Catalytic activity of the nucleic acid component of the 1,4-alpha-glucan branching enzyme from rabbit muscles

2.5 S RNA, the nucleic acid component of the 1,4-alpha-D-glucan: 1,4-alpha-D-glucan 6-alpha-(1,4-alpha-glucano)-transferase from rabbit muscles, devoid of any protein, catalyses the branching reaction, as does the holoenzyme. The conclusion is drawn that 2.5 S RNA is a ribozyme. To get an insight into the significance of different parts of the molecule for the catalytic activity of 2.5 S RNA, a large fragment isolated from its partial RNAase A digest was investigated. This fragment which proved to be the middle part of polyribonucleotide chain containing all modified nucleotides exerts some catalytic activity, too.