New coupling mechanism of the silane coupling agents in the TATB-based PBX

Behaviours of the silane coupling agents in 1,3,5-triamino-2,4,6-trinitrobenzene (TATB)-based polymer bonded explosives (PBXs) were investigated using dissipative particle dynamics simulations. A new and extraordinary coupling mechanism of the silane coupling agent in TATB-based PBXs was revealed, in which the binding between the binders and TATB was improved by making the TATB's affinitive structure units of binders assembling at the interface, whereas the TATB's unaffinitive structure units are bonded together by the silane coupling agent shrinking into the binders. This is quite different from the traditional view, i.e. the coupling agent usually stays at the interface.     

Quantitative flux coupling analysis

Journal of Mathematical Biology - Flux coupling analysis (FCA) aims to describe the functional dependencies among reactions in a metabolic network. Currently studied coupling relations are...     

Carbon-carbon coupling in biotransformation

Most research on carbon-carbon coupling biocatalysts is still carried out on aldolases and ketolases from carbohydrate metabolism; the emphasis of these studies is on the synthesis of optically active compounds. A major target is to avoid expensive starting materials and to broaden the range of possible products. Protein engineering provides the basis not only for significant improvements of known catalysts, but also for the de novo development of new enzymes.     

Phenoloxidase catalyzed coupling of catechols. Identification of novel coupling products.

Phenoloxidases from insect cuticle as well as from other sources oxidize catechols resulting in the formation of various coupling products. The two dominating products from 4-methylcatechol and the main product from N-acetyldopamine were purified and identified by means of plasma desorption and electron impact mass spectrometry and by 1H- and 13C-NMR spectroscopy. The main product from both catechols has a quinoid trihydroxybiphenyl structure, indicating oxidative coupling between a catechol and the corresponding trihydroxy derivative. The second product from 4-methylcatechol is a biphenyltetrol derivative, indicating oxidative coupling between two catechols.     

Interaction of a coupling factor from Rhodospirillum rubrum with coupling factor deficient chromatophores

A coupling factor necessary for the photophosphorylation and Mg²⁺-ATPase activities of Rhodospirillum rubrum chromatophores has been separated from these particles. Although the redox potential of coupling factor deficient chromatophores is slightly more oxidized than of the control, the addition of the coupling factor for reconstitution does not alter the redox potential. Phenazine methosulfate cannot restore or significantly enhance the photophosphorylation activities of uncoupled or reconstituted chromatophores compared to the control. The coupling factor can bind to coupling factor deficient membranes without addition of magnesium ions and thus restore the photophosphorylation and Mg²⁺-ATPase activities of these vesicles. The Ca²⁺-ATPase in the coupling factor preparation shows binding characteristics similar to those of the coupling factor.     

Interaction of a coupling factor from Rhodospirillum rubrum with coupling factor deficient chromatophores.

A coupling factor necessary for the photophosphorylation and Mg2+-ATPase activities in Rhodospirillum rubrum chromatophores has been separated from these particles. Although the redox potential of coupling factor deficient chromatophores is slightly more oxidized than of the control, the addition of the coupling factor for reconstitution does not alter the redox potential. Phenazine methosulfate cannot restore or significantly enhance the photophosphorylation activities of uncoupled or reconstituted chromatophores compared to the control. The coupling factor can bind to coupling factor deficient membranes without addition of magnesium ions and thus restore the photophosphorylation and Mg2+-ATPase activities of these vesicles. The Ca2+-ATPase in the coupling factor preparation shows binding characteristics similar to those of the coupling factor.     

Kinetic analysis of excitation-contraction coupling

Recent studies of isolated muscle membrane have enabled induction and monitoring of rapid Ca²⁺ release from sarcoplasmic reticulum (SR)⁵ in vitro by a variety of methods. On the other hand, various proteins that may be directly or indirectly involved in the Ca²⁺ release mechanism have begun to be unveiled. In this mini-review, we attempt to deduce the molecular mechanism by which Ca²⁺ release is induced, regulated, and performed, by combining the updated information of the Ca²⁺ release kinetics with the accumulated knowledge about the key molecular components.Abbreviations used: AMP-PCP, adenosine 5-(, -methylenetriphosphate); C_1/2, concentration a half-maximal activation or inhibition; Con-A, concanavalin A; DACM,N-(7-dimethylamino-4-methyl-3-coumarinyl)maleimide; DCCD, dicyclohexylcarbodiimide; SR, sarcoplasmic reticulum; DHP, dihydropyridine; E-C, excitation-contraction; EP, phosphorylated intermediate of the enzyme; IP₃, inositol 1,4,5-trisphosphate; JFM, junctional face membrane;M _r, molecular weight; T-tubule, transverse-tubular system.