|
 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
|
|
