Several model systems have been used to study transpeptidation on ribosomes. The reaction of puromycin with numerous derivatives of aminoacyl-tRNA as synthetic donors has provided the basis for most model systems. Common synthetic donors have included fMettRNA, acetyl-Phe-tRNA, polylysyl-tRNA, and fragments of tRNA such as C-A-C-C-A (Ac-Phe) and C-A-A-C-C-A(fMet). The ribosomes used generally have been washed in 1 M NH4CI, although ribosomes washed in low salt have also been used. Because of apparent disparate results of inhibitors on peptide bond synthesis in model systems and intact cells, it was useful to study transpeptidation in a more nearly physiological system, which behaved similarly to the process in intact cells. For this reason, native polyribosomes have been prepared and used as the enzyme-substrate complex containing peptidyl-tRNA. © 1974, Elsevier Inc. All rights reserved.
Pestka, S. (1974).  Peptidyl-Puromycin Synthesis on Polyribosomes from Escherichia coli. Methods in Enzymology, 30(C), 470–479. https://doi.org/10.1016/0076-6879(74)30047-X