Nitrile hydratase recombinant from E.coli

Density

Link to relevant study record(s)

Reference

Endpoint:

relative density

Data waiving:

study technically not feasible

Justification for data waiving:

the study does not need to be conducted because the substance is only stable in solution in a particular solvent and the solution density is similar to that of the solvent

Description of key information

In accordance with REACH Annex XI, section 2, a density study is not required as testing is technically not possible as a consequence of the properties of the substance.

The substance, nitrile hydratase, is a substance that is handled in a state where a mixture of the enzyme and the dead bacteria that produced it is dispersed in water.

A fundamental requirement for testing the physicochemical properties of a substance, is that the substance is tested as such, excluding all solvents. However, since the higher order structure of the constituent molecules of the proposed substance (nitrile hydratase) is damaged by the removal of water, it cannot be said that the proposed substance would be correctly evaluated by performing this test after the removal of water. It should therefore be avoided.

In order to avoid deterioration it would be possible to conduct the test by leaving the substance as a suspension (ie dispersed in water). However, to do so would render the test results meaningless as the physical properties of water would greatly influence the results of such a test. As such it is technically impossible to obtain a meaningful result.