Enkephalin-like products in embryonic chicken retina

Using sensitive and highly specific radioimmunoassays, Met-enkephalin (Met-ENK) and Leu-enkephalin (Leu-ENK) have been shown to exist together in the retina of chicken embryo. After high performance liquid chromatography (HPLC), a fraction of the retinal extracts seems to be authentic Met-ENK. Following a G-50 filtration, the Met-ENK immunoreactivity has been found associated to three peaks, the lightest having an apparent molecular weight similar to that of the Met-ENK.