Biochemical heterogeneity of reverse transcriptase purified from the AIDS virus, HTLV‐III

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Abstract
The reverse transcriptase from AIDS virus, HTLV-III, was purified and characterized. The purified enzyme has a very high affinity for template primers (rC) n ·(dG)12 and (rCm) n ·(dG)12 compared to that for (rA) n ·(dT)12. In addition, the HTLV-III reverse transcriptase was able to transcribe (rAm) n ·(dT)12 very efficiently. The ionic requirements are unique in the sense that HTLV-III reverse transcriptase prefers Mg2 as divalent ions to transcribe (rC) n ·(dG)12 and (rA) n ·(dT)12. The M r of the enzyme is 95000–98000. Unlike the HTLV-I reverse transcriptase, the HTLV-III enzyme is highly stable and has a much higher activity in the presence of (rC) n ·(dG)12; the V max for HTLV-III reverse transcriptase is several-fold higher than that for HTLV-I enzyme. The enzyme activity of the purified reverse transcriptase from HTLV-III was resolved into two peaks on a preparative isoelectric column, one at pH 5.75 and the other at pH 6.25. This leads us to conclude that the reverse transcriptase of HTLV-III is biochemically heterogeneous.