Improvement of pulmonary surfactant activity by introducing D-amino acids into highly hydrophobic amphiphilic α-peptide Hel 13-5.

The high costs of artificial pulmonary surfactants, ranging in hundreds per kilogram of body weight, used for treating the respiratory distress syndrome (RDS) premature babies have limited their applications. We have extensively studied soy lecithins and higher alcohols as lipid alternatives to expensive phospholipids such as DPPC and PG. As a substitute for the proteins, we have synthesized the peptide Hel 13-5D3 by introducing D-amino acids into a highly lipid-soluble, basic amphiphilic peptide, Hel 13-5, composed of 18 amino acid residues.

Surface pressure induced structural transitions of an amphiphilic peptide in pulmonary surfactant systems by an in situ PM-IRRAS study.

Pulmonary surfactant model peptide, Hel 13-5, in binary and ternary lipid mixtures has been characterized employing the polarization-modulation infrared reflection-absorption spectroscopy (PM-IRRAS) in situ at the air-water interface for a monolayer state and the polarized ATR-FTIR for a bilayer film. In the bilayer form, Hel 13-5 predominantly adopts an α-helical secondary structure in the lipid mixtures. It had been made clear from CD measurements that the Hel 13-5 structure is mainly in the α-helical form in aqueous solutions.

Fluorocarbon-hybrid pulmonary surfactants for replacement therapy--a Langmuir monolayer study.

Effective additives to pulmonary surfactant (PS) preparations for therapy of respiratory distress syndrome (RDS) are being intensively sought. We report here the investigation of the effects of partially fluorinated amphiphiles (PFA) on the surface behavior of a model PS formulation. When small amounts of a partially fluorinated alcohol C(8)F(17)C(m)H(2m)OH (F8HmOH, m = 5 and 11) are added to the PS model preparation (a dipalmitoylphosphatidylcholine (DPPC)/Hel 13-5 peptide mixture) considered here, the effectiveness of the latter in in vitro pulmonary functions is enhanced.

Specific interaction restrains structural transitions of an amphiphilic peptide in pulmonary surfactant model systems: an in situ PM-IRRAS investigation.

In situ polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS) at the air-water interface has been used to determine secondary structure of the pulmonary surfactant model peptide, Hel 13-5, in the absence and the presence of phospholipid monolayers. Herein, fully saturated phospholipids of DPPC and DPPG are utilized to understand the effect of specific interaction between anionic DPPG and cationic Hel 13-5 on the peptide secondary structure. The spectrum frequency in the amide region (1500-1700cm(-1)) obtained from PM-IRRAS has been confirmed by comparing with that from ATR-FTIR for the corresponding bulk films.

Pulmonary surfactant model systems catch the specific interaction of an amphiphilic peptide with anionic phospholipid.

Interfacial behavior was studied in pulmonary surfactant model systems containing an amphiphilic alpha-helical peptide (Hel 13-5), which consists of 13 hydrophobic and five hydrophilic amino acid residues. Fully saturated phospholipids of dipalmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidylglycerol (DPPG) were utilized to understand specific interactions between anionic DPPG and cationic Hel 13-5 for pulmonary functions. Surface pressure (pi)-molecular area (A) and surface potential (DeltaV)-A isotherms of DPPG/Hel 13-5 and DPPC/DPPG (4:1, mol/mol)/Hel 13-5 preparations were measured to obtain basic information on the phase behavior under compression and expansion processes.

Hysteresis behavior of amphiphilic model peptide in lung lipid monolayers at the air-water interface by an IRRAS measurement.

Pulmonary functions such as rapid adsorption, respreading, and hysteresis behavior of pulmonary surfactants are very important for respiratory movement. The interfacial behavior of pulmonary preparations containing an amphiphilic peptide (Hel 13-5) has recently investigated. An orientation of hydrophobic chains in a dipalmitoylphosphatidylcholine (DPPC) with or without palmitic acid (PA) is associated with a collapse of alveoli during respiration process.

Development of low cost pulmonary surfactants composed of a mixture of lipids or lipids-peptides using higher aliphatic alcohol or soy lecithin.

The artificial pulmonary surfactant composition in the present study is characterized by a lipid mixture system composed of higher aliphatic alcohol, egg yolk phosphatidylcholine (egg PC), soy lecithin and higher aliphatic acid as the major components or a peptide-lipid mixture system composed of a combination of the lipid mixture system to which a peptide is added. Three peptides with amphiphilic surface-staying, membrane spanning, and both properties were designed and synthesized. The evaluation of pulmonary surfactant assay was performed by a hysteresis curve drawn upon the measurement for the surface tension-area curve with the Wilhelmy surface tensometer in vitro and the recovery of lung compliance for the pulmonary surfactant-deficient rat models in vivo.

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.

Comment on "Determination of the critical micelle concentration of dodecylguanidine monoacetate (dodine)".

In a work published in this journal by J.P.S.

Anti-tumor activity of de novo designed small globular protein (SGP) in vivo.

Background: The design and synthesis of a small globular protein (SGP) based on the colicin family of bacteriocins has previously been reported. It has subsequently been shown that this artificial protein possessed cell membrane-disrupting properties. Here, the anti-tumor effects of SGP in subcutaneous nude mice tumor models of human glioma were examined.

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.

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.