The effects of method of protein extraction on ribosomal function in vitro. Ribosomes from the bacterium Thermus aquaticus were treated with the detergent sodium dodecyl sulfate (SDS), the enzyme proteinase K, or phenol, then tested for peptidyl transferase activity using the fragment reaction. The product of the reaction, [35S]fMet-puromycin, was assayed by paper electrophoresis and autoradiography. (fMet is N-formylmethionine, the initiating amino acid in bacterial protein synthesis, described later in this chapter.)