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Denaturated proteine----> amino acid??

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Postby Dr.Stein » Tue Jul 26, 2005 11:27 am

victor wrote:That's why I can said that human is the most complicated machine that world ever have. :lol:

For digestive system, ruminants' is more complicated than human's I think... :roll:
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Postby Jokkon » Tue Aug 02, 2005 8:27 pm

HCL in our stomach denatures the proteins that we eat too, i think that makes it easier to digest too

my teacher once told us that some denaturation is sometimes reversible, the example that he used was hemoglobin, at pH 7.4 37 celcius, it bonds with oxygen in the lungs, drop o2 off in tissues when pH changes (more acidic forgot what) and 38celcius.
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Postby Dr.Stein » Wed Aug 03, 2005 2:16 am

I don't think that HCl denaturates our protein. It is needed to activate such proenzyme, it also creates an acidic environment thus enzymes can work properly, also it functions for a desinfectant.

The binding and dropping Hb molecules from HbO2 is not a denaturation process, I think.. The denaturation itself happens when it breaks protein that constructs Hb molecules into peptides or amino acids.
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Postby Jokkon » Wed Aug 03, 2005 2:20 am

yeah, HCL is used to activate pepsinogen, but since the pH in our stomach is so low, it ought to denature at least some of the proteins that we eat wouldn't it?
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Postby mith » Wed Aug 03, 2005 3:48 am

Hb surrounds the oxygen molecule a la complex ions.
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Postby victor » Wed Aug 03, 2005 10:59 am

Um, wait a minute....I think the condition is like this:
Denaturation = high temperature and high pH (alcalic).
Renaturation = low temperature and low pH (acidic).

I took it from nucleic-acid denaturation and renaturation...I think that it can be analogized with this.
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Postby Jokkon » Wed Aug 03, 2005 9:40 pm

?
i think proteins don't denature in low temperature, just that there is less kinetic NRG, therefore reactions occur slower
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Postby xand_3r » Sat Aug 06, 2005 3:34 pm

Jelanen and Poison are right: denaturation doesn't mean breaking a protein into aminoacids but altering its structure. The primary structure referes to the succession, number and nature of aminoacids while the secondary structure is determined by the intramolecular hydrogen bonds between the oxygen atom of the --C=O group and the H of the amino group ( -NH-) (the secondary structure may be a helicoidal one, resembling to that of the DNA, or a multi-layered one, when the protein is folded). The denaturation process consists in breaking the intramolecular H bonds thus altering the secondary and tertiary structure of the protein and changing their aspect and properties. For example, in our body when a protein (eg an enzyme) is denaturated it is inactive. When a protein is renaturated (the oposite of denaturation) it becomes active.
Denaturation may be reversible or irreversible. For example, reversible denaturation happens when we freeze meat or other aliments (which explains why they don't alter) or when our hair is wet it curls because of the changings in keratin structure. When the temperature rises or when the hair is dry, the protein regains its old structure. When we are boiling an egg, the albumins irreversibly change their structure, thus modifying their colour (they become white from transparent) and state of agregation (solid from liquid). The denaturation and renaturation of proteins don't occur in the same conditions like those of the DNA - they can take place at normal, freezing or boiling temperatures, under the action of gamma rays or chemical agents.
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