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Internal symmetry in this case refers to cases where a part of the protein structure can be superimposed (approximately) on another. It's not a strict mathematical symmetry, more a 'resemblance' For instance in the 12 transmembrane helix transporters, the first six helices are arranged similarly to the second six, such that if one were to cut the protein in ...


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I think you have misunderstood the "inside" part of the "positive-inside rule". Perhaps because "inside" is indeed an imprecise term (but now it is history and cannot be changed ;) ). In order to understand it a bit better it helps to think about the topology of the membrane. During synthesis most membrane proteins (ignoring peroxisomal and mitochondrial ...


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I would say impossible is a stretch. An inventive biochemist could create molecules that are "complimentary" to each amino acid similar to a Dna polymerase. Then a protein would be needed to both detect and translate this similarity into protein elongation. Unlikely, hell yes, impossible, no.


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Proteins will be digested through a number of proteases in the stomach and intestines (pepsin, trypsin, etc) into their constituent amino acids. The amino acids are then absorbed in the small intestine. So any specific proteins you try to put into a pill will be digested into amino acids before being absorbed. If you somehow manage to defeat the digestive ...


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Many proteins will pass through a 0.2 micron filter. If the proteins aggregate or if they stick to the filter material because it is charged, they may not. Barring the above, a 0.2 micron filter will allow proteins up to 200kd to pass through. There are some proteins that are larger. Editing with some source material. Nice Presentation on Pore Sizes and ...


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The residue numbering convention in the PDB is more-or-less entirely up to the depositor of the structure. While generally speaking sequential numbers are next to each other, there is no guarantee of that fact. For example, the PDB allows for what are called "insertion codes", which are extra residues which interrupt the regular sequence progression. For ...



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