We previously reported a combinatorial strategy for designing alpha-helical proteins by assigning only the binary patterning of polar or nonpolar residues [Kamtekar, S., Schiffer, J. M., Xiong, H. Y., Babik, J. M., and Hecht, M. H. (1993) Science 262, 1680-1685]. Here we describe the finding that approximately half of the proteins in the original collection display some level of cooperativity i...

The authors develop an ultrasensitive method for the measurement of the charge carried by a colloidal particle in a nonpolar suspension. The technique uses the phenomenon of the resonance of a particle held in an optical tweezer trap and driven by a sinusoidal electric field. The trapped particle forms a strongly damped harmonic oscillator whose fluctuations are a function of gamma, the ratio o...

Bovine adrenal cortical tissue contains a lipoidal derivative of pregnenolone (3beta-hydroxy-pregn-5-en-20-one) from which the free steroid can be liberated by treatment with alkali. Evidence for the presence of such an entity comes from examination of a nonpolar extract of tissue from which pregnenolone and its sulfate had been removed by chromatography. Treatment of the nonpolar fraction with...

Drosophila bicoid mRNA is synthesized in the nurse cells and transported to the oocyte where microtubules and Exuperantia protein mediate localization to the anterior pole. Fluorescent bicoid mRNA injected into the oocyte displays nonpolar microtubule-dependent transport to the closest cortical surface, and the oocyte microtubule cytoskeleton lacks clear axial asymmetry. Nonetheless, bicoid mRN...

A method has been described for measurement of the oxidation-reduction potentials of redox couples in nonaqueous solutions. This method has been applied to a study of the effect of a nonpolar environment on the redox potential of a heme complex. A positive potential difference of some 300 mV is observed for the measured redox potentials by comparison with reported values for the corresponding h...

In our ongoing investigation into Artemisia annua for the treatment of malaria, we decided to study the possibility that synergism might enhance the efficacy of artemisinin. Our main objective was to test tea infusions and nonpolar extracts prepared from different A. annua varieties against Plasmodium falciparum in vitro in order to determine if synergism will increase the effectiveness of arte...

Experimental measurements and computational results have shown that polypeptide chains, made up of 15-25 glycine residues, collapse to compact structures in water at room temperature. This contrasts with the classic idea that the burial of nonpolar side chains, i.e., the hydrophobic effect, is the driving force of collapse and folding of polypeptides and proteins. It is thus necessary to find a...

The new lamellar phases [Zn(2,2'-bpy)(2)(H(2)O)(2)](ZrF(6))·3H(2)O (I) and [Ni(2,2'-bpy)(3)](MoO(2)F(4))·5H(2)O (II) (bpy = bipyridine), which are built from a chiral cation and respectively an inherently nonpolar and a polar anion, provide two contrasting structures with respect to chirality and polarity in the solid state. Each nonpolar layer of I contains enantiomers of both handednesses; co...

The potato (Solanum tuberosum L.) ranks third in worldwide consumption among food crops. Whereas disposal of potato peels poses significant challenges for the food industry, secondary metabolites in these tissues are also bioactive and essential to crop development. The diverse primary and secondary metabolites reported in whole tubers and wound-healing tissues prompted a comprehensive profilin...