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A fluorescent base wye (Yt base) was isolated from Torulopsis utilis tRNAPhe. The structure was established as 4,9-dihydro-4,6-dimethyl-9-oxo-1H-imidazo[1,2-alpha]purine based on ultraviolet (uv), nuclear magnetic resonance (NMR), and mass spectra, and by direct comparison with synthetic material. The nucleoside, wyosine (Yt), was isolated from purified tRNAPhe by enzymatic degradations followed by column and thin-layer chromatographies. The structure of wyosine is proposed as 3-ribofuranosyl-4,9-dihydro-4,6-dimethyl-9-oxo-1H-imidazol[1,2-alpha]purine (the ribosyl group is attached to the N-9 position of guanine nucleus) on the basis of comparison with model compounds.

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The kinetic studies of chemical modifications of the lysine and arginine residues of the nucleosome core particle from chicken erythrocytes with large molar excesses of 2,4,6-trinitrobenzenesulfonic acid and 2,3-butanedione, respectively, were performed over 20 mM-2.0 M NaCl. Each modification reaction was divided into the two, a rapid and an extremely slow, pseudo-first-order processes, and the numbers of the exposed and buried residues of the respective amino acids were determined. At very low ionic strength (20 mM boric buffer) all residues were inaccessible to the reagents. Between 0.3 and 0.6 M NaCl the basic amino acid residues in a nucleosome core particle were classified into the following three groups: (1) 42 arginine and 78 lysine residues in the N-terminal and C-terminal regions of the histones that are exposed to solvent, (2) a small number of arginine residues (approximately less than 14 Arg) that are strongly bound to the DNA phosphates, and (3) 48 arginine and 38 lysine residues buried in the globular region of the histone octamer. The results suggest that a small number of arginine residues play an essential role in the folding of DNA into a nucleosome core particle.

SynopsisThe conformational transition of poly(L-arginine) by binding with various mono-, di-, and polyvalent anions, especially with SO:-, was studied by CD measurements. The intramolecular random coil-to-a-helix conformational transition and the subsequent transition to the 0-turn-like structure was caused by binding with SO:-. The binding data obtained from equilibrium dialysis experiments showed that the a-helical conformation of poly(i-arginine)is stabilized a t a 1:3 stoichiometric ratio of bound SO: -to arginine residue; a t higher free SO:-concentrations, the a-helix converts to the 0-turn-like structure accompanied by a decrease in the amount of bound SO:-. The same conformational transition of poly(L-arginine) also occurred in the solutions of other divalent anions (SO:-, COZ-, and HPO:-) and polyvalent anions (P20$-, PsO:;). Among the monovalent anions examined, Cloy and dodecyl sulfate were effective in inducing a-helical conformation, while the other monovalent anions (OH-, C1-, F-, H2POI, HCO,, and C10,) failed to induce poly(L-arginine) to assume the a-helical conformation. Thus, we noticed that, except for dodecyl sulfate, the tetrahedral structure is common to the a-helix-forming anions. A well-defined model of the a-helical poly(Larginine)/anion complex was proposed, in which both the binding stoichiometry of anions to the arginine residue and the tetrahedral structure of anions were taken into consideration. Based on these results, it was concluded that the tetrahedral-type anions stabilize the a-helical conformation of poly(L-arginine) by crosslinking between two guanidinium groups of nearby side chains on the same a-helix through the ringed structures stabilized by hydrogen bonds as well as by electrostatic interaction. Throughout the study it was noticed that the structural behavior of poly(L-arginine) toward anions is distinct from that of poly(L-lysine).

In order to clarify the roles of lipids in the water-holding property of stratum corneum, the forearm skin of healthy male volunteers was treated with acetone/ether (1/1) or sodium dodecyl sulfate (5%) for 1-30 min.A prolonged treatment period of 5-30 min produced a chapped and scaly appearance of the stratum corneum without any inflammatory reactions.Under these conditions, there was a marked decrease in the water-holding capacity of the stratum corneum accompanied by a selective loss of stratum corneum lipids such as cholesterol, cholesterol esters, and sphingolipids. Two daily applications of the isolated stratum corneum lipids to experimentally induced dry skins caused a significant increase of conductance r accompanied by a marked improvement in the level of scaling.Meanwhile, the isolated sebaceous lipids exhibited no significant recovery in both the conductance value and the scaling.Out of chromatographically separated fractions of the stratum corneum lipids, topical applications of ceramide fraction induced the highest increase in the conductance value.Topical applications of synthesized pseudo-ceramides also showed a significant recovery of the water-retaining properties accompanied by an improvement in the scaling only when the polar group has an amide bond in the major linkage.Analysis of the alkyl chain structures has revealed that a structural requirement for the recovery of the water retaining capacity is the presence of saturated-straight alkyl chains, not unsaturated or branched alkyl chains. These structural characteristics required for water-retaining function also paralleled their capacity to form multiconcentric lamellae vesicles in vitro which is also capable of acquiring bound water as shown by """"DSe-t'Fiermograms. The present study suggests that ceramides with relatively shorter alkyl chain length serve as a water modulator in the multi-lipid bilayers through the stratum corneum.

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