Two active forms of viral-like reverse transcriptase in milk particulates from lactating Chinese women

Studies of Chinese women's milk samples indicated that the poly(rCm) oligo(dG)-directed DNA synthesis activity of milk core particulates could be separated into two distinct peaks by poly(rC)-sepharose column chromatography. Their elution positions were at 0.17-0.20 M (peak I) and 0.62-0.65 M KCl (peak II) respectively. These two enzymes differed in sedimentation rate and preference for synthetic template poly(rCm) oligo(dG). The peak I enzyme is similar to the viral type reverse transcriptase previously found in American women milk judging from the same preference for Mg⁺² as metal cation, a similar elution position at poly(rC)-sepharose column and identical sedimentation value at around 5 S. The peak II enzyme is unique in respect to its absence in American women milk core particulates. The viral origins and the relationship between these two viral-like reverse transcriptases are being investigated further.