I recently read an article that talked about hemoglobin being discovered in dinosaur bones. The bones are said to be 80 million years old. I'm just wondering how long hemoglobin can last in an animal thats dead and become fossilized. Is it possible that it could last for 80 million years?
Apparently a long time. I don't know anything about the chemical involved. You'd need to understand how it reacts to heat and other chemicals to know how stable it might be.
What we can say is that some chemicals (calcium carbonate for example) are very stable under pretty common conditions and others (DNA for example) only moderately stable for a much shorter period of time while still others aren't going to last days even. Where heme falls in this range I don't know other than there are some suggesting that it can hang together for 10's of millions of years.
The technique they used in the experiment involved raising antibodies to whatever bits of hemoglobin were left. Creation of antibodies in this way doesn't require that any functional protein or protein pieces remain, since very small fragments will work. (I'm not even sure they specifically stated intact heme was there, though they showed a diagram of it, I think...)
I'm not sure how long protein fragments would last - apparently this was a rare finding, so it might be a matter of just the right fossilization conditions and a lot of luck...
Like most claims of detection of ancient biomolecules in the millions of years old range, I am extremely skeptical of this one. The amber DNA studies for example were never reproducible and in the case of one, it was discovered to be an artifact (if not fraud).
Gutierrez G, Marin A. The most ancient DNA recovered from an amber-preserved specimen may not be as ancient as it seems. Mol Biol Evol. 1998 Jul;15(7):926-9.
In any case, the presence of intact and detectable (using antibodies) heme compounds from an 80 My old fossil sounds more like contamination of the fossil than authentic endogenous protein breakdown products. If you look at the best studied ancient proteins they come from mammoths that were only several tens of thousands of years old and the amount of endogenous protein detected was about 2% of what you would expect for a modern sample.
Science. 1980 Jul 11;209(4453):287-9. Related Articles, Links
Prager EM, Wilson AC, Lowenstein JM, Sarich VM.
Serum albumin was detected immunologically in muscle from a mammoth that died about 40,000 years ago. Rabbits injected with ground mammoth muscle produced antibodies that react strongly with elephant albumin, weakly with sea cow albumin, and still more weakly or not at all with other mammalian albumins. Since elephant albumin elicited antibodies with the same specificity, some of the surviving mammoth albumin molecules evidently have antigenic sites identical to those on native elephant albumin. Much of the mammoth albumin has, however, undergone postmortem change. The small amount of soluble albumin extractable from mammoth muscle is heterogeneous in size, charge, and antigenic properties.
It is hard to imagine that an 80 My old fossil would show preservation anywhere in the range of a permafrost frozen specimen like the Dima mammoth which is only about 40 Ky old. So until the dinosaur data is independently reproduced I for one would list it as a highly tentative result given the frequency with which these types of experiments tend to turn out false.
Hi Mammuthus, Actually I think that the evidence for the protein degradation products is pretty strong. The leg bones were capped (I believe that is the correct word for when the ends of a long bone fossilizes) maintaining the integrity of the interior portion. Also the presence of the calcium phosphate matrix has a tendency to stabilize proteins, essentially it is a hydroxyapatite matrix which is known to bind proteins, dome with a very high affinity. The protein was old enough for recemization to have occurred, a process that was probably slowed by the binding of the degradation products to the mineral matrix, check this out for a small amount of supporting data for stability.
As mentioned above, there have been a number of reports concerning the preservation of osteocalcin indicated both by fragments capable of generating an immune response and the presence of remnants of the modified amino acid g-carboxyglutamic acid.One of the references is Preservation of the Bone Protein Osteocalcin in Dinosaurs Geology, Vol. 20, October 1992, pages 871-874. I will try to find a couple of the other ones that I have at home.
While not much is required in the way of the linear epitopes required for the generation antibodies, the racemization actually may have increased the immunogenicity. I do not have much info in that regard, but the lack of a reaction from the surrounding tissues and samples is indicative that the results were real.
"Chance favors the prepared mind." L. Pasteur and my family motto Transfixus sed non mortis Taz
For those interested, here is the abstract and link to the actual primary literature on the find:
Proc Natl Acad Sci U S A. 1997 Jun 10;94(12):6291-6. Heme compounds in dinosaur trabecular bone.
Schweitzer MH, Marshall M, Carron K, Bohle DS, Busse SC, Arnold EV, Barnard D, Horner JR, Starkey JR.
Department of Biology and Museum of the Rockies, Montana State University, Bozeman, MT 59717, USA.
Six independent lines of evidence point to the existence of heme-containing compounds and/or hemoglobin breakdown products in extracts of trabecular tissues of the large theropod dinosaur Tyrannosaurus rex. These include signatures from nuclear magnetic resonance and electron spin resonance that indicate the presence of a paramagnetic compound consistent with heme. In addition, UV/visible spectroscopy and high performance liquid chromatography data are consistent with the Soret absorbance characteristic of this molecule. Resonance Raman profiles are also consistent with a modified heme structure. Finally, when dinosaurian tissues were extracted for protein fragments and were used to immunize rats, the resulting antisera reacted positively with purified avian and mammalian hemoglobins. The most parsimonious explanation of this evidence is the presence of blood-derived hemoglobin compounds preserved in the dinosaurian tissues.
It would seem to me that they did indeed find heme. But like other discussions on ancient protein/DNA, contamination is a real possibility. However, they did control for it.
"Significant levels of D-enantiomers of individual amino acids (39) suggest that the source proteins are ancient. Considering the rapid burial and geological sequestration of the skeleton, as well as excellent microstructural preservation (39), the most likely source of these proteins is the once-living cells of the dinosaur. This is supported by the lack of signal from either embedding sandstone or plant material extracted in the same manner as the bone tissues in various analytical examinations."
This message has been edited by Loudmouth, 06-23-2004 03:25 PM
Hi Loudmouth, I actually have had a reprint of the paper since shortly after it came out. . What interests me the most is the relationship between the tissue where the degraded proteins are found and the chemistry of stabilization. I have been using hydroxyapatite for years as a purification matrix and have found that it can also be used to bind protiens and hold them in a stable form in a liquid formulation much longer than can normally be expected in a standard liquid formulation. Activity and structure are often held stable over substantial periods (substantial for a protein biologic anyway). As part of my work currently revolves around determining the stability of my biologics this was obviously of a great deal of interest to me. It was not until I read about this and other bone proteins from fossils that I started to consider other implacations, re: protein fragments from fossils.
This message has been edited by Dr_Tazimus_maximus, 06-23-2004 10:46 PM
"Chance favors the prepared mind." L. Pasteur and my family motto Transfixus sed non mortis Taz
Hi Taz, Great to see you back on the forum! Protein racemization levels do seem to correlate with DNA preservation in ancient materials (won't call them fossils since they are not fossilized). However, this is on a scale of tens of thousands of years and not millions. The amber studies demonstrated reasonably low racemization levels for the amber inclusions yet without an exception, none of the DNA results could be reproduced and the reference I include implies something a bit more sinister for one of the participating groups. That aside, having worked in a museum for a few years, the fossils get handled A LOT. In addition, many are treated with various preservatives, paints, etc. many of which are organic based or include animal/insect proteins. It is still formally possible that the immune reaction was generated by a contaminant of the handled fossil as opposed to endogenous protein residue. Another cautionary note, the biggest fiasco in ancient DNA was the report of DNA sequences from a dinosaur bone. It turned out to be a human nuclear insertion copy of mitochondrial cytochrome b. Even though fairly stringent controls were observed. I recognize that proteins can be much more stable than nucleic acids. I am currently working with prions and you cannot get rid of the damn things. But 80 My proteins will necessarily require an extreme burden of proof.
I too use hydroxyapatite for purification, but I have never considered using it for protein stabilization over extended periods. HPT has sort of lost favor over the years, but I love the stuff. Instead of a simple anion/cation exchange group it uses a complex crystal structure which contains both positive and negative groups. It's great for separating proteins of similar pI that have previously undergone separation under isoelectric focusing or simple anion/cation exchange. I am lucky enough to be able to freeze back my proteins in a 20% glycerol solution, but thanks for the info anyway.
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