IntroductionThe central goal of macromolecular synthesis is preparation of materials with tailored macroscopic properties. With increasing frequency, synthetic strategies not only address the formation of requisite covalent bonds, but also utilize the capability of molecules to self-organize. Self-William J.

Solid-state properties of the stoichiometric complexes formed by sodium poly(a,L-glutamate) and oppositely charged low molecular weight surfactants (alkyltrimethylammonium bromides) were examined by circular dichroism, infrared, and X-ray diffraction techniques. The polypeptide chains in the complexes were shown to be predominantly in the a-helical conformation at room temperature. At higher temperatures, weakening or disruption of intramolecular hydrogen bonds stabilizing the a-helical conformation was observed. The polypeptide-surfactant complexes were shown to adopt lamellar structures in the temperature range 20-150 °C. The lamellae consist of alternating layers of polyglutamate chains and bimolecular layers of surfactant, with the surfactant alkyl chains aligned perpendicular to the lamellar surfaces and interdigitated. Experimental Section Materials. Poly(a.,L-glutamic acid) sodium salt (PGNa) with weight-average degree of polymerization (DPw) (provided

The conformational and structural properties of the stoichiometric complexes formed by poly(α,l-glutamate) anions and alkyltrimethylammonium cations with chain lengths of twelve, sixteen, and eighteen carbon atoms were examined by circular dichroism, infrared, differential scanning calorimetry, and X-ray diffraction techniques. The polypeptide chains complexed with the surfactants adopt α-helical conformations. The shorter surfactant alkyl chains, consisting of twelve and sixteen carbon atoms, are disordered in the complexes, while the longer surfactant chains of eighteen carbon atoms crystallize on a hexagonal lattice. All of the complexes are organized in lamellar structures consisting of alternating layers of poly(α,l-glutamate) chains separated by bimolecular layers of the surfactants. The surfactant alkyl chains are interdigitated and perpendicular to the lamellar surfaces.

Properties of the stoichiometric complex formed by poly(L-lysine) cations and dodecyl sulfate anions in organic solvents and in the solid state were investigated via viscometry, 1 H NMR, infrared, circular dichroism, and X-ray diffraction techniques. In dilute solutions in chloroform with up to 10 vol % of trifluoroacetic acid, the complex neither forms interchain aggregates nor dissociates to yield free surfactant. In chloroform solutions containing small amounts of trifluoroacetic acid (1-2 vol %), the polypeptide chains are in an R-helical conformation, while a transition to a disordered form occurs at higher trifluoroacetic acid contents (4-6 vol %). The helix-coil transition of the poly(L-lysine) chains is accompanied by a decrease in the 1 H spin-lattice relaxation times of the polypeptide chain segments, while the relaxation times of the surfactant chains remain essentially unchanged. In chloroformtrifluoroacetic acid mixtures, the R-helical conformation of the poly(L-lysine) chains is stabilized by increasing temperature. Polypeptide chains in the solid complex can adopt either R-helical or β-sheet conformations, depending on the trifluoroacetic acid content of the chloroform solution used for film casting. The solid complex is organized into a lamellar structure consisting of alternating layers of poly(L-lysine) chains and double layers of surfactant, arranged tail to tail.

Structures of the water-insoluble complexes of poly(L-lysine) with octyl and octadedecyl sulfates, and with the mixtures of these surfactants, were examined via X-ray diffraction, infrared spectroscopy, and differential scanning calorimetry. The solid-state structures of the complexes were shown to be governed by their compositions. In the stoichiometric poly(L-lysine) complex with octadecyl sulfate, surfactant chains crystallize on a hexagonal lattice. In the poly(L-lysine)-octyl sulfate complex of nearly stoichiometric composition, the surfactants are arranged on an alkane-type two-dimensional lattice. In the complex with 20 mol % octadecyl sulfate and about 75 mol % octyl sulfate, the longer surfactant chains form hexagonal crystalline blocks, and the shorter chains are arranged on an alkanetype two-dimensional lattice. In the poly(L-lysine) complex with 10 mol % octadecyl sulfate and about 85 mol % octyl sulfate, all surfactant chains are arranged on a two-dimensional alkane-type lattice. All complexes are organized in lamellar structures consisting of layers of poly(L-lysine) chains in /J-sheet conformations, separated by layers of surfactants. Complexes with crystalline and partially crystalline surfactants adopt lamellar structures with identical long periods and with interdigitated octadecyl chains. Complexes with two-dimensional order in the surfactant arrangement also adopt lamellar structures with identical long periods and with octyl chains packed tail to tail.

Larval development of the parasitic barnacle Heterosaccus papillosus (Cirripedia: Rhizocephala: Sacculinidae) is described from larvae reared in the laboratory. Lecithotrophic nauplii of H. papillosus reached the cypris stage in 3.5 days, at 22^238C. The development included ¢ve naupliar and the single cypris stage, thus following the typical pattern in the Rhizocephala Kentrogonida. Like the nauplii of all sacculinids, those of H. papillosus had a single pigmented nauplius eye, unsegmented frontolateral horns each with two long spines and a tubercle between the furcal rami, but they lack a £otation collar and have no seta on the antennal basipod. The male larvae are larger than female ones, the mean lengths in the two sexes never overlap. The most interesting feature of this species are the morphological di¡erences between the male and female larvae. In the male nauplii III to V the anterior body margin is noticeably convex, that is not characteristic for female larvae. The male cyprid also has a more acuited anterior region, whereas that of the female is rounded.

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