Vitamins, Cofactors and Coenzymes - Chemistry LibreTexts
One class of these cofactors, termed coenzymes, consists of small organic molecules, Vitamins themselves are organic molecules that are needed in small. The relationship between these two terms is as follows Table 1 lists vitamins, the coenzymes derived from them, the type of reactions in which they participate, . Coenzymes are relatively small molecules compared to the protein part of the enzyme and many of the coenzymes are derived from vitamins.
Primates are unable to synthesize ascorbic acid and hence must acquire it from their diets.
The importance of ascorbate becomes strikingly evident in scurvy. Jacques Cartier in gave a vivid description of this dietary deficiency disease, which afflicted his men as they were exploring the Saint Lawrence River: Some did lose all their strength, and could not stand on their feet.
Their mouths became stinking, their gums so rotten, that all the flesh did fall off, even to the roots of the teeth, which did also almost all fall out. Lind described a controlled study establishing that scurvy could be prevented by including citrus fruits in the diet.
Anson left England in with a fleet of six ships and more than men and returned with an enormous amount of treasure, but of his crew only survived to reach home. The remainder had died of scurvy.
Why does impaired hydroxylation have such devastating consequences?
What is the relationship between vitamins and coenzymes to enzymes?
Collagen synthesized in the absence of ascorbate is less stable than the normal protein. Studies of the thermal stability of synthetic polypeptides have been especially informative. And by "carrier," I mean that co-enzymes hold on to certain things for an enzyme to make the catalysis run a little more smoothly. And a great example of a co-enzyme is NADH, which acts as an electron carrier.
Now if you remember the lactic acid fermentation reaction, where pyruvate is converted to lactic acid, you'd see that the enzyme catalyzing this reaction, lactate dehydrogenase, uses NADH as a co-enzyme in order to transfer electrons to the pyruvate molecule, in order to turn it into lactic acid. And in this sense, NADH is acting as an electron-carrying co-enzyme.
Vitamins Are Often Precursors to Coenzymes - Biochemistry - NCBI Bookshelf
And you'd see CoA appear quite often in metabolic reactions, where it will carry these two carbon acetyl groups from one molecule to another. Now, co-factors are a little different from co-enzymes.
While co-enzymes are only really involved in transferring different things from one molecule to another, co-factors are directly involved in the enzyme's catalytic mechanism. They don't strictly carry something like a co-enzyme would, but might be stabilizing the enzyme or the substrates or helping the reaction convert substrates from one form to another.
A great example of this is with the enzyme DNA polymerase. Now, you may remember that DNA is a very negatively charged molecule because of all the negatively charged phosphate groups that you'll find around it. Well, DNA polymerase uses a magnesium ion as a co-factor, which can use its big positive charge to stabilize all that negative charge on DNA.
Vitamins, Cofactors and Coenzymes
And you can see how this is different from a co-enzyme. Becomes instead of acting as a carrier molecule, the magnesium ion co-factor is stabilizing the DNA and is more directly involved in the actual catalysis.
Now, interestingly, what people normally called vitamin and minerals, like the kinds that a doctor would tell you to make sure you get enough of in your diet, are often different co-factors and co-enzymes. And what's special about vitamins and minerals is that your body can't build them up from scratch. And you need to get them from your diet in order to stay healthy.
So when we say vitamins, we typically refer to organic co-factors and co-enzymes. So two great examples are ones we just discussed. Vitamin B3, which you may see being called niacin on a food label, is actually just a precursor for NAD.
And vitamin B5 is just a precursor for co-enzyme A. Minerals, on the other hand, are inorganic, meaning they aren't carbon based.