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What is the time taken to form a peptide bond in vivo or in vitro? It isn't mentioned in my course on protein structures. I was just curious to find out if any time scale is known?

Given that prokaryotic and eukaryotic cells have difference ribosome structures, is there any chance that the time might vary between species or even within species?

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  • $\begingroup$ Are you interested in the rate of ribosomal incorporation of amino acids into a growing polypeptide? $\endgroup$ – canadianer Jan 23 '15 at 19:06
  • $\begingroup$ Canadianer : Yes . can we without any doubt say that " the time required to link any 2 amino acids is always equal " ??? $\endgroup$ – smileandbegin Jan 23 '15 at 19:53
  • $\begingroup$ @smileandbegin I'd imagine it's strongly dependent on the cytosol concentrations of the tRNA-bound amino acids. I'm not sure what the relation between tRNA-bound amino acids and blood/cytosol unbound amino acids is, but again, I'd imagine they're to some degree proportional. That means that the time to form a bond between any two amino acids would vary based on diet, metabolism, and possibly cell type. $\endgroup$ – Watercleave Jan 25 '15 at 16:24
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Alberts et al, Molecular Biology of the Cell, say that eukaryotic ribosomes add about 2 amino acids per second, and bacterial about 20 per second (5th edition, p 275). These should be taken only as ballpark estimates: the rate certainly will vary from species to species, from cell to cell, from protein to protein. Some cells (reticulocytes, for instance) are professional protein synthesizers. Others, for instance bacterial endospores, do almost no protein synthesis at all.

These authors estimate the translation rate in mouse embryonic stem cells at around 5.5 amino acids/second. There is a lot of variation from gene to gene, even within this one cell type. They even see systematic variation depending on where you are in the gene.

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