Measurement of nitrogenase activity, Biology

Measurement of Nitrogenase Activity

There are various methods to find out whether an organism is a N2-fixer or not. If an organism can grow in normal atmosphere without any provision of a nitrogen source like nitrate or ammonia, one infers the organism to be a N2-fixer. It is important to mention here that N2-fixer heterocysts cyanobacteria or Rhizobium-legume system are known to grow without any supply of fixed nitrogen. The other more reliable method is the incorporation of 15N isotope into cellular nitrogen containing compound which can be estimated in a mass spectrometer. This method is very costly and is, therefore, not easily accessible for day-to-day measurement of nitrogenase activity and N,-fixation. The most extensively used method for measuring nitrogenase activity is the acetylene reduction method. The method consists of incubating the N2-fixing system with about 10% acetylene for a period of 10 to 30 min during which nitrogenase converts acetylene into ethylene depending on its efficiency.

Gas samples are then taken out by syringe from the reaction sample and the acetylene reduced is assayed by injecting the gas sample into a gas chromatograph which separates quantitatively acetylene and ethylene and thus provides easy quantitative assay of ethylene. Nitrogenase catalysed reduction of acetylene to ethylene is not accompanied by reduction of proton to molecular hydrogen as happens in the reduction of N2 to NH­3. The reduction of acetylene to ethylene involves two electrons and if one wants to equate the amount of ethylene produced with the amount of N2 fixed then the amount of ethylene has to be divided by a factor of 4 to find out the optimum level of N2-fixing activity of nitrogenase.

Posted Date: 1/17/2013 5:16:21 AM | Location : United States







Related Discussions:- Measurement of nitrogenase activity, Assignment Help, Ask Question on Measurement of nitrogenase activity, Get Answer, Expert's Help, Measurement of nitrogenase activity Discussions

Write discussion on Measurement of nitrogenase activity
Your posts are moderated
Related Questions
Explain transports of substances or materials in the membrane by the help of Lipid-anchored proteins with examles

Using examples of invertebrate nervous systems how can the process of evolutionary cephalization be described? Considering the instance of invertebrates it is observed that ev

Ovule The ovule, also known as the megasporangium is the forerunner of the seed. It consists of a central mound of tissue called the nucellus, which is enveloped by one or tw

classification of phylum protozoa upto groups

What is the mode of nutrition in fish,human,amoeba,scorpian & toad

Q. Is the stage when an insect larva is within a cocoon a stage of total biological inactivity? The period when the larva is inside its cocoon is a time of intense biological a

Secondary Growth in a Typical Dicotyledonous Stem In stem, the secondary growth in thickness in diameter is confined both intrastelar, i.e., in the stele and extrastelar regio

Explain the Skin fold method to measure body fats? The skin fold method utilizes predication of body fat from sum of three or four skin folds (at biceps, triceps, sub scapular,

Q. What is an example of intraspecific competition? The Intraspecific competition occurs in practically all species, for instance, the competition of humans for a job.

mentions chareacteristics and classificaton of protozoa?