C-nuclear magnetic resonance studies of 85% C-enriched amino acids and small peptides: pH effects on the chemical shifts, coupling constants, kinetics of cis-trans isomerisation and conformation aspects

The ¹³C chemical shifts of several 85% ¹³C-enriched amino acids and small peptides were studied as a function of pH. The results show that the chemical shifts of carbon atoms of ionizable groups vary significantly within the zone of their pK. Generally with the pH going from 7 to 1 all the δC are shifted more or less upfield with the exception of the carbonyl group of the second last residue which is shifted slightly downfield. This suggests the formation of an hydrogen bond at acid pH involving in a seven-membered ring the C=O in question and the COOH terminal.The percentage of cis and trans conformers of glycyl-l-proline and glycyl-l-prolylglycine were studied as a function of pH. The trans form is always preponderant whatever the pH. The accessibility of the carbonyl group to protonation of the proline residue strongly influences the cis-trans equilibrium. Thus, with the pH varying from 7 to 1, the trans isomer changes from 61 to 85% for glycyl-l-proline and only from 77 to 80% for glycyl-l-prolylglycine.The proton NMR studies underline the important differences existing between the two molecular forms of glycyl-l-proline. The cis conformation is characterized with regard to the trans form by the non-equivalence of the α-protons of the glycine residue, by a lower pK₁ and by a larger ΔδH_α of the proline residue as a function of pH. These results could suggest an end-to-end interaction in the cis form of the glycyl-l-proline molecule.The ¹³C-¹³C coupling constants were also studied as a function of pH. The results show that J_Co-Cα of a C-terminal residue, varying from 5 to 6 Hz and reflecting the pK of the carboxylate group, is a linear function of δ_Co and δ_Cα as in the case of the amino acids. The total variation of the electron density of those two carbons in an amino acid is approximately 40% weaker than in a C-terminal residue. The charge distribution along the C_α−C_o bond, however, is practically the same in both cases.Finally the ratios of the conversion rate constants of the two isomers cis-trans of glycyl-proline were calculated at different pH values; the relations between the isomer percentages and δ_Co, δ_Cα on the one hand and the J_Co-Cα on the other were established.     

Differential inactivation of plant lauric acid omega- and in-chain-hydroxylases by terminally unsaturated fatty acids

The microsomal fraction from Vicia sativa L. cv. Septimane contains a cytochrome P-450-dependent lauric acid omega-hydroxylase that is inactivated in a time-dependent, pseudo-first-order manner when the microsomes are incubated with 11-dodecynoic acid. The rate constant for the inactivation is approximately 4.3-4.8 X 10(-3) s-1. In contrast, the olefinic analog 11-dodecenoic acid is primarily a time-independent inhibitor of the omega-hydroxylase. 1-Aminobenzotriazole, 3-phenoxy-1-propyne, and 3-(2,4-dichlorophenoxy)-1-propyne, mechanism-based inactivators of cinnamic acid 4-hydroxylase, and 9-decenoic acid, a mechanism-based inactivator of the lauric acid in-chain hydroxylase, are at best poor inactivators of the omega-hydroxylase. Conversely, cinnamic acid 4-hydroxylase is only slightly affected by concentrations of 11-dodecynoic acid that completely inactivate the omega-hydroxylase. 11-Dodecynoic acid is thus a potent, relatively specific, inactivator of the V. sativa lauric acid omega-hydroxylase.     

Environmental impacts of household goods in Europe: a process-based life cycle assessment model to assess consumption footprint

The International Journal of Life Cycle Assessment - Current patterns of household goods consumption generate relevant environmental pressures and impacts. Environmental impacts are not only...     

Correction to: The evolution of life cycle assessment in european policies over three decades

The International Journal of Life Cycle Assessment -     

Assunzione di Fosforo32 da Parte di Cuscuta Epithymum Parassita di Trifolium Repens

Abstract

Uptake of Phosporus-P³² by CUSCUTA EPITHYMUM parasitic of TRIFOLIUM REPENS. — Filaments of C. epithymum, parasitic on T. repens, partially immersed in a solution containing KH₂P³²O₄, uptake from the host solely, or mainly, radioactive ortophosphate. Radioactive hexose phosphates and radioactive nucleotides present in the extracts prepared from C. epithymum, appear to be the result of the metabolization by the dodder of the orthophosphate uptaken from the host.     

Ambiguous Base Pairing of 1-(2-Deoxy-β-D-Ribofuranosyl)imidazole-4-carboxamide During PCR

Abstract

The use of 5′-triphosphate of 1-(2-deoxy-β-D-ribofuranosyl)imidazole-4-carboxamide (dYTP) in DNA amplification reaction in place of dATP or dGTP yielded mutations frequencies of 3–4×10^?2 per base per amplification. A reasonable proportion of transversions (11–15%) was observed in the absence of deletions and insertions.     

EV20, a Novel Anti-ErbB-3 Humanized Antibody,Promotes ErbB-3 Down-Regulation and Inhibits Tumor Growth In Vivo

ErbB-3 (HER-3) receptor is involved in tumor progression and resistance to therapy. Development of specific inhibitors impairing the activity of ErbB-3 is an attractive tool for cancer therapeutics. MP-RM-1, a murine monoclonal antibody targeting human ErbB-3, has shown anticancer activity in preclinical models. With the aim to provide novel candidates for clinical use, we have successfully generated a humanized version of MP-RM-1. The humanized antibody, named EV20, abrogates both ligand-dependent and ligand-independent receptor signaling of several tumor cell types, strongly promotes ErbB-3 down-regulation, and efficiently and rapidly internalizes into tumor cells. Furthermore, treatment with EV20 significantly inhibits growth of xenografts originating from prostatic, ovarian, and pancreatic cancers as well as melanoma in nude mice. In conclusion, we provide a novel candidate for ErbB-3-targeted cancer therapy.     

The Puzzle of Italian Rice Origin and Evolution: Determining Genetic Divergence and Affinity of Rice Germplasm from Italy and Asia

The characterization of genetic divergence and relationships of a set of germplasm is essential for its efficient applications in crop breeding and understanding of the origin/evolution of crop varieties from a given geographical region. As the largest rice producing country in Europe, Italy holds rice germplasm with abundant genetic diversity. Although Italian rice varieties and the traditional ones in particular have played important roles in rice production and breeding, knowledge concerning the origin and evolution of Italian traditional varieties is still limited. To solve the puzzle of Italian rice origin, we characterized genetic divergence and relationships of 348 rice varieties from Italy and Asia based on the polymorphisms of microsatellite fingerprints. We also included common wild rice O. rufipogon as a reference in the characterization. Results indicated relatively rich genetic diversity (H _e = 0.63-0.65) in Italian rice varieties. Further analyses revealed a close genetic relationship of the Italian traditional varieties with those from northern China, which provides strong genetic evidence for tracing the possible origin of early established rice varieties in Italy. These findings have significant implications for the rice breeding programs, in which appropriate germplasm can be selected from a given region and utilized for transferring unique genetic traits based on its genetic diversity and evolutionary relationships.