CLEAVAGE OF SEDOHEPTULOSE 1,7-DIPHOSPHATE BY A PURIFIED RAT LIVER DIPHOSPHATASE.

SUMMARY treatment. A simple procedure is described for the purification, from rat None of a variety of other monophosphate and diphosphate liver, of a diphosphatase activity which cleaves both fructose esters tested as substrates was cleaved by the purified enzyme diphosphate and sedoheptulose diphosphate to fructose 6-phos- at significant rates. These results suggest an absolute require- phate and sedoheptulose 7-phosphate, respectively. ment for the presence of two phosphate groups and also for the Evidence that a single enzyme is responsible for both reactions configuration found in FDP and SDP. n-Bibulose 1,5-diphos- is derived from the results of the purification steps, from kinetic phate differs in the configuration at C-3 and is not attacked. measurements, and from other properties. The enzyme has no With respect to the physiological role of the diphosphatase, activity with a variety of monophosphate esters and other di- although it has been generally recognized that fructose diphos- phosphate esters. phatase may represent a key enzyme in the synthesis of glycogen Both activities are present in the liver of all mammalian species from 3 carbon fragments, no direct evidence for a role of sedo- studied. heptulose diphosphatase has yet been obtained. REFERENCES Three possibilities may be considered with respect to the physiological significance of the latter activity. (a) It may be 1. GOMORI, G., J

Extracellular release of the ‘differentiation enhancing factor’, a HMG1 protein type, is an early step in murine erythroleukemia cell differentiation

AbstractDifferentiation enhancing factor (DEF) is a 29 kDa protein expressed in murine erythroleukemia (MEL) cells and active in promoting a significant increase in the rate of hexamethylenebisacetamide induced differentiation of these cells. The factor was recently shown to possess an amino acid sequence identical to that reported for one of the HMG1 proteins, designated as ‘amphoterin’ on the basis of its highly dipolar sequence. In the present study, we have expressed DEF cDNA in an E. coli strain and found that the recombinant protein has functional properties identical to those observed with native DEF. Furthermore, we demonstrate that, following MEL cell stimulation with the chemical inducer, DEF is secreted in large amounts in the extracellular medium. In fact, the N-terminal sequence and the partial amino acid sequence of tryptic peptides from the secreted protein correspond to those of DEF isolated from the soluble fraction of resting MEL cells. These results are indicative for an extracellular localization as the site of action of DEF and suggest a novel function for proteins belonging to the HMG1 family. Finally, the early decay of DEF mRNA, in chemical induced MEL cells, support the hypothesis that the involvement of the enhancing factor occurs and is completed in the early phases of cell differentiation

Reprint of: Proteomics in cardiovascular diseases::Unveiling sex and gender differences in the era of precision medicine

Cardiovascular diseases (CVDs) represent the most important cause of mortality in women and in men. Contrary to the long-standing notion that the effects of the major risk factors on CVD outcomes are the same in both sexes, recent evidence recognizes new, potentially independent, sex/gender-related risk factors for CVDs, and sex/gender-differences in the clinical presentation of CVDs have been demonstrated. Furthermore, some therapeutic options may not be equally effective and safe in men and women. In this context, proteomics offers an extremely useful and versatile analytical platform for biomedical researches that expand from the screening of early diagnostic and prognostic biomarkers to the investigation of the molecular mechanisms underlying CDVs. In this review, we summarized the current applications of proteomics in the cardiovascular field, with emphasis on sex and gender-related differences in CVDs

A Direct Interconversion: d-Fructose 6-Phosphate Sedoheptulose 7-Phosphate and d-Xylulose 5-Phosphate Catalyzed by the Enzymes Transketolase and Transaldolase

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Polyelectrolyte-coated mesoporous bioactive glasses via layer-by-layer deposition for sustained co-delivery of therapeutic ions and drugs

In the field of bone regeneration, considerable attention has been addressed towards the use of mesoporous bioactive glasses (MBGs), as multifunctional therapeutic platforms for advanced medical devices. In fact, their extremely high exposed surface area and pore volume allow to load and the release of several drugs, while their framework can be enriched with specific therapeutic ions allowing to boost the tissue regeneration. However, due to the open and easily accessible mesopore structure of MBG, the release of the incorporated therapeutic molecules shows an initial burst effect leading to unsuitable release kinetics. Hence, a still open challenge in the design of drug delivery systems based on MBGs is the control of their release behavior. In this work, Layer-by-layer (LbL) deposition of polyelectrolyte multi-layers was exploited as a powerful and versatile technique for coating the surface of Cu-substituted MBG nanoparticles with innovative multifunctional drug delivery systems for co-releasing of therapeutic copper ions (exerting pro-angiogenic and anti-bacterial effects) and an anti-inflammatory drug (ibuprofen). Two different routes were investigated: in the first strategy, chitosan and alginate were assembled by forming the multi-layered surface, and, successively, ibuprofen was loaded by incipient wetness impregnation, while in the second approach, alginate was replaced by ibuprofen, introduced as polyelectrolyte layer. Zeta-potential, TGA and FT-IR spectroscopy were measured after the addition of each polyelectrolyte layer, confirming the occurrence of the stepwise deposition. In addition, the in vitro bioactivity and the ability to modulate the release of the cargo were evaluated. The polyelectrolyte coated-MBGs were proved to retain the peculiar ability to induce hydroxyapatite formation after 7 days of soaking in Simulated Body Fluid. Both copper ions and ibuprofen were co-released over time, showing a sustained release profile up to 14 days and 24 h, respectively, with a significantly lower burst release compared to the bare MBG particles

Phosphorylation of rat brain calpastatins by protein kinase C

AbstractCalpastatin, the natural inhibitor of calpain, is present in rat brain in multiple forms, having different molecular masses, due to the presence of one (low Mr form) or four (high Mr form) repetitive inhibitory domains. Recombinant and native calpastatin forms are substrates of protein kinase C, which phosphorylates a single serine residue at their N-terminus. Furthermore, both low and high Mr calpastatins are phosphorylated by protein kinase C at the same site. These calpastatin forms are phosphorylated also by protein kinase A, although with a lower efficiency. The incorporation of a phosphate group determines an increase in the concentration of Ca2+ required to induce the formation of the calpain-calpastatin complex. This effect results in a large decrease of the inhibitory efficiency of calpastatins. We suggest that phosphorylation of calpastatin represents a mechanism capable to balance the actual amount of active calpastatin to the level of calpain to be activated