10

votes

Does Gelatin Intake Reduce Ascorbic Acid Requirements?

Answered on August 19, 2014
Created May 25, 2012 at 4:37 AM

Ascorbic acid's primary role is as a cofactor in the hydroxylation reaction of proline and lysine for the production of collagen.

"Proline hydroxylation requires ascorbic acid (vitamin C). The most obvious, first effects (gingival and hair problems) of absence of ascorbic acid in humans come from the resulting defect in hydroxylation of proline residues of collagen, with reduced stability of the collagen molecule, causing scurvy."

http://en.wikipedia.org/wiki/Hydroxyproline#Clinical_significance

Can we directly utilize the hydroxyproline and hydroxylysine in gelatine to produce collagen thereby conserving bodily stores of ascorbic acid?

C1484e8cfca0cc00f40da25d36f689b8

(374)

on May 29, 2012
at 06:49 AM

Our bodies typically code for 20 amino acids. Selenocysteine is the very important 21st amino acid, but it requires, an activator to start the synthesis at the ribosome, an entire enzyme to make the selenocysteine, and more signals to finally bring it back and incorporate it into the protein. This is an extensive amount of work and for whatever reason we stopped at 21. Tweaking that basic framework is how we work around the limitation. Why can't be answered. Check out work of Peter Schultz to see some outrageous examples of expanding the genetic code to include more amino acids

5292a9d9f67ad0b00e6c49ae4dcdaedc

(70)

on May 26, 2012
at 12:23 PM

Adequate selenium promotes recycling of ascorbic acid: http://perfecthealthdiet.com/2010/11/danger-of-zero-carb-diets-iii-scurvy/

5292a9d9f67ad0b00e6c49ae4dcdaedc

(70)

on May 26, 2012
at 12:19 PM

http://perfecthealthdiet.com/2010/11/danger-of-zero-carb-diets-iii-scurvy/

5292a9d9f67ad0b00e6c49ae4dcdaedc

(70)

on May 26, 2012
at 02:29 AM

Hi Matt, I still think gelatin is important to supply lots of the raw material for hydroxylation. As a result of this question I'm going to start supplementing with ascorbic acid.

32f5749fa6cf7adbeb0b0b031ba82b46

(41777)

on May 26, 2012
at 12:56 AM

Very interesting question! And an answer that seems to weaken the argument for supplementing with gelatin.

5292a9d9f67ad0b00e6c49ae4dcdaedc

(70)

on May 25, 2012
at 10:30 PM

Using "primary role" in my question was a bit misleading. I meant that hydroxylation is the largest consumer of ascorbic acid, not that it was the most important use for it.

5292a9d9f67ad0b00e6c49ae4dcdaedc

(70)

on May 25, 2012
at 10:13 PM

Thanks for the comment! It would seem inefficient not to be able to recycle hydroxyproline and hydroxylysine from existing collagen. Why wouldn't this be coded for in the RNA?

5292a9d9f67ad0b00e6c49ae4dcdaedc

(70)

on May 25, 2012
at 09:33 PM

Thanks Tyler. I think it's a really important question.

276a5e631b62f8e0793987c0496364bb

(1644)

on May 25, 2012
at 02:47 PM

Someone ping a nutritionist. This is a good question.

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4 Answers

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4
C1484e8cfca0cc00f40da25d36f689b8

(374)

on May 25, 2012
at 05:14 PM

From a quick look through your wikipedia link, I don't think so. The addition of the hydroxyl group to the proline is a post translational modification done by prolyl hydroxylase. This step occurs after the protein synthesis. The vitamin c is used as a reducing agent for the Iron in the reaction (gives it electrons). The ingested hydroxy amino acids would most likely not be able to get introduced into the protein during its synthesis as they wouldn't be coded for in the RNA.

5292a9d9f67ad0b00e6c49ae4dcdaedc

(70)

on May 25, 2012
at 10:13 PM

Thanks for the comment! It would seem inefficient not to be able to recycle hydroxyproline and hydroxylysine from existing collagen. Why wouldn't this be coded for in the RNA?

C1484e8cfca0cc00f40da25d36f689b8

(374)

on May 29, 2012
at 06:49 AM

Our bodies typically code for 20 amino acids. Selenocysteine is the very important 21st amino acid, but it requires, an activator to start the synthesis at the ribosome, an entire enzyme to make the selenocysteine, and more signals to finally bring it back and incorporate it into the protein. This is an extensive amount of work and for whatever reason we stopped at 21. Tweaking that basic framework is how we work around the limitation. Why can't be answered. Check out work of Peter Schultz to see some outrageous examples of expanding the genetic code to include more amino acids

3
Fd70d71f4f8195c3a098eda4fc817d4f

(8014)

on May 25, 2012
at 05:33 PM

And let's not forget that collagen formation is not the only role of vitamin C. It's a biggie, yes, but not the only one.

5292a9d9f67ad0b00e6c49ae4dcdaedc

(70)

on May 25, 2012
at 10:30 PM

Using "primary role" in my question was a bit misleading. I meant that hydroxylation is the largest consumer of ascorbic acid, not that it was the most important use for it.

2
5292a9d9f67ad0b00e6c49ae4dcdaedc

on May 26, 2012
at 12:11 AM

Seems that the answer is no.

"Although 4-hydroxyproline, the proline congener abundant in mammalian species, is structurally similar to proline, its metabolism is distinctly different (2). A critical contributor to the physical structure of organisms, hydrox-yproline is not found in species before the evo-lution of metazoans. Preformed hydroxypro-line is not incorporated into protein presumably because all the triplet codons were occupied (2, 52). Instead, it is formed by the posttransla-tional hydroxylation of proline in proteins (2). Since hydroxyproline is not recycled for pro-tein synthesis, its degradation continues down to 2- and 3-carbon compounds. The degrada-tive pathway, however, shares some of the en-zymes metabolizing proline (103). The ini-tial step is catalyzed by hydroxyproline oxidase (PRODH2), an enzyme encoded by a gene dis-tinct from that for proline oxidase ( PRODH) and with little overlap in substrate utilization (91). In contrast, in the second step of their degradation, hydroxyproline and proline share the same enzyme, i.e., P5C dehydrogenase (103). It is interesting that P5C reductase from animals not only converts P5C back to proline for protein synthesis, but also can reduce OH-P5C to hydroxyproline even though product hydroxyproline is not reused for protein synthe-sis (3). P5C reductase in prokaryotes, however, does not have this activity for OH-P5C (3)."

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6c2c87897b8307ce214f912bdb63d1b1

on May 29, 2012
at 05:53 AM

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