Reduction acetylene

Acetylene-reduction assay Estimates nitrogenase activity by measuring the rate of acetylene reduced to ethylene. 

MeNHNH2. This reagent was used to prevent diimide formation, which resulted in acetylene reduction." ... 

There are reports (reviewed in Ref. (55)) of acetylene reduction by FeMoco using very powerful reductants such as sodium borohydride or sodium amalgam. Unfortunately, in most of these experiments the integrity of FeMoco after reaction was not established, and thus the reaction could have been carried out by fragments of FeMoco. Reduction of acetylene bound to a metal site by powerful reductants is well established. 

As noted previously, FeVaco can be extracted from AcF by the methods used to extract FeMoco from MoFe proteins (777). When FeVaco was combined with the polypeptides of the MoFe proteins from a nifB mutant, an active hybrid protein was created. However, although this protein had the H2 evolution and acetylene reduction... 

Substrate reduction by the iron nitrogenase is very similar to that observed with vanadium nitrogenases. Acetylene is a relatively poor substrate, and N2 reduction is accompanied by considerable H2 evolution. Acetylene reduction leads to the production of some ethane as well as ethylene. Beyond this, little has been investigated. Under optimal conditions for N2 reduction, the ratio of N2 reduced to H2 produced was 1 7.5 compared with 1 1 for molybdenum nitrogenase 192). 

A. A. Tsygankov, L. T. Serebryakova, K. K. Rao, D. O. Hall (1998) Acetylene reduction and hydrogen photoproduction by wild type and mutant of Anabaena at different CO2 and O2 concentrations.FEMS Microbiol. Lett., 167 13-17. 

Burris, R.H. The acetylene reduction technique. In Nitrogen Fixation by Free-living Micro-organisms, VoL 6, W.D.P. Stewart,... 

The development of the acetylene reduction assay to measure nitrogenase activity. 

This new assay technique was developed independently by American and Australian workers who first established the connection between nitrogenase and hydrogenase, and showed the former could reduce a number of substrates other than nitrogen, for example nitrous oxide, azide, cyanide and, most usefully, acetylene. The latter is reduced to ethylene and this forms the basis of the acetylene reduction test. The material to be examined is briefly gassed with acetylene and the ethylene formed measured by gas chromatography. While this technique was being refined,... 

Burris, R.H. (1975). The acetylene-reduction technique. Nitrogen fixation by free-living microorganisms. The International Biological Programme 6, 249-257. 

Capone, D.G. (1982) Nitrogen fixation (acetylene reduction) by rhizosphere sediments of the eelgrass Zostera marina. Mar. Ecol. Prog. Ser. 10, 67-75. 

Hanson, R.B. (1983) Nitrogen fixation activity (acetylene reduction) in the rhizosphere of a salt marsh angiosperm, Georgia, USA. Bot. Mar. 26, 49-59. 

Newell, S.Y., Hopkinson, C.S., and Scott, L.A., (1992) Patterns of nitrogenase activity (acetylene reduction) associated with standing, decaying shoots of Spartina altemiflora. Estuar. Coastal Shelf Sci. 35, 127-140. 

These reaction mixtures still are not well understood. For example, the initial reports (87) state (i) that while the thiol group was important, the organic residue to which it was attached had only minor effects and (ii) that ethylene was the major product of acetylene reduction. A recent reinvestigation (92) shows (i) that methyl groups... 

Acetylene Reduction and Electron Spin Resonance Characteristics... 

Table I. Acetylene Reduction by Mo-Complex Systems of Cysteine and Its Related Ligands0...

Table II. Catalytic Activity of Various Molybdothiol and Molybdoselenol Complex Catalysts in Acetylene Reduction...

Table V. Effect of Amino-Acid Residues on Acetylene Reduction...

Figure 2. The cocatalytic effects of various charge carriers on acetylene reduction by the Mo(V)-cysteine complex (0.42 mmol) and NaBH4 (1.0 mmol), plotted against the reduction potentials (V vs. SHE) of the corresponding additives.

---