review of recent studies on aqueous binary mixed surfactant systems.

Recent studies on mixed surfactant systems were systematically overviewed, paying special attention to synergism observed in micellization as well as adsorbed film formation upon mixing of a few nonionic surfactants with a variety of surfactants (such as anionics including bile salts and a hybrid type surfactant, cationics including a Gemini type surfactant, different types of nonionics and a zwitterionic surfactant used as a membrane solubilizer) in addition to various combinations of anionics. Through the text, it was shown for each given binary mixed system composed of surfactants 1 and 2 how to estimate not only the composition of mixed micelles (Y(2)) equilibrated with singly dispersed surfactant species in bulk solution phase, where the mole fraction of 2 in the surfactant mixture is denoted as X(2), but also the composition of adsorbed film phase (Z(2)). Almost all combinations were discussed in terms of the respective interaction parameters, omega(R) and omega(A), in mixed micelles (3-D phase) and in mixed adsorbed film (2-D phase), respectively, surface excess concentration (Gamma), partial molecular area (PMA), minimum surface Gibbs energy (G(s)min), and such defined measures as pC(20), CMC/C(20) etc.

Blending effects on adsorption and micellization of different membrane protein solubilizers II. A thermodynamic study on a mixed system of CHAPS with a bile salt in pH 7.4 phosphate buffer solution.

For a mixed system of a typical membrane protein solubilizer CHAPS (a derivative of a bile acid cholic acid) combined with a bile salt (sodium salt of glycocholic acid, NaGC), which is also a candidate as a membrane protein solubilizer, micellization and adsorbed film formation in a phosphate buffer solution of pH 7.4 at 303 K were studied paying special attention to the synergistic effect upon mixing. The collection of sufficient data based on plots of surface tension (gamma) versus logarithmic concentration (C(t) or m(t)) in total molality at discrete mole fractions (X(2)) in the mixture of surfactants 1 and 2 (where 1 and 2 correspond to CHAPS and NaGC, respectively) allowed us to accurately determine critical micelle concentration (CMC), minimum surface tension at CMC (gamma(CMC)), and the slope (dgamma/dlnC(t)) from the gamma-lnC(t) curves in the concentration range just below CMC.

Monolayers (Langmuir films) behavior of multi-component systems composed of a bile acid with different sterols and with their 1:1 mixtures.

Different physicochemical properties of Langmuir films (monolayers) composed of 10 mixed systems of a bile acid, deoxycholic acid (DC) with various plant sterols, such as stigmasterol (Stig), beta-sitosterol (Sito) and campesterol (Camp) and a stanol, cholestanol (Chsta) in addition to an animal sterol, cholesterol (Ch) [these sterols and Chsta are abbreviated as St] and DC with 1:1 St mixtures; (Ch+Chsta), (Ch+Stig), (Stig+Chsta), (Ch+Sito) and (Ch+Camp) on the substrate of 5M aqueous NaCl solution (pH 1.2) at 25 degrees C, were investigated in terms of mean surface area per molecule (A(m)), the partial molecular area (PMA), surface excess Gibbs energy (DeltaG((ex))), interaction parameter (I(p)) as well as activity coefficients (f(1) and f(2)) in 2-D phase of each binary (or ternary) component system and elasticity (Cs(-1)) of formed films; these were analyzed on the basis of the respective surface pressure (pi) versus A(m) isotherms as a function of mole fraction of Sts (X(st)) in the DC/St(s) mixtures at discrete surface pressures. Notable findings are: (i) all the binary component systems did form patched film type monolayers consisting of (a) DC-dominant film solubilizing a trace amount of St molecules and (b) St dominant film dissolving a small amount of DC molecules, (ii) DC in 2-D phase exhibited a transition from LE film to LC film at a constant pressure (pi(C)(1)) accompanied by compression and (iii) DeltaG((ex)) as well as I(p) was found to be greatly dependent on (a) the combinations of DC with different St species and (b) to be markedly varied by a difference in mixing ratio of DC to Sts.

On the adsorption properties of surface chemically pure CHAPS at the air/water interface.

CHAPS, a surface-active derivative of the steroids' basic structure of the cholic acid [3-[(3-cholamidopropyl)dimethyl-ammonio]-1-propanesulfonate] has become a very important material in biological and pharmaceutical application. Investigations of the adsorption properties of aqueous, surface-chemically pure CHAPS solutions at the air/water interface were performed using surface tension and surface potential measurements. Unlike ordinary extended-chain surfactants, the amphiphilic structure of CHAPS is prone to adopt different concentration-dependent surface states of the adsorption layer.

Mode of interaction of two fluorinated-hydrogenated hybrid amphiphiles with dipalmitoylphosphatidylcholine (DPPC) at the air-water interface.

Two-component Langmuir monolayers formed on 0.02 M Tris buffer solution (pH 7.4) with 0.

Mode of interaction of hydrophobic amphiphilic alpha-helical peptide/dipalmitoylphosphatidylcholine with phosphatidylglycerol or palmitic acid at the air-water interface.

Surface pressure (pi)-, surface potential (DeltaV)-, dipole moment (mu( perpendicular))-area (A) isotherms and morphological behavior at the air-water interface were obtained for multicomponent monolayers of two different systems for dipalmitoylphosphatidylcholine (DPPC)/egg-phosphatidylglycerol (PG) (= 68:22, by weight)/Hel 13-5 and DPPC/palmitic acid (PA) (= 90:9, by weight)/Hel 13-5 (Hel 13-5 is a newly designed 18-mer amphiphilic alpha-helical peptide with 13 hydrophobic and 5 hydrophilic amino acid residues). The phase behavior of these model systems was investigated on a subsolution of 0.02 M tris(hydroxymethyl)aminomethane (Tris) buffer (pH 8.

Mode of interaction of amphiphilic alpha-helical peptide with phosphatidylcholines at the air-water interface.

Surface pressure (pi)-, surface potential (deltaV)-, and dipole moment (mu(perpendicular))-area (A) isotherms and morphological behavior were examined for monolayers of a newly designed 18-mer amphiphilic alpha-helical peptide (Hel 13-5), DPPC, and DPPC/egg-PC (1:1) and their combinations by the Wilhelmy method, ionizing electrode method, fluorescence microscopy (FM), and atomic force microscopy (AFM). The newly designed Hel 13-5 showed rapid adsorption into the air-liquid interface to form interfacial films such as a SP-B function. Regardless of the composition and constituents in their multicomponent system of DPPC/egg-PC, the collapse pressure (pi(c); approximately 42 mN m(-1)) was constant, implying that Hel 13-5 with the fluid composition of egg-PC is squeezed out of Hel 13-5/DPPC/egg-PC monolayers accompanying a two- to three-dimensional phase transformation.

Langmuir monolayer properties of the fluorinated-hydrogenated hybrid amphiphiles with dipalmitoylphosphatidylcholine (DPPC).

Surface pressure-area (pi-A), surface potential-area (DeltaV-A), and dipole moment-area (mu( perpendicular)-A) isotherms were obtained for the Langmuir monolayer of two fluorinated-hydrogenated hybrid amphiphiles (sodium phenyl 1-[(4-perfluorohexyl)-phenyl]-1-hexylphosphate (F6PH5PPhNa) and (sodium phenyl 1-[(4-perfluorooctyl)-phenyl]-1-hexylphosphate (F8PH5PPhNa)), DPPC and their two-component systems at the air/water interface. Monolayers spread on 0.02 M Tris buffer solution (pH 7.

A kinetic and thermodynamic study on hydrolysis of sodium laurate in aqueous phase accompanied by transfer into oil phases containing different organic additives (I).

The kinetic and thermodynamic behavior at the interface between an aqueous solution of sodium laurate (NaLA) and various oil phases comprised primarily of benzene (Bz) and/or different organic compounds including amphiphiles has been investigated in regard to the hydrolysis of NaLA accelerated at the interface, transfer of lauric acid (LA) into oil phase and reverse transfer of Bz into aqueous phase in addition to interface tension. The contact of aqueous NaLA solution with the oil phase was found to accompany the mass transfer of LA and simultaneously promote the hydrolysis of NaLA in water phase. Analysis of the change of OH- ion concentration ([OH-]) over time allowed us to treat the events as a first order reaction.

Blending effects on adsorption and micellization of different membrane protein solubilizers: a thermodynamic study on three mixed systems of CHAPS with MEGA-8, -9 and -10 in pH 7.2 phosphate buffer solution.

By means of surface tension measurement (Wilhelmy method), micellization and adsorbed film formation were investigated for three combinations of mixed surfactant systems, all of which are used for solubilizing membrane proteins: a typical zwitterionic surfactant, CHAPS (a derivative of cholic acid) with n-alkyl (octyl, nonyl and decyl)-N-glucamides, MEGA-n (n=8, 9, 10). The data based on plotting of surface tension (gamma) versus logarithmic total molarity (or molality) (Ct or Mt) as a function of mole fraction of surfactant 2 (2 corresponds to MEGA-n's) enabled us to determine critical micellization concentration (CMC), minimum surface tension at CMC (gammaCMC), surface excess (Gamma(t)), mean molecular surface area (Am), the minimum Gibbs energy (Gmin(S)) of adsorbed film of both single and mixed surfactant systems and partial molecular area (PMA) in addition to parameters such as pC20 and CMC/C20 being related to synergism accompanied by blending (mixing) in regard to surface activity as well as micelle forming ability. On the basis of the regular solution theory, the relations of compositions of singly dispersed phase (X2), micellar phase (Y2) and adsorbed film (Z2) were estimated, and then the interaction parameters in micelles (omegaR) and in the adsorbed film phase (omegaA) were also calculated.

The effect of cholesterol and monosialoganglioside (GM1) on the release and aggregation of amyloid beta-peptide from liposomes prepared from brain membrane-like lipids.

In order to investigate the influence of cholesterol (Ch) and monosialoganglioside (GM1) on the release and subsequent deposition/aggregation of amyloid beta peptide (Abeta)-(1-40) and Abeta-(1-42), we have examined Abeta peptide model membrane interactions by circular dichroism, turbidity measurements, and transmission electron microscopy (TEM). Model liposomes containing Abeta peptide and a lipid mixture composition similar to that found in the cerebral cortex membranes (CCM-lipid) have been prepared. In all, four Abeta-containing liposomes were investigated: CCM-lipid; liposomes with no GM1 (GM1-free lipid); those with no cholesterol (Ch-free lipid); liposomes with neither cholesterol nor GM1 (Ch-GM1-free lipid).

An artificially designed pore-forming protein with anti-tumor effects.

Protein engineering is an emerging area that has expanded our understanding of protein folding and laid the groundwork for the creation of unprecedented structures with unique functions. We previously designed the first native-like pore-forming protein, small globular protein (SGP). We show here that this artificially engineered protein has membrane-disrupting properties and anti-tumor activity in several cancer animal models.

Nanotubules formed by highly hydrophobic amphiphilic alpha-helical peptides and natural phospholipids.

We previously reported that the 18-mer amphiphilic alpha-helical peptide, Hel 13-5, consisting of 13 hydrophobic residues and five hydrophilic amino acid residues, can induce neutral liposomes (egg yolk phosphatidylcholine) to adopt long nanotubular structures and that the interaction of specific peptides with specific phospholipid mixtures induces the formation of membrane structures resembling cellular organelles such as the Golgi apparatus. In the present study we focused our attention on the effects of peptide sequence and chain length on the nanotubule formation occurring in mixture systems of Hel 13-5 and various neutral and acidic lipid species by means of turbidity measurements, dynamic light scattering measurements, and electron microscopy. We designed and synthesized two sets of Hel 13-5 related peptides: 1) Five peptides to examine the role of hydrophobic or hydrophilic residues in amphiphilic alpha-helical structures, and 2) Six peptides to examine the role of peptide length, having even number residues from 12 to 24.

Roles of peptide-peptide charge interaction and lipid phase separation in helix-helix association in lipid bilayer.

The roles of peptide-peptide charged interaction and lipid phase separation in helix-helix association in lipid bilayers were investigated using a model peptide, P(24), as a transmembrane alpha-helical peptide, and its four analogues. Fluorescence amino acids, tryptophan (P(24)W) and pyrenylalanine (P(24)Pya), were introduced into the sequence of P(24), respectively. Association of these peptides permits the resonance excitation energy transfer between tryptophan in P(24)W and pyrenylalanine in P(24)Pya or excimer formation between P(24)Pya themselves.