Why non-denatured protein?

[rapidgrowth]

I'm just posting this because the info I've been finding isn't making sense to me. I'll list my point. (p.s. this is info that I found i'm not making it up so please don't freak out on me because I dont' know something you do)

Point #1. Protein is a chain of amino acids. These amino-acid strings fold back on themselves (the way the strings fold determines the protein's chemical and biological properties). The proteins are held in place by weak bonds (non-covalent) between different parts of the amino-acid string. When you break those strings, by various methods, you are denaturing the protein.

Point #2. Denatured- Denaturing occurs when protein is exposed to high temperatures (typically over 60 degrees Celsius) or to certain chemicals that disrupt the protein structures. After this change the protein can no longer perform its biological function. (Starr and Taggart, 1987.58) This is why you should look for undenatured types of protein.

Okay, if above is true then here's where I get a little confused.

Point #3. The proteins, in its original form, are too large to be absorbed through the intestines. The body breaks them down into smaller components called amino acids. The amino acids are small enough to penetrate the intestinal wall and are absorbed into the blood stream.

Point #4. Steps of Protein Digestion
A. Mouth
- reduce particle size to increase surface area
B. Stomach
1. HCl
- reduces pH to 2-3
- disrupts hydrogen bonds & DENATURES protein
2. Pepsin
- secreted by gastric mucosa (chief cells)
- breaks down DENATURED protein
- cleavage of protein at specific AA – aromatic
- breaks peptide bonds
*following steps left out but can include if you want to see them*

Okay, according to Point #3 Proteins are broken down into amino acids and absorbed into the blood stream through the intestinal wall. Intestinal processing takes place after stomach processing, and point #4 states that the HCL in the stomach DENATURES the protein! So what I am getting from this is before you absorb any benefits from the protein it becomes denatured. Therefore leading me to ask... what is the importance of buying non-denatured protein if your stomach is going to denature it before you absorb it anyway?

[MushMouth]

Your stomach does not denature the protein. The digestive process is hydrolysis which leaves it biologically active.

At least, thats what I thought.

[rapidgrowth]

I just searched with keywords, denature protein digestion, on google to try and find more support for what I was saying. Immediatly info came up that said
Gastric juice, 2-5% HCl, pH1.0 denature proteins
so... ? I don't know, i'm just trying to make sense of the non-denatured emphasis.

[MushMouth]

Ok, I think I get it now. The protein is denatured to a point that it allows the enzymes to work on it, but not to a point that its biologically inactive.

[rapidgrowth]

I'm under the impression that it is either denatured or not. I don't see how it could be somewhat denatured since denaturing has to do with breaking bonds. If the bond is broken then = denatured... if not then its not denatured right?

[MushMouth]

Hopefully someone who's got some experience in biochemistry will chime in soon, but denaturing of protein doesn't break the bonds, its unfolds the structure. Hydrolysis is what breaks the bond. Or something like that.

[ManOfSteel2003]

Denaturing of proteins isn't always bad. When the albumin in an egg white is denatured by cooking, it turns from a liquid to a solid because some of the hydrogen bonding is being broken down (like said above, but this isn't causing relevant deamination for the bodies utilization). This doesn't make the protein useless, now does it? Unless the cooking was excessive (thus rendering the chains of amino acids destroyed along with the amino acids themselves), the proteins will still be able to be utilized in the body. Then, through digestion (by means of the enzymes pepsin, trypsin, chymotrypsin, and pepsidase, the body breaks down the proteins further into amino acids which are used by the body's cells.

[ManOfSteel2003]

Originally posted by MushMouth
Hopefully someone who's got some experience in biochemistry will chime in soon, but denaturing of protein doesn't break the bonds, its unfolds the structure. Hydrolysis is what breaks the bond. Or something like that.

Hydrogen bond breaking is what denaturing of protein is, of course it is broken. The heat shouldn't be causing hydrolysis.

[MushMouth]

Originally posted by ManOfSteel2003
Hydrogen bond breaking is what denaturing of protein is, of course it is broken. The heat shouldn't be causing hydrolysis.

I was referring to peptide bonds. These have to be broken by hydrolysis.

[ManOfSteel2003]

Originally posted by MushMouth
I was referring to peptide bonds. These have to be broken by hydrolysis.

Yeah, which will occur inside the body during digestion, not by cooking. What isn't understood here, I'm confused?

[MushMouth]

Originally posted by ManOfSteel2003
Yeah, which will occur inside the body during digestion, not by cooking. What isn't understood here, I'm confused?

He was talking about digestion, and why it was different from denaturing food by heat. When he said that denaturing breaks the bonds, I thought he meant the peptide bonds, and hence my answer that the bonds had to be broken via hydrolysis.

Edit (for the 3rd time no less) I see the ambiguity in my post could have been avoided if I'd stated that unfolding breaks the hydrogen bonds, and not the peptide bonds.

[ManOfSteel2003]

Originally posted by MushMouth
He was talking about digestion, and why it was different from denaturing food by heat. When he said that denaturing breaks the bonds, I thought he meant the peptide bonds, and hence my answer that the bonds had to be broken via hydrolysis.

Good call bro.

[w00t w00t]

Where's str8flexed when you need him.

[ManOfSteel2003]

Originally posted by w00t w00t
Where's str8flexed when you need him.

I think we covered it pretty well, what are you talking about? Layne is a biochemistry major, I'm sure he could clear up any further questions you have.

[rapidgrowth]

Alright, maybe you guys covered it, but i still don't see the light. Why is it recommended to take non-denatured protein? This is my question. Does your body not absorb protein as well if it is denatured? If you can answer it in laymans terms that would be great. I read the post about the cooked egg and how not all denaturing is bad... so is the topic of denaturing irrelevant? Can you denature protein before consuming and have no loss vs consuming non-denatured protein?

[ManOfSteel2003]

Yes, the topic of denaturation of proteins is irrelevant. Unless the proteins were damaged by excessive cooking to the point where the actual chemical structure was broken down, the body has certain proteins that can reorganize and refold the denatured proteins into their correct chemical sequence. Nothing to worry about whatsoever.

[rapidgrowth]

Awesome, thank you for clearing this up ManOfSteel2003. I'm going to call attention to this post when next time I hear someone caution against denatured protein.

P.S. is there a term for when the chemical structure of protein is damaged or broken down by, i.e. excess heat?

[CerealKiller]

This link may be helpful to you.


http://newton.dep.anl.gov/askasci/mole00/mole00018.htm

[ManOfSteel2003]

Originally posted by CerealKiller
This link may be helpful to you.


http://newton.dep.anl.gov/askasci/mole00/mole00018.htm

Yep, that's what I was talking about.

[ManOfSteel2003]

Originally posted by rapidgrowth
Awesome, thank you for clearing this up ManOfSteel2003. I'm going to call attention to this post when next time I hear someone caution against denatured protein.

P.S. is there a term for when the chemical structure of protein is damaged or broken down by, i.e. excess heat?

No problem bro. No need to get overly technical, lets just call the structural decomposition of the proteins in cooked food "burned" lol.

[bunny24]

PM me manofsteel2003

[John.K]

Enyzmes are specific with regard to substrates. Protein conformation is thus important because the active sites for enzymes are specific. If the protein is in a conformation that is "not recognized," it could be shunted into another pathway. Who knows. There are so many pathways, and cerevisiae is obviously different from human.

This lock and key hypothesis is not iron clad, though.

[John.K]

PS - What I mean is that denaturing changes a protein's conformation. This could impact its ability to act as the key in the lock, as described in the E+S discussion above. So theoretically, this denaturation could impact its utlimate fate as it cycles through the body's biochemistry. This is one reason why non-denatured protein could be important.

Note that many proteins "spontaneously" refold (i.e., it is thermodynamically favorable for them to resume its original shape). There is also a class of enzymes that I am aware of that participate in protein folding. And the active sites of enzymes are not quite fixed. Because I have no real expertise in human physiology, I can't really say with certainty that non-denatured protein will not be catabolized via Urea Cycle, etc.

The biochemistry can be, to a degree, redundant. We are already aware of the chemistry involved. What makes it so thrilling is the spectacular number of pathways that no doubt meet in the interstices created by certain common enzymes. But all this is only a long way of saying what I should have said at the outset: I'm just guessing.

[ManOfSteel2003]

The human body is a spectacular thing, there is no reason to only consume "undenatured" protein sources. If someone is advertising that, then it's just a scheme to fool people into buying their product. No need to look too much into this topic. Just don't overcook your food.

[Victornado]

The human body is a spectacular thing, there is no reason to only consume "undenatured" protein sources. If someone is advertising that, then it's just a scheme to fool people into buying their product. No need to look too much into this topic. Just don't overcook your food.

The only problem is that you can't control the "over cooking" of the high heat processed protein powders that you buy which is why undenatured or non-denatured is recommended. Most likely a product that is not specifically labeled as undenatured or non-denatured is by default "over cooked" in the processing of the product by extended high heat processing as well as harsh chemical treatment during the extraction process. It is a much cheaper process and you can pretty much bet that most companies take the cheap route to increase profits.

[WillBrink]

So what I am getting from this is before you absorb any benefits from the protein it becomes denatured. Therefore leading me to ask... what is the importance of buying non-denatured protein if your stomach is going to denature it before you absorb it anyway?

It's not about undenatured protein, it's about undernatured whey. Studies found undernatured whey had positive impact on immunity, GSH levels, etc. The reasons are briefly covered below (1). Two, the digestion and absorption of some proteins are actually improved by being exposed to heat and denatured. There's no universal denatured proteins are "good" or "bad" contrary to what some may have you believe.

Technical issue: digestion does not break down protein into aminos, but into aminos and short peptides. Some of those peptides can have biological activity.

(1) http://www.brinkzone.com/articles/whey-qa/