The binding of ATP to the catalytic and the regulatory site of Ca2+,Mg2+-dependent ATPase of the sarcoplasmic reticulum

Two kinds of ATP binding sites were found on the ATPase molecule in deoxycholic acid-treated sarcoplasmic reticulum. One was the catalytic site (1 mol/mol active site) and its affinity was high. Upon addition of Ca²⁺, all the ATP bound to the catalytic site disappeared at 75 mM KCl, while a significant amount of ATP remained bound to the site at 0–2 mM KCl. The latter binding was found to be due to the formation of a slowly exchanging enzyme-ATP complex, which is in equilibrium with phosphoenzyme + ADP. The other binding site was the regulatory one (1 mol/mol active site) and its affinity was low, changing only insignificantly upon addition of Ca²⁺. The ATP binding to the regulatory site shifted the equilibrium between the slowly exchanging complex and EP toward EP.     

Application of the two-dimensional nmr techniques on a des(Ala,Gly)-somatostatin analog

Two-dimensional nmr techniques have been carried out for the peak assignment of the spectrum of a somatostatin analog. Two-dimensional J-resolved spectroscopy simplified the rather broad and complicated spectrum to show the center of chemical shifts of each resonance and gave information on the coupling profiles. Another technique, two-dimensional spin-echo correlated spectroscopy, revealed the connectivities between protons which are correlated by weak spin–spin couplings. The combination of the results of these two complementary techniques made it possible for us to assign almost all peaks of the spectrum of the 11-residue somatostatin analog.     

Metabolites of mating pheromone,rhodotorucine A, by a cells of Rhodosporidiumtoruloides

Rhodotorucine $\text{A}$ which induces mating tube formation of $\text{a}$ cells in $\text{Rhodosporidium}\text{toruloides}$ is metabolized rapidly by $\text{a}$ cells. By use of labeled rhodotorucine $\text{A}$, the degradation was found to be proteolytic. Two peptide fragments Tyr-Pro-Glu-Ile-Ser-Trp-Thr-Arg and Asn-Gly-Cys(S-farnesyl) were identified as the metabolites. Proteolysis of the pheromone mainly occurred on the cell surface. Culture filtrate of $\text{a}$ cells at log phase did not metabolize rhodotorucine $\text{A}$.     

Modification of human hemoglobin with polyethylene glycol: A new candidate for blood substitute

Human hemoglobin was modified with polyethylene glycols. The conjugates exhibited P₅₀ values of 10–15 mmHg, those are enough to deliver oxygen from the lungs to tissues. The most remarkable characteristic is their long half disappearance time from the circulation. The longest half disappearance time of these derivatives is about 180 minutes in contrast to 45 minutes of free hemoglobin. The half disappearance time shows a good corelation not to molecular weight but to the effective molecular size, which is determined by the elution time of HPLC on a gel permeation column.     

Fibrin membrane endowed with biological function VI. Immobilization of multienzymes of urea cycle

Four enzymes in urea cycle and inorganic pyrophosphatase were immobilized simultaneously into a matrix of fibrin fiber formed from fibrinogen by the concerted action of thrombin and blood coagulation Factor XIII. The immobilized multienzyme system not only had an ability to carry out urea cycle continuously at least over several hours, but also had a greatly improved efficiency over the corresponding soluble system.     

The insecticidal activity of some norditerpene dilactones

The effects on housefly (Musca domestica) of six norditerpene lactones (nagilactones B, D, E, podolide, hallactone B and 14-epi-ponalactone A) in a defined diet were tested. Nagilactone D was the most active, with an LD₅₀ of 0.7 ppm. Nagilactones C and D were also toxic to light-brown apple moth (Epiphyas postvittana) and codling moth (Laspeyresia pomonella).The relationship between lactone structure and toxicity to housefly is discussed.

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Zusammenfassung Viele aus Podocarpus-Arten isolierte Norditerpenlactone sind für Stubenfliegen toxisch. Es wird über die Resultate der Fütterung von sechs Lactonen an die Stubenfliege in einem definierten Nährboden berichtet und die LD₅₀ von zwölf Verbindungen werden verglichen. Der aktivste Stoff ist Nagilacton mit einer LD₅₀ von 0,7 ppm. Nagilacton C und D sind auch toxisch für Epiphyas postvittana und für den Apfelwickler. Die wirksamsten Verbindungen haben eine kurze nichtpolare Seitenkette und eine elektronenreiche, funktionelle Gruppe bei C-8, ferner sind sie Epoxyalkohole in Ring-A. Diese in der Natur vorkommenden Lactone spielen wahrscheinlich eine Schutzrolle in der Pflanze.

     

Novel mutations in ADAMTS13 CUB domains cause abnormal pre-mRNA splicing and defective secretion of ADAMTS13

Hereditary thrombotic thrombocytopenic purpura (TTP) is an autosomal recessive thrombosis disorder, caused by loss-of-function mutations in ADAMTS13. Mutations in the CUB domains of ADAMTS13 are rare, and the exact mechanisms through which these mutations result in the development of TTP have not yet been fully elucidated. In this study, we identified two novel mutations in the CUB domains in a TTP family with an acceptor splice-site mutation (c.3569−1, G>A, intron 25) and a point missense mutation (c.3923, G>A, exon 28), resulting in a glycine to aspartic acid substitution (p.G1308D). In vitro splicing analysis revealed that the intronic mutation resulted in abnormal pre-mRNA splicing, and an in vitro expression assay revealed that the missense mutation significantly impaired ADAMTS13 secretion. Although both the patient and her brother displayed significantly reduced ADAMTS13 activity and increased levels of ultra-large VWF (ULVWF) multimers in plasma, only the female developed acute episodes of TTP. Our findings indicate the importance of the CUB domains for the protein stability and extracellular secretion of ADAMTS13.