Question

A newly developed antibiotic drug shows promise by inhibiting prokaryotic 70S ribosomes in initial studies. However, when animal studies are begun, it's noted that it also inhibits the growth of animal cells. Aren't prokaryotic ribosomes different from eukaryotic ribosomes? How can this be happening? Give two possible explanations.

Answer 1

The two hypotheses are:

1. The antibiotic has affinity with mitochondrial ribosomes.

Mitochondrial ribosomes may have a region similar to prokaryotic ribosomes, given their similarities. So the molecules will bind to share on prokaryotic and mitochondrial mitochondria.

2. The antibiotic has low affinity with eukaryotic ribosomes.

Despite the difference between ribosomes 70S and 80S, it may be quite similar for the antiobiotic to find a binding site at the low affinity 80S ribosome. The antibiotic binds preferentially to the 70S ribosomes, but when there is a saturation of the binding sites on the 70S ribosomes, the excess of the antibiotic molecules will then bind to the 80S ribosomes.