Desangeloylshairidin,X-ray structure determination of a sesquiterpene lactone from Guillonea scabra

The structure and absolute configuration of desangeloylshairidin, a guaianolide isolated from Guillonea scabra, have been established by X-ray diffraction analysis. No conformational change was observed in its seven-membered ring between the crystal and deuterochloroform solution states.     

Heritable fragile sites on human chromosomes. X. New folate-sensitive fragile sites: 6p23, 9p21, 9q32, and 11q23

Four new folate-sensitive fragile sites are documented at 6p23, 9p21, 9q32, and 11q23. These have all been shown to be heritable except for the one at 9p21, which has been seen only in a single individual. As with the other autosomal fragile sites, these appear to be innocuous in heterozygotes.     

Monoclonal antibodies to neurospora adenylate cyclase

A monoclonal antibody against $\text{Neurospora}$ soluble adenylate cyclase was obtained. The antibody inhibits cyclase activities from several lower eucaryotic organisms but not activities associated to testicular cytosol or turkey erythrocyte membranes.     

Topography of the subunits of Micrococcus lysodeikticus F1-ATPase

Summary The combined use of proteolytic digestion and lactoperoxidase catalyzed labelling with [¹²⁵I] applied to membrane-bound or soluble pure F₁-ATPase from Micrococcus lysodeikticus has allowed us to establish the topography of its , , and subunits within the protein molecule and with respect to the plane of the membrane.The subunit is most externally located to the membrane bilayer looking towards the cytoplasmic face, a position consistent with its proposed catalytic role. The and subunits lie in an intermediate layer between the subunits and the membrane, in which the subunit occupies a central position within the F₁-ATPase molecule in contact with the subunit. The subunit appears to be tightly bound to the F₀ component of the ATPase complex, probably buried in the membrane bilayer. A molecular arrangement of M. lysodeikticus ATPase is proposed that, taking into account the subunit stoichiometry _{3 3 2 2} (MW 420 000), accommodates the role assigned to each subunit and most, if not all, the known properties of this bacterial energy-transducing protein.     

Lipid-bound sugars in malignant human breast tumors

Microsomal preparations from malignant human breast tumors catalyzed the transfer of mannose and glucose from GDP-[14C]-Man and UDP-[14C]-Glc into lipid-linked sugars and glycoprotein-like substances. As judged by several criteria the obtained lipid-linked monosaccharides behaved as dolichyl phosphate mannose and dolichyl phosphate glucose whereas lipid-linked oligosaccharides behaved as polyprenyl diphosphate derivatives. The optimum conditions for mannosyl- and glucosyl-transfer reactions and the effect of dolichyl phosphate, detergent and EDTA on incubation mixture were described.     

Further Assessment of Rosette Inhibition Test in Clinical Organ Transplantation

The rosette inhibition test was used in the clinical management of organ allografts to estimate the amount of immunosuppressive drugs necessary to prevent rejection. In patients surviving more than three months renal function appeared to be better than in a similar group of patients managed without the test. It is suggested that this was due to a reduction in the number of clinical or subclinical rejection episodes. On the other hand, the test indicates that in many cases the level of immunosuppression should be much higher, and if this advice is followed the patients become increasingly exposed to the risk of infection. In other words, those patients with good renal function remained well, whereas those who might otherwise have rejected their kidney and survived had in fact died of sepsis.     

The incorporation of J chain into reassembled human immunoglobulin M

Human IgM (immunoglobulin M) was reduced with 24mm-mercaptoethylamine. This atreatment resulted in complete dissociation to IgMs subunits and free J chain. Intr-subunit interchain disulphide bonds remained intact. The mixture then was encouraged to reoxidize. The schlieren pattern of the reoxidized mixture showed the presence of a considerable quantity of IgM in addition to residual IgMs. The isolated reassembled IgM did not dissociate in 5m-guanidinium hydrochloride. It apparently contained the same amount of covalently attached J chain as did native IgM. The J chain was a part of the high-molecular-weight Fc fragment obtained from the reassembled IgM.     

Localization and Properties of Enzymes Involved with Electron Transport Activity in Mycobacteria

A study of the subcellular localization of the nicotinamide adenine dinucleotide (NADH)-3-(4, 3-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT) oxido-reductase systems in Mycobacterium was presented. Evidence based on starch gel electrophoresis and different responses of the subcellular fractions to heat inactivation suggested the existence of more than one enzyme responsible for the NADH-MTT oxido-reductase activity. One type of activity was found in the membrane-mesosome fraction which contained labile and electrophoretically non-migrating enzymes. Another type of activity was also detected in the soluble fraction which on starch gel electrophoresis exhibited 4 bands of activity, two of which showed heat resistance.