The use of Raney's nickel in a differential assay for oxybiotin and biotin.

A method for the determination of oxybiotin in the presence of biotin in biological materials has recently been described (1). This differential assay was based upon the stability of oxybiotin towards dilute potassium permanganate and the inactivation of biotin by t.his reagent. Thii paper describes another differential assay which is based on the contrasting behavior of biotin and oxybiotin towards Raney’s nickel catalyst. Du Vigneaud et al. (2), applying the Mosingo reaction (3), have shown that biotin undergoes hydrogenolysis when treated with Raney’s nickel, and is thereby converted into desthiobiotin. It could be expected that the tetrahydrofuran moiety of oxybiotin would be resistant t,o this treatment. This was actually found to be the case. In materials containing both biotin and oxybiotin, treatment with Raney’s nickel converts the biotin into desthiobiotin without affecting the oxybiotin.l Desthiobiotin is inactive for Lactobacillus arabinosus (5). Therefore, the activity remaining after treatment with Raney’s nickel is due to the oxybiotin present. These considerations served as the basis for a quantitative method for the determination of oxybiotin in the presence of biotin. A similar procedure has already been applied by Stokes and Gunness (6) to demonstrate the conversion of desthiobiotin to biotin.