SDS removal from protein by polystyrene beads

The applications of sodium dodecyl sulfate (SDS) to molecular weight determination (1,2) and for the separation of protein subunits (3) have been of immense value in biochemical studies [see Waehneldt (4) for a general review]. The tight stoichiometric binding of SDS to polypeptide chains has proven to be a nuisance if one desires to recover the activity of the isolated polypeptides. Removal of the SDS has been affected by the use of anion exchangers in the presence (5,6) and absence of urea (6). However, the residual levels of SDS or urea are often quite unsatisfactory for further protein studies.We have attempted to adapt the procedure of Holloway for the removal of Triton X-100 by Bio-Beads to the removal of SDS. We chose bovine serum albumin as a test protein since it has well-established strong binding properties for linear-chain fatty acids (7).     

Association of diamine oxidase and ornithine decarboxylase with maturing cells in rapidly proliferating epithelium.

Diamine oxidase and ornithine decarboxylase activities are shown to have a parallel distribution across rat small intestine mucosa; levels of both enzyme activities are sharply higher in mature cells in the villus tip region than in proliferating cells in the crypt areas. Histidine decarboxylase levels were not measurable in the same cell preparations and aromatic-L-amino-acid decarboxylase activity was distributed in an opposite pattern to diamine oxidase and ornithine decarboxylase. The results suggest that intestinal diamine oxidase could be involved with polyamine metabolism. The new findings for ornithine decarboxylase suggest an in vivo role for polyamines in non-proliferative cells; rat small intestinal mucosa may be an excellent model for investigating the function of polyamines in regenerating cells.     

Fine structure of sporogenesis and septum formation in Micromonospora globosa Kriss and M. fusca Jensen.

Sporogenesis in two species of Micromonospora M. globosa and M. fusca (Actinomycetes) was quite similar. As in fungi, spore formation began as a blowing-out of a hyphal tip with the subsequent centripetal invagination of the plasma membrane. Septal wall material was deposited in a typical three-layered pattern, i.e., two electron-opaque layers separated by an electron-transparent layer. A second electron-opaque wall layer was later formed within the spore and finally a third, less electron-opaque wall was produced. Spore dihiscence was facilitated by the fragmentation of the first-formed wall surrounding the spore. Sporogenesis in Micromonospora is blastic in nature producing terminal, thick-walled spores. In M. fusca, a sporulation process was observed which closely resembled sporangial formation. The process appeared similar to that described for the genus Actinoplanes. Swollen, multiseptate structures were also present. Also in M. fusca, perforate septa with flared pore margins were observed. These septa were similar in appearance to the dolipore septa of Basidiomycetes although they lack a parenthesome and pore plug. Although an extensive membrane system (mesosome) was associated with the finishing septum, its function in the process of septum formation was not determined.     

Analysis of ribosomes by polyacrylamide gel electrophoresis (author's transl)]

Ribosomal polymers, monomers and subunits from several eukaryotes and prokaryotes were isolated and analyzed by polyacrylamide gel electrophoresis. Extraction of RNA from ribosomal particles after their migration in a polyacrylamide gel, analyses by sedimentation in sucrose gradients and observations in the electron microscope were carried out in parallel. Attention was directed to the reproducibility, the precision and the limitations of the electrophoresis technique.     

Effect of cytosine arabinoside on viral-specific protein synthesis in cells infected with herpes simplex virus.

The relationship between viral DNA and protein synthesis during herpes simplex virus type 1 (HSV-1) replication in HeLa cells was examined. Treatment of infected cells with cytosine arabinoside (ara-C), which inhibited the synthesis of HSV-1 DNA beyond the level of detection, markedly affected the types and amounts of viral proteins made in the infected cell. Although early HSV-1 proteins were synthesized normally, there was a rapid decline in total viral protein synthesis beginning 3 to 4 h after infection. This is the time that viral DNA synthesis would normally have been initiated. ara-C also prevented the normal shift from early to late viral protein synthesis. Finally, it was shown that the effect of ara-C on late protein synthesis was dependent upon the time after infection that the drug was added. These results suggest that inhibition of progeny viral DNA synthesis by ara-C prevents the "turning on" of late HSV-1 protein synthesis but allows early translation to be "switched off."     

The development of experimental allergic encephalomyelitis with immunizing doses of myelin basic protein.

Rabbits immunized with low (11.25 mg) and high (57.50 mg) doses of myelin basic protein from several species develop antibasic protein antibodies, delayed type hypersensitivity, and clinical and pathological signs of experimental allergic encephalomyelitis. More than 55% of rabbits immunized with relatively high doses of basic protein develop disease. The absence of circulating antibasic protein antibodies in immunorespondent animals is associated with the appearance of clinical or histological signs of experimental allergic encephalomyelitis; however, the presence of humoral antibodies did not prevent completely the development of disease. Delayed-type hypersensitivity, specific for the basic protein, appears as early as 5 days after immunization and is maintained in nondiseased and surviving animals. Neither excess encephalitogen nor encephalitogen-induced antibody is sufficient to suppress completely the eventual development of clinical or histological manifestations of disease.     

A semiempirical theory of the optical activity of saccharides

A semiempirical theory of optical activity of saccharides is developed that (a) goes beyond previous empirical treatments, (b) yields calculated NaD rotations which correlate well with experimental data, and (c) accounts for a characteristic c.d. band observed for polysaccharides in the vacuum u.v. spectrum.     

Vacuum ultraviolet circular dichroism of fibronectin. Dominant tyrosine effects

The spectroscopic authenticity of a very intense negative band at about 183 nm reported previously from conventional circular dichroism (c.d.) studies of bovine plasma fibronectin has now been confirmed by vacuum ultraviolet c.d. measurements on two prototype spectrometers, one using a conventional light source and the other using synchrotron radiation. Closely similar spectra were obtained from both instruments, and from both solid films and solutions. The spectra show no obvious parentage in the known c.d. of the peptide backbone, but have marked similarities to the c.d. of N-acetyltyrosineamide, both in the strong band at 183 nm and in a characteristic positive band at 230 nm, It is concluded that the c.d. of fibronectin is dominated by contributions from tyrosine side-chains and that, as suggested previously, these may provide a sensitive probe for molecular organization and interactions.