Jan H. Mozejko

Fractionation of trinucleotides from partial micrococcal nuclease digests of calf thymus DNA

Abstract The enzymic digest is first fractionated according to chain length by column chromatography on DEAE-Sephadex in 7 M urea at neutral pH. The trimer fraction is further resolved according to Gp content on DEAE-Sephadex in 50% MeOH and NH 4 -formate buffers at pH 5.2. The three subgroups of trinucleotides containing 0, 1, and 2 Gp residues, respectively, are then separated according to Ap, Cp, and Tp content on DEAE-cellulose in 7 M urea and 0.1 M formic acid. Among the 23 trimers so obtained, sequence isomers such as TpGpAp and ApGpTp are resolved by partition chromatography on cellulose columns with 30% NH 4 -sulfate at neutral pH.

Fractionation by column chromatography in aqueous methanol of partial Ustilago sphaerogena nuclease digests of RNA

The major trinucleotides in partial Ustilago sphaerogena RNase U2 digests of yeast and MS2 RNA were fractionated by column chromatography on DEAE-Sephadex or DEAE-cellulose in 7 M urea and/or in 50% methanol on DEAE-Sephadex at neutral and acid pH. The 50% methanol system at neutral pH resolved RNase T1 limit digests of RNA according to chain length up to the heptanucleotide level. Pancreatic and Ustilago ribonuclease digests were similarly fractionated up to the trimer level, not only by chain length but also according to Gp content per compound.

The basic trypsin inhibitor of bovine pancreas: X. Two-step preparation procedure☆

Abstract The method of preparation of basic pancreatic trypsin inhibitor (Kunitz) starting with the mother liquor remaining after the crystallization of trypsin (fraction E of Kunitz) has been simplified to two essential steps. In the first step the dialyzed material is passed through a Dowex 1-X2 column at pH 10. The material that passed through is composed predominantly of trypsin-trypsin inhibitor complex, which is readily crystallizable. In the second step the material from Step 1 is passed through Sephadex G-50 at pH 1.7. This separates trypsin (partially autolyzed as well as active) from the inhibitor. The latter crystallizes readily.