Unsaturated Hydrocarbon Chains Research Articles

Reaction of ethyl diazoacetate with allylamines catalyzed by copper and rhodium complexes

The reaction of ethyl diazoacetate with allylamine by the action of low-valence copper and rhodium complexes is accompanied by structural isomerization of the unsaturated hydrocarbon chain and the insertion of ethoxycarbonylcarbene into the C-H allylic bonds with the formation of ethyl esters of unsaturated amino acids.

Monolayer Studies of Insulin–Lipid Interactions

□ The interactions between insulin and various lipids were studied by monolayer penetration experiments at constant surface area. The increase in surface pressure, ΔΠ, of a lipid film depended upon the particular lipid used and the concentration of insulin in the subphase. For all lipids studied, ΔΠ was dependent on the initial surface pressure of the lipid film. Evidence of the interaction between insulin and the lipids was found in the ability of insulin to penetrate lipid films with initial pressures >16 dynes/cm, the maximum surface pressure obtained by insulin alone. For phospholipids, both the nonpolar and polar regions influenced the degree of interaction with insulin. Saturated chain lecithins exhibited less penetration than phospholipids with unsaturated hydrocarbon chains. The net charge of the lipid was not found to be an important determinant of penetration; however, the structure of the polar group can have a dramatic effect. Insulin penetration of mixed lipid films cannot be predicted by the penetration characteristics of the pure components. The possible role of these interactions in determining the geography of the insulin molecule within the liposome and its resultant effects on the stability is discussed.

Lipid-protein interaction in the photolysis of octopus rhodopsin

Microvillar membranes of octopus photoreceptor cells were treated with phospholipase A 2, phospholipase C, hexane, or their combinations. By these means, various membrane preparations containing qualitatively and quantitatively different lipids were obtained. The lipid composition and phospholipid content of the membrane preparations obtained by the above methods were determined. Photochemical processes in the digitonin extract of the native and treated membranes have been studied by flash photometry. The results suggest that several different variations in the lipids can affect the rates of the photochemical transformations; these are: the content of phospholipid, the amount of unsaturated hydrocarbon chains and free fatty acids.

Host Selection by Hylemya antiqua: 1 Identification of Oviposition Stimulants Based on Proposed Active Thioalkane Moieties 2

Based on previous studies which identified onion-produced oviposition stimulants for the onion maggot, Hylemya antiqua (Meigen), it was hypothesized that a common thiopropyl functional group was responsible for olfactory receptor stimulation. Experimental examination of this hypothesis revealed specifically the requirement of a single sulfur atom with 2 unshared electron pairs, bonded 10 a saturated hydrocarbon chain 3–5 carbons long. Associated groups compatable with the active structures ranged from a single hydrogen as in propanethiol, to saturated and unsaturated hydrocarbon chains 1–5 carbons long. Molecular moieties nullifying the oviposition inducing properties of the active structures were observed in propyl thiocyanate, dipropyl sulfoxide and propionaldehyde dipropylthioacetal. New oviposition stimulants identified on the basis of the initial and revised hypothesis are: dipropyl sulfide, cis - and trans -propenyl propyl sulfide, methyl propyl sulfide, dibutyl disulfide, methyl butyl disulfide, dipentyl disulfide, dipropyl trisulfide, 2-butyl propyl sulfide and butanethiol.

Raman spectra of some saturated, unsaturated and deuterated C 18 fatty acids in the HCH-deformation and CH-stretching regions

We have analyzed the Raman spectra of stearic acid and two deuterated derivatives thereof, 2,2-dideutero stearic acid and 18,18,18-trideutero stearic acid, as well as of four unsaturated, C 18 acids, ( cis, cis,-9; cis, cis-9,12, cis, cis, cis-9,12,15; and trans, trans-9,12) in their solid and liquid states. The different spectra of stearic acid and the two deuterated derivatives exhibit distinctive HCH-deformation and CH-stretching features for CH 2 residues adjacent to CO 2H or CH 3 residues. Unsaturated hydrocarbon chains reveal additional features attributed to CH 2 residues adjacent to one or two HCCH groups. The spectra of the various fatty acids in their solid or liquid states show that both the HCH-deformation and CH-stretching regions are very sensitive to chain architecture, the CH-stretching region most dramatically so. Evaluation of the spectral features in the two regions indicates that the detailed structure of the CH-stretching region depends strongly upon interaction, enhanced by Fermiresonance, between CH-stretching fundamentals and HCH-deformation overtones. The data further suggest that the differences between HCH-deformation, in the solid and liquid states, and the resulting altered interactions between CH-stretching fundamentals and HCH-deformation overtones, produce the large modifications of the CH-stretching region that accompany solid-liquid transitions. The results thus provide a basis for the changes in the CH-stretching region, that accompany order-disorder transitions in model and biological membranes.

Interaction of different forms of haemoglobin with artificial lipid membranes

The action of different forms of haemoglobin (oxy-, carboxy- and methaemoglobin) and myoglobin on the leakage of Rb + out of liposomes has been investigated. The results presented will demonstrate that only methaemoglobin is particularly effective in interacting with phospholipid vesicles by changing their permeability and catalyzing a peroxidation of their unsaturated hydrocarbon chains.

Phospholipids of Clostridium butyricum. V. Effects of growth temperature on fatty acid, alk-1-enyl ether group, and phospholipid composition

Many anaerobic bacteria have a high proportion of 1-alk-1'-enyl ethers (plasmalogens) among their phospholipids. We have examined the effects of growth temperature on the phospholipid, fatty acid, and alk-1-enyl group compositions of Clostridium butyricum. When the growth temperature was decreased from 37 degrees C to 25 degrees C, the proportion of glycerol phosphoglycerides (the sum of phosphatidylglycerol and the corresponding plasmalogen) increased at the expense of the ethanolamine and N-methylethanolamine phosphoglycerides. Analysis of the proportion of these lipids present in the diacyl and 1-alk-1'-enyl-2-acyl forms has shown a substantial increase in the plasmalogen form of the glycerol phosphoglycerides and a decrease in the plasmalogen forms of the ethanolamine and N-methylethanolamine phosphoglycerides. An analysis of the fatty acids and alk-1-enyl groups isolated from the total phospholipids of cells grown at 25 degrees C, 30 degrees C, and 37 degrees C has shown a general increase in the proportions of unsaturated and cyclopropane hydrocarbon chains at lower growth temperatures. When the temperature was lowered from 37 degrees C to 25 degrees C, the fatty acids had progressively more unsaturated and cyclopropane chains and fewer saturated chains. The alk-1-enyl groups, in particular those from the ethanolamine and N-methylethanolamine plasmalogens, were more saturated at 30 degrees C than at 37 degrees C. When the growth temperature was lowered to 25 degrees C, there was little further change in the degree of unsaturation of the alk-1-enyl groups.

The effect of surface charge on the water permeability of phospholipid bilayers

1. 1. Bilayers have been made from phosphatidylcholine and phosphatidylserine. 2. 2. By means of an osmotic technique, the water permeability coefficient P os has been measured for different values of pH. 3. 3. The value of P os for phosphatidylcholine bilayers (1.8·10 −5 m·s −1) does not vary with pH within the range of 3.0–7.4. 4. 4. The value of P os for phosphatidylserine varies from 0.86·10 −5 m·s −1 at pH 3.0 to 1.25·10 −5 m·s −1 at pH 9.0. 5. 5. The increase in P os with pH for phosphatidylserine bilayers has been interpreted in terms of an increase of configurational freedom of hydrocarbon chains resulting from an increase in surface area per molecule. 6. 6. The large difference between the phosphatidylcholine value for the water permeability coefficient and the phosphatidylserine values is interpreted in terms of differences in hydrocarbon chain unsaturation.

The effect of ultrasonic irradiation on the chemical structure of egg lecithin

Prolonged exposure of egg lecithin dispersions to ultrasound of low intensity and short exposure to ultrasound of high intensity lead to appreciable chemical degradation even in the presence of N 2 although oxidation of the unsaturated hydrocarbon chains is then prevented. The main degradation products are lysolecithin, fatty acids, glycerylphosphorylcholine, phosphorylcholine and choline. The amount of lysolecithin depends on the intensity of ultrasonic cavitation. Some of the physical properties of egg lecithin sonicated under conditions which eliminate the possibility of chemical degradation are studied and compared with results of other workers.

The effect of temperature and hydrocarbon chain structures on the titration properties of lecithin and some related phospholipids

The effect of temperature and hydrocarbon structure on the ionic properties of aqueous dispersions of lecithin and some related compounds was studied by titrations and other pH measurements. The reactions of lecithin with NaOH at elevated pH levels increased with temperature. This effect was greater with short-chain or unsaturated hydrocarbon groups and appeared to be related to the temperature for the transition to the liquid crystalline form. Systems of dimyristoyl or dipalmitoyl lecithin when brought to pH 9 and heated from 20°C showed a sharp drop in pH at the characteristic transition temperature for the formation of the smectic form. Dipalmitoyl phosphatidyl ethanolamine dispersions showed very little reaction with NaOH and raising the system to 45°C produced little increase. The same lipid obtained from soybean or beef showed greatly increased reaction with base at temperatures above 24°C. This difference is attributed to their unsaturated hydrocarbon chains.

X-Ray Diffraction Studies of Organic Cation-Stabilized Bentoniteby

AbstractStudies of quaternary ammonium chlorides containing long unsaturated hydrocarbon chains have shown their effectiveness in stabilizing soils primarily by waterproofing the clay fraction. The nature of the interaction between organic salts and Wyoming bentonite was studied by means of X-ray diffraction.Treatment of bentonite with a dialkyl dimethyl ammonium salt in an amount less than the exchange capacity results in the appearance of water-stable spacings of 10, 13 and 19 Å, but only if the sample has been dry cured. Moist curing a bentonite paste results in a marked expansion of the lattice despite treatment. The necessity of dry curing may relate to orientation of organic cations around bentonite aggregates; grinding prior to rewetting destroys the waterproofing action, and the clay lattice again expands.Additions of the quaternary ammonium cations close to or in excess of the exchange capacity of the bentonite waterproofs regardless of dry curing or grinding, or both. Clays treated in this manner show spacings of the pure crystalline chemicals and other spacings which relate to interlayer penetration by water. There is no direct evidence for interlayer penetration by the organic cation, perhaps because of the unwieldy tetra-hedral arrangement of the organic molecule. The degree to which organic cations are held depends on the nature of the surface as the cations are readily leached from quartz powder but are held more strongly on kaolinite and bentonite.