Avidin, a positively charged egg‐white protein, aggregates extensively when mixed at ambient temperatures with anionic detergents, such as sodium dodecyl sulfate (SDS). The resultant aggregates fail to penetrate the stacking gel during polyacrylamide gel electrophoresis (PAGE). To prevent the formation of such aggregates, avidin was acetylated and the p I was thus reduced. Acetylated avidin was found to behave in a manner similar to that of streptavidin; under nondenaturing conditions ( i.e. , incubation of samples at room temperature), both proteins normally migrated mainly as tetramers with a tendency to form oligomers of the tetramer. When samples were boiled, both proteins migrated mainly as the monomer. The comparative stability properties of avidin and streptavidin were also examined using SDS‐PAGE by heating samples and determining the extent of dissociation of tetramers to monomers as a function of temperature. A distinctive transition temperature could be defined for individual samples. Using this assay, it was determined that, in the absence of biotin, the quaternary structure of streptavidin is more stable than that of avidin. Biotin appears to stabilize structures of both avidin and streptavidin to a similar degree. Acetylation of avidin thus provides a simple means to analyze the quaternary structure of the molecule using SDS‐PAGE.

Soybean agglutinin, a lectin specific for N-acetyl-d-galactosamine and d-galactose, was previously shown to agglutinate wheat leaf protoplasts (Larkin 1978 Plant Physiol 61: 626-629). We investigated the receptors for soybean agglutinin on the plasma membrane of these protoplasts. After treatment of the protoplasts with galactose oxidase, they were no longer agglutinated by the lectin, whereas upon reduction of the galactose oxidase-treated protoplasts with sodium borohydride the susceptibility to agglutination was restored. Analysis of the glycolipids of protoplasts surface labeled by the galactose oxidase-borotritide method, revealed that the radioactivity was mainly present in monogalactosyldiglyceride and digalactosyldiglyceride. The same galactolipids were identified as the only receptors for soybean agglutinin by direct binding of the (125)I-labeled lectin to a thin layer chromatogram of the glycolipids of wheat leaf protoplasts.

Polymeric pseudocrown ethers, incorporating oxyethylene and oxypropylene units, extract FeCl4− from mixed hydrochloric and phosphoric acids. The complexation depends on hydrochloric acid concentration and becomes efficient when the HCl concentration exceeds 4 M. The regeneration of the polymers is accomplished with water. Column tests have been shown to separate iron very efficiently from phosphoric acid, which is recovered quantitatively. In comparison, Amberlyst A-21, a weak-base anion exchanger, shows affinity for phosphoric acid, making the separation between iron and phosphorus difficult.

Mercury and silver were extracted from aqueous solutions by insoluble copolymers of styrene-divinylbenzene incorporating isothiourea groups. The metals were released from the polymers by combustion with a perchloric acid-nitric acid mixture (3:7) and determined titrimetrically. The method was used to measure distribution curves for the two metals from aqueous solutions, and to determine silver in photographic laboratory spent solutions.

FEBS LettersVolume 82, Issue 2 p. 191-196 Full-length articleFree Access Transition metal requirements of soybean agglutinin Charles L. Jaffe, Charles L. Jaffe Department of Biophysics, The Weizmann Institute of Science, Rehovot, IsraelSearch for more papers by this authorSarah Ehrlich-Rogozinski, Sarah Ehrlich-Rogozinski Department of Biophysics, The Weizmann Institute of Science, Rehovot, IsraelSearch for more papers by this authorHalina Lis, Halina Lis Department of Biophysics, The Weizmann Institute of Science, Rehovot, IsraelSearch for more papers by this authorNathan Sharon, Nathan Sharon Department of Biophysics, The Weizmann Institute of Science, Rehovot, IsraelSearch for more papers by this author Charles L. Jaffe, Charles L. Jaffe Department of Biophysics, The Weizmann Institute of Science, Rehovot, IsraelSearch for more papers by this authorSarah Ehrlich-Rogozinski, Sarah Ehrlich-Rogozinski Department of Biophysics, The Weizmann Institute of Science, Rehovot, IsraelSearch for more papers by this authorHalina Lis, Halina Lis Department of Biophysics, The Weizmann Institute of Science, Rehovot, IsraelSearch for more papers by this authorNathan Sharon, Nathan Sharon Department of Biophysics, The Weizmann Institute of Science, Rehovot, IsraelSearch for more papers by this author First published: October 15, 1977 https://doi.org/10.1016/0014-5793(77)80582-6Citations: 28AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume82, Issue2October 15, 1977Pages 191-196 ReferencesRelatedInformation