A relatively recent technique termed comprehensive multiphase (CMP) NMR spectroscopy was used to investigate the growth and associated metabolomic changes of C-labeled wheat seeds and germinated seedlings. CMP-NMR enables the study of all phases in intact samples (i.e., liquid, gel-like, semisolid, and solid), by combining all required electronics into a single NMR probe, and can be used for investigating biological processes such as seed germination. All components, from the most liquid-like (i.e., dissolved metabolites) to the most rigid or solid-like (seed coat) were monitored in situ over 4 days. A wide range of metabolites were identified, and after 96 h of germination, the number of metabolites in the mobile phase more than doubled in comparison to 0 h (dry seed). This work represents the first application of CMP-NMR to follow biological processes in plants.
Seeds are complex entities composed of liquids, gels, and solids. NMR spectroscopy is a powerful tool for studying molecular structure but has evolved into two fields, solution and solid state. Comprehensive multiphase (CMP) NMR spectroscopy is capable of liquid-, gel-, and solid-state experiments for studying intact samples where all organic components are studied and differentiated in situ. Herein, intact (13)C-labeled seeds were studied by a variety of 1D/2D (1)H/(13)C experiments. In the mobile phase, an assortment of metabolites in a single (13)C-labeled wheat seed were identified; the gel phase was dominated by triacylglycerides; the semisolid phase was composed largely of carbohydrate biopolymers, and the solid phase was greatly influenced by starchy endosperm signals. Subsequently, the seeds were compared and relative similarities and differences between seed types discussed. This study represents the first application of CMP-NMR to food chemistry and demonstrates its general utility and feasibility for studying intact heterogeneous samples.
On the other hand, these results demonstrate that plasma tends to maintain a rather steady vitamin A alcohol level. Although this mechanism is still unknown, one possible explanation is that the plasma concentration is dependent upon the degree of association of vitamin A alcohol with a protein carrier. Variations in this degree of association may explain the temporary increase in plasma vitamin A alcohol immediately following absorption ofvitamin A. The sharp increase in the ester form of vitamin A during active absorption may likewise be due to its association with another protein. SUMMARY1. The rate of appearance of vitamin A ester and alcohol in plasma and liver, respectively, of vitamin A-depleted male rats following a single dose of vitamin A was studied. In plasma, the ester form I953 Vol. 54 ACETYLATION OF COLLAGEN 187 SUMMARY 1. Inmildlyalkaline suspension collagenis acetylated by acetic anhydride at the free amino groups. The number of N-acetyl groups introduced is equal to the total number of lysine and hydroxylysine residues found by analysis.2. Dry collagen does not react with cold acetic anhydride, but in the presence of acetic acid or of small amounts of water both N-and O-acetylation take place.3. The reaction is a slow one and is catalysed by acetic acid or, indirectly, bywater. At its completion all the E-amino groups and about 77 % of the hydroxyamino-acid residues of the protein have reacted.One of Us (L.C.L.) was the holder of a Shell Research Fellowship during the session 1950-51, andgratefulaoknowledgement is made to the Shell Company of Singapore, Ltd., for their assistance. We also thank Prof. R. A. Robinson for valuable advice.
The amyloid-b (Ab) aggregation pathway is an important target for the discovery of drugs that can prevent or delay the onset of Alzheimers disease (AD). The electrochemistry of Congo Red (CR) represents a particularly promising tool for screening of Ab-binding therapeutics in a rapid and cost-effective format. The results of the differential pulse voltammetry (DPV) measurements were confirmed using simultaneous UV-vis analysis of the same incubated Ab samples. The early changes in the electrochemical signals were attributed to the interaction of the Ab oligomers with CR. The electrochemical approach, in principle, allowed monitoring small molecule-Ab interactions on the time scale of aggregation.
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