Non-linear rates of acetylene reduction and concomitant H2 evolution were observed for the nitrogenase of Klebsiella pneumoniae at 10 degrees C. A lag phase of 1-4 min, dependent on the ratio of Mo-Fe protein to Fe protein present, occurred before linear rates of acetylene reduction were achieved. A complementary burst phase for concomitant H2 evolution in the presence of acetylene was also obs...

Examination of root systems and adhering soil associated with unusually green corn plants from nitrogen-deficient areas in fields has revealed higher acetylene-reducing activities than comparable root systems of chlorotic plants that appeared to be nitrogen deficient. From the root systems with acetylene-reducing activity, N(2)-fixing Enterobacter cloacae were isolated. Pure cultures of the org...

Co-adsorbed acetylene and hydrogen react on Pd(l l l ) to form ethylene and butene. Benzene is also formed and it is found that the low temperature (~ 280 K) desorption state observed on the clean surface is virtually unaffected by the presence of hydrogen whereas the higher temperature (~ 520 K) state is modified. However, adsorbing benzene onto a hydrogen pre-covered surface just affects the ...

Acetylene is a slow-binding inhibitor of the Ni- and Fe-containing dimeric hydrogenase isolated from Azotobacter vinelandii. Acetylene was released from hydrogenase during the recovery from inhibition. This indicates that no transformation of acetylene to another compound occurred as a result of the interaction with hydrogenase. However, the release of C2H2 proceeds more rapidly than the recove...

A new and extremely sensitive method for measuring nitrogenase activity through acetylene reduction is presented. Ethylene produced by nitrogenase-mediated reduction of acetylene is detected by using laser photoacoustics (LPA). This method possesses a detection limit making it 3 orders of magnitude more sensitive than traditional gas chromatographic analysis. Photoacoustic detection is based on...

The proton resonance spectra of a number of acetylenes of fixed geometry were recorded in dilute CDCl3 solution and assigned. These were acetylene, equatorialand axial-cyclohexylacetylene at 60 C, 1,4-di-1-adamantylbutadiyne, 1-ethynyl-tand -c-4-tert-butylcyclohexan-r-1-ol, 2-exo-ethynylnorbornan-2-ol† and 2,2 -ethyne-1,2diyldibornan-2-ol. The aromatic acetylenes measured were phenylacetylene, ...

A study of a single acetylene adsorbed onto the Si(100)-(2×1) surface is presented. A MCSCF+MRMP2 wave function is used to study this system, which is shown to be significantly multiconfigurational over large sections of the potential energy surface. The lowest energy isomer is shown to have the acetylene adsorbed directly above a single dimer, di-σ, where the silicon−silicon dimer bond remains...

It is well known that the addition of Ag into Pd can promote the selectivity of acetylene hydrogenation to ethylene, and early theoretical studies focus on ideal single crystal model catalysts, so it is worth studying relatively realistic catalyst models, such as metal oxide supported PdAg systems. In this work, the reaction mechanisms for acetylene selective hydrogenation on the anatase TiO2(1...

Nitrogenase activity, determined by the acetylene reduction assay, in soybean cell suspensions infected with Rhizobium, was stimulated significantly by the addition of succinic acid or glutamine. Acetylene-dependent ethylene values as high as 4.6 mumoles of ethylene/gram dry weight.hour were observed.

Aldehydes, alcohols and acids were tested for their ability to support acetylene reduction and oxygen consumption by Rhizobium japonicum bacteroids isolated from soybean nodules. Several alcohols and aldehydes increased acetylene reduction and oxygen uptake. This is consistent with the concept that the plant nodule cytosol can metabolize carbohydrate via anaerobic fermentative pathways.