|
 Coenzymes are:
* Small organic molecules which are derived from vitamins,
* Required in small
amounts are regenerated physiologically, so massive doses of
supplements are not really essential, and
* Primarily thought of as water soluble or fat soluble. Mammals are
unable to synthesize their own vitamins, but the bacteria can. This
explains the human nutritional requirements for vitamins in the diet or
as supplements.
*
Bound to enzymes in a reversible manner i.e. under appropriate
conditions it is possible to dissociate them from the enzyme
* Bound to enzymes and actually take part in the chemical reactions and
are sometime called cosubstrates - when covalently bound to the enzyme. When this is the
case, the bound coenzyme is called a Prosthetic
Group.
For
additional information, visit the following links:
See Introduction
to Vitamins from University of Indiana, for a table listing the
principal vitamins active in this role.
See Role
of Coenzymes from University of Indiana.
Picure from Enzymes-
The Biological catalysts - Timothy Paustian, University of
Wisconsin-Madison
Cofactors are:
* Metal ions, part of essential micro nutrients,
* Bind reversibly to enzymes but are not generally chemically altered
during the reaction. In a few cases there may be oxidation or reduction
of such metal ions but it is not a common phenomenon. It should be
remembered that metal cofactors are also required in amounts generally
available from the diet. Supplements should be taken with caution.
It
must be remembered that not all enzymes require coenzymes for their
catalytic activity. But those that do convert a inactive form to the
active form following binding:
Apoenzyme
+ Coenzyme or Cofactor ---> Holoenzyme
inactive
active
(It must be
remembered that the terms coenzyme/cofactor are sometimes used
interchangeably in Biochemistry literature.)
Check
out the Holo-enzyme
structure of glucose oxidase from the UK (this requires Shockwave)
See also Pharmaceutical
Biochemistry I: Enzyme Cofactors by Richard A. Gibbs, Ph.D. at
Wayne State University.
Table Summarizing Coenzymes and Cofactors
|
Coenzyme or Prosthetic Group
|
Enzymic or Other Function
|
Essential Nutritional Factor or Vitamin
|
Source of Nutrient
|
Clinical Application
|
| Nicotinamide Adenine |
As hydrogen acceptor
of Nicotinic acid |
Dinucleotide
(NAD+ or DPH+) dehydrogenases (Niacin)
Dinucleotide Phosphate dehydrogenases
(NADP+
or TPH+) |
Beef, broccoli, carrots, cheese,
corn flour, eggs, fish, milk, pork,
potatoes,
tomatoes, and whole wheat.
See
Vitamins:
Introduction and Index for fat soluble and water-soluble vitamins. |
Macular
Edema Associated With Nicotinic Acid (Niacin)
JAMA
June 3, 1998 |
| Adenosine Triphosphate (ATP) |
Trans-phosphorylation |
. |
None |
Sperm,
from Sexual
Reproduction in Humans |
| Pyridoxal phosphate |
Transaminases, amino acid decarboxylases, racemases |
Pyridoxine or B6 |
Pork, glandular meats, cereal bran and germ, milk, egg
yolk, oatmeal, and legumes. Synthesized by intestinal bacteria.
SupraHealth,
Inc. |
Folate
and Vitamin B6 From Diet and Supplements in Relation to Risk of
Coronary Heart Disease Among
Women.
JAMA 2/4/98 |
| Thiamine Pyrophosphate (TPP) |
Oxidative decarboxylation |
Thiamine or Vit. B1 |
Pork, liver, organ meats,
legumes, whole grain and enriched cereals and breads, wheat germ,
potatoes. Synthesized by intestinal bacteria.
SupraHealth. |
Alcoholic
Polyneuropathy and more |
| Flavin Mononucleotide (FMN) |
As hydrogen acceptor of
dehydrogenases |
Riboflavin
See
Riboflavin
Metabolism |
Amount
of Riboflavin in foods |
RIBOFLAVIN
from nutrition.org |
| Flavin Adenine Dinucleotide (FAD) |
As hydrogen acceptor of dehydrogenases |
Riboflavin |
..also liver and yeast
from
americahealth.com |
Riboflavin
Deficiency Increases Risk of Preeclampsia |
| Coenzyme A (CoA) |
Acetyl or other acyl group
transfer, fatty acid synthesis and oxidation |
Pantothenic acid |
all natural food; rich in yeast,
liver, egg yolk, rice, wheat bran, germ, peanut, pea.
See MICRONUTRIENTS AND WATER VITAMINS
PANTOTHENIC ACID
|
Chapter
4: Pantothenate, a Vitamin that May Work (CoA and longevity!) |
| Iron protoporphyrins |
In catalase, peroxidase, cytochromes, hemoglobin |
None |
. |
Porphyrias.
Iron
Nutrition and Exercise
|
| 6,8,-Dithio-n-Octanoic acid (Lipoic acid) |
Oxidative decarboxylation as hydrogen and acyl acceptor |
microorganisms |
in foods such as meats and spinach
Alpha
Lipoic Acid |
Lipoic
Acid: A blessing for Diabetics Part II by Richard A. Passwater,
Ph.D, from Solgar |
| Tetrahydrofolic acid (THF) |
One carbon transfer |
Folic acid |
leafy dark green vegetables, citrus fruits and juices,
and lentils
from
Food
and Drug Administration |
Folic
Acid Preventing Birth Defects, and More |
| Biotin |
CO2 transfer |
Biotin
- Vitamin H
|
Brewer’s yeast, cereals and grains, peanuts, walnuts,
molasses, milk, egg yolks, lentils and peas
Cybervitamins |
Biotin
Deficiency, from eMedicine |
| Cobamide |
Group transfer (alkyl) |
Cobalamine, vitamin B12 |
Meats, fish, poultry, dairy
products,
eggs.
B
Vitamins:
The Bottom Line
|
Deficiency
Signs and Symptoms
|
|
