Protein synthesis costs

In addition to the direct energy cost for the synthesis of a protein, there are indirect energy costs—those required for the cell to make the necessary enzymes for protein synthesis. Compare the magnitude of the indirect costs to a eukaryotic cell of the biosynthesis of linear (al—>4) glycogen chains and the biosynthesis of polypeptides, in terms of the enzymatic machinery involved. 

Eadie-Hofstee plot 112,114 Editing mechanisms 384-399 cost of editing 395 - 399 editing in protein synthesis 385-389... 

Scale Synthesis of chemokines on an industrial scale is theoretically possible, but so far synthesis has been successfully applied on a scale that yields about 0.1 g of pure product. This is a major limitation of the synthesis method. Consistently obtaining high yields is a potential difficulty with large scale procedures. Cost also becomes factor. So far SPPS of proteins has been used as a research tool. Native ligation technologies (15), which will not be described here, have the potential to facilitate large scale protein synthesis... 

Actidione and Anisomycin. These two anti-fungal antibiotics were tested, not because they were antibiotics, but because of their known inhibitory effects on biological systems such as those involved in protein synthesis. Both were found to be active 21) but were never pursued beyond the initial screening stages because of high cost and particularly their animal toxicity, especially to the mucosa. 

Fortunately, PKU can be easily detected in newborns, and all 50 states and the District of Columbia mandate that such a test be performed because it is cheaper to treat the disease with a modified diet than to cope with the costs of a mentally retarded individual who is usually institutionalized for life. The dietary changes are relatively simple. Phenylalanine must be limited to the amount needed for protein synthesis, and tyrosine must now be supplemented, because phenylalanine is no longer a source. You may have noticed that foods containing aspartame carry a warning about the phenylalanine portion of that artificial sweetener. A substitute for aspartame, which carries the trade name Alatame, contains alanine rather than phenylalanine. It has been introduced to retain the benefits of aspartame without the dangers associated with phenylalanine. 

Reflect and Apply What is the energy cost per amino acid in prokaryotic protein synthesis Relate this to low entropy. 

Reflect and Apply Would it be possible to calculate the cost of protein synthesis, including the cost of making mRNA and DNA ... 

Although osmo-conformation allows the clam to survive in highly saline environments, the processes of protein synthesis and repair are energy-intensive, and are estimated to cost 20%-25% of total energy expenditure under nonstressful conditions. The energy used to accumulate amino acids in response to environmental elevated salinities is not available for other survival and reproductive purposes, and probably makes the clam susceptible to succumb to other stresses. 

There is another way to compare the two probabilities. This is to compare the energy required to combine amino acids into a protein with that recovered when the protein of 99 peptide bonds is hydrolyzed to return to amino acid residues. In short, 1,618 ATP equivalents were required to form 99 peptide bonds of the 100 residue protein, which is just over 16 ATPs per peptide bond. This is a free energy cost of 8 x 16 = 128 kcal/mole. As hydrolysis of a peptide bond yields no more than 3 kcal/mole, the efficiency of energy conversion would be about 2%. Protein synthesis without considering production of the required DNA and RNA, but only the positioning of a single amino acid in the correct position, could properly be called extravagant as well. 

The above analysis reveals that the cost of growth can be divided into the individual costs of protein synthesis and degradation. We know very little about the costs of protein degradation but we are aware of the minimal costs of protein synthesis (see below) and the extent to which synthesis may be in excess of protein growth. 

---