Study on Cyanide Metabolism in Loquat by Radioisotope Tracer Method and Isotope Dilution Method

Abstract

The partially purified active fraction which metabolized cyanide in mesocarp of loquat that had been prepared as described in the previous paper was found to contain at least three enzymes. When [¹⁴C]-NaCN was used as substrate, two metabolic products were detected by papar chromatography with three solvent systems. Main peak coresponded to authentic [¹⁴C]-formate and the other coresponded to authentic [¹⁴C]-formamide.
When [¹⁴C]-formamide was used as substrate, [¹⁴C]-formate also appeared as major peak and another peak X was detected. Formate formation from formamide and peak X were diluted by non-radioactive formaldoxime, therefore X may be formaldoxime.
From these observation, it seems most likely that the following metabolic flow occurs in the mesocarp of loquat.
CN^-+H₂O→H-_??_-NH₂→(H₂C=NOH)^H₂O→HCOOH+NH₃