RedDot
Posts: 58
Joined: July 2007
|
| Quote (JAM @ Aug. 02 2007,01:00) | | Quote (RedDot @ Aug. 01 2007,22:36) | | The ToE demands that proteins can form naturally and spontaneously. |
No it doesn't. Modern evolutionary theories have nothing to do with your "tornado in a junkyard" BS, and the current best hypothesis for abiogenesis doesn't either.
| Quote | | Your post does nothing but prove my point. It takes very skilled biochemists, energy, and equipment to build these molecules, they will not just spring out of a petri dish. |
You don't know what you're talking about. It only takes equipment. I suspect that my requested sequence goes right from the Web form into the synthesizer without human interaction. The person running the synthesizer doesn't need to be a "very skilled biochemist" at all.
| Quote | | BTW, how many of Sigm-Aldrich's products are actual functional proteins (not merely peptides or enzymes)? |
I'll presume that you just mean the peptide synthesis group, as S-A makes thousands of chemicals.
That being said, your question makes no sense at all, as virtually all enzymes are actual functional proteins. Would you mind rephrasing it in understandable language?
| Quote | | How many of their products use only L-isomers of amino acids? |
Virtually all of their peptides do. I suspect that including D-isomers would cost extra. Are you aware that some peptides made by living things contain D isomers?
| Quote | | That's why I put "boiled" in quotation marks. I'm aiming for the cheap seats so do not make the mistake of assuming I am uninformed when I use rough analogies. |
Don't bother aiming for the cheap seats. Arguments by analogy are nearly always vapid, while in the real world, we scientists use analogies merely as explanatory devices.
And I don't have to assume that you are uninformed, because you proved that you were when you claimed that evolutionary theory requires proteins first. |
I feel like I'm in the middle of the Monty Python skit with the "Argument Office" that turns out to be only contradictions!
1) Original evolutionary theory does not mention how life originally began. So from Darwin's point of view, you are correct. Current ToE scientists and advocates (most notably the late Stephen Gould) have included abiogenesis into the overall theory. If that were not the case, no one would have much problem with ID theory or Creationists teaching school kids that God created life.
2) As for SA's products, I plan to call them and ask how they build their polypeptides, what is involved, and what their limitations are. I would also like to know what products they begin with. I suspect that they use some form of solid phase synthesis, which can be a very long, drawn out, and cumbersome process involving multiple steps, washing, cleaving, protecting chains, adding new chains, more washing, more cleaving, heating, cooling, spinning, and so forth. If they have built some kind of unmanned, automated system, I'd like to know how.
3) You are correct, I should not have typed "enzymes". Although enzymes are functional proteins, most have a simpler structure than "machine" proteins (say, transport proteins, motor proteins, hemoglobin, etc). Because they are simpler, they should be easier to build in the lab. Same with polypeptides, which often are unfolded versions of identically coded proteins. I turn your attention to Wikipedia:
Protein folding is the physical process by which a polypeptide folds into its characteristic three-dimensional structure. Each protein begins as a polypeptide, translated from a sequence of mRNA as a linear chain of amino acids. This polypeptide lacks any developed three-dimensional structure (the left hand side of the neighboring figure). However each amino acid in the chain can be thought of having certain 'gross' chemical features. These may be hydrophobic, hydrophilic, or electrically charged, for example. These interact with each other and their surroundings in the cell to produce a well-defined, three dimensional shape, the folded protein (the right hand side of the figure), known as the native state. The resulting three-dimensional structure is determined by the sequence of the amino acids. The mechanism of protein folding is not completely understood.
Experimentally determining the three dimensional structure of a protein is often very difficult and expensive. However the sequence of that protein is often known. Therefore scientists have tried to use different biophysical techniques to manually fold a protein. That is, to predict the structure of the complete protein from the sequence of the protein.
For many proteins the correct three dimensional structure is essential to function. Failure to fold into the intended shape usually produces inactive proteins with different properties (details found under prion). Several neurodegenerative and other diseases are believed to result from the accumulation of misfolded (incorrectly folded) proteins
Since we don't know a whole lot about protein folding, and cannot duplicate what cells do easily with peptide chains, I just wanted to know how many of SA's products were actually folded proteins.
3) Now it is you who do not know what you are talking about (or, to be nicer, you simply mixed up L and D isomers):
Optical Properties of the Amino Acids
A tetrahedral carbon atom with 4 distinct constituents is said to be chiral. The one amino acid not exhibiting chirality is glycine since its '"R-group" is a hydrogen atom. Chirality describes the handedness of a molecule that is observable by the ability of a molecule to rotate the plane of polarized light either to the right (dextrorotatory) or to the left (levorotatory). All of the amino acids in proteins exhibit the same absolute steric configuration as L-glyceraldehyde. Therefore, they are all L-a-amino acids. D-amino acids are never found in proteins, although they exist in nature. D-amino acids are often found in polypetide antibiotics.
From this link
|
