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2

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 ...


6

Judging from what you have said, I assume that combinatorics is not a problem to you. I believe your problem is that you think Glu-(Met)x11 is equivalent to (Met)x11-Glu, just turned around. However, that is not a correct mindset. Amino acids are not symmetrical molecules, therefore reversed linear combination does not create a turned-around (be it chiral ...


3

The individual amino acids are not symmetrical. Thus, your two example peptides are not chemically equivalent, and the $20^{12}$ figure is correct.


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Think of the amino acid choices as 12 seats. In the first seat, we have 20 choices. In the next seat, we have 20 choices, and this continues. Therefore, we have that $$ \underbrace{20\cdots 20}_{12\text{ times}} = 20^{12} $$ For your question about the the polypeptides, (Met)x11-Glu is not the same as Glu-(Met)x11, order matters. Up to this point, we ...


3

This is a guess. Tryptophan is a bulky amino acid. Having a lot of if would make the protein bulky. It is anyways hydrophobic and cannot be present on protein exteriors; high tryptophan may distort hydrophobic core possibly because of its bulkiness and ability to form pi-stacking interactions. However, tryptophan is an essential amino acid and cannot be ...


5

Yes, you can use SDS-PAGE as a semiquantitative estimate of protein concentration. You need to create a standard curve with a protein of known concentration to compare against. Quantification is done by densitometry. It's a quick and easy process, but keep in mind some limitations: Band intensity depends not only on the amount of protein but also on the ...


4

It sounds like your question is "what are the rules to protein folding?" That's not the only way to read your question. Protein Folding is a unique problem - a 1D sequence maps to a 3D object. Since proteins mediate nearly all biochemical transformations and therefore mediate life's processes, protein folding one of the great unsolved problems in ...


3

Disclaimer: This is an interesting question if I have understood what you are trying to ask. But unfortunately the case is that there are so many different cases its impossible to cover them here. Other answers talk about folding and modification, but these are still heavily dependant on the "2d" DNA sequence and aren't useful if all one has is a final ...


1

I hope that I got what are you asking. You give the example of words, it's not good one. Look on the protein like a machine or maybe cupboard. You bought one in Ikea and now you need to follow the instruction to bring together all the elements. If you just paste together all the parts you will not get a working cupboard. What rules the parts of cupboard ...


2

I'm going to assume that you mean "are there any rules for which amino acids can follow which amino acids in a protein?" The answer is no. In terms of a protein's chemistry, there is no restriction on the amino acid sequence. However, not all amino acid sequences will fold into a definite 3D structure, and not all amino acid sequences will be soluble in ...


1

I suppose you are not asking how does DNA code for mRNA which has codons (sets of 3 nucleic acids) when read in the correct reading frame (where 3 base pairs each are read beggining from the start codon) a ribosome then translates this into protein... theres a lot more details then what I said... that is called translation: ...



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