Sulfur & Mercury

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Sulfur & Mercury

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Mercury, in its various forms, has a great affinity for certain minerals, as

well as protein and non-protein molecules in the body. Mercurials have a

great attraction to the sulfhydryls or thiols. The mercury atom or molecule

will

tend to bind with any molecule present that has sulfur or a sulfur-hydrogen

combination in its structure. This process of combining with a metal to form

a complex in which the metallic ion is sequestered and firmly bound is called

chelation. A thiol is any organic compound containing a univalent radical

called a sulfhydryl and identified by the symbol -SH (sulfur-hydrogen). A thiol

can attract one atom of mercury in the ionized form and have it combine with

itself. Because it is a radical, it can enter into or leave this combination

without any change. Mercury and lead both have a great affinity for sulfur

and sulfhydryls and are capable of affecting the transsulfuration pathways in

the body.

 

The primary sulfur-containing protein amino acids in the body are cystine,

cysteine, methionine, and taurine. There is also a sulfur-containing

tripeptide (having three amino acids) called glutathione that is composed of

glutamic

acid, cysteine, and glycine. Sulfur exists in a reduced form (-SH) in

cysteine and in an oxidized form (-S-S) as the double molecule cystine.

Whenever

mercury binds to one of these sulfur-containing molecules, it reduces the

molecule's availability for normal metabolic functions.

 

 

Sulfur is present in all proteins, which makes it universally available

throughout the body for binding with mercury. Some of the important biochemical

sulfur-containing compounds of the body besides glutathione are insulin,

prolactin, growth hormone, and vasopressin, and science has not yet

investigated

the effect of mercury upon them. Mercury has a particularly high affinity for

thiol groups and progressively less for other groups in the following

sequence: sulfur, amides, amines, carbon, and phosphate. Because of this,

mercury

has the potential of binding to proteins throughout the body. Mercury compounds

are formed by the binding of mercury to the biological binders albumin or

cysteine.

 

 

The principal biological reaction of mercury is with thiols to form mercury

mercaptides. The sulfur groups are often referred to as mercaptans because

of their marked affinity for mercury. Mercaptan is defined as any compound

containing reduced sulfur bound to carbon. When a metal, such as mercury,

replaces the hydrogen ion of the reduced sulfur, the resulting compound is

called a

mercaptide. Mercury can form at least three compounds with cysteine in which

all or a part of the mercury is bound firmly as a mercaptide. Mercury may

cause damage, especially to the placenta, by inactivation of sulfhydryl groups

in cellular enzymes. Mercury interacts with sulfhydryl groups and disulfide

bonds, as a result of which specific membrane transport is blocked and

selective permeability of the membrane is altered. Mercury also combines readily

with phosphate and heterocyclic base groups of DNA. It also combines with other

ligands: amide, amine, carboxyl and phosphoryl groups.

 

Homocysteine

Homocysteine is a natural substance made by the body. Homocysteine functions

at a metabolic crossroad that can affect all the methyl and sulfur group

metabolism of key enzymes, hormones, and vital nutrients. Many people lack the

ability to break it down completely, and high homocysteine levels usually

occur due to the inability to clear homocysteine because of faulty methionine

pathways (mercury and lead toxicity). The result is a buildup of homocysteine in

the system. When it is not completely broken down, homocysteine becomes a

very dangerous substance that can exert harmful effects and increase

disease-causing oxidation. When it is broken down completely, it can furnish

necessary

substances for other beneficial reactions in the body (methyl and sulfur

groups). These necessary substances provide the fuel for vital processes like

liver detoxification, adrenal gland support, neurotransmitter synthesis, and

joint cartilage and bone regeneration. Homocysteine is a very dangerous

substance that is harmful to the arteries, which makes it a risk factor for

heart

disease if it is not broken down completely.

 

 

 

Homocysteine can cause clotting, increase harmful oxidation, and can injure

the blood vessel wall (especially if already weakened by x-rays), allowing

cholesterol and fat to infiltrate into the wall and cause what is known as a

foam cell. This foam cell swells and protrudes into the space of the artery and

obstructs the blood flow, potentially resulting in a heart attack. The

artery is usually damaged and cholesterol is oxidized before infiltration into

an

artery and creation of a foam cell can occur, and homocysteine can damage the

artery, oxidize the cholesterol, and decrease circulation, all of which

increase the risk of heart disease.

 

 

The first correlation between homocysteine and disease involved

cardiovascular disease, but since then, toxic effects have been revealed on

other organ

systems, including the liver, adrenals, joints, nerves, and general system

blood vessels (inclusive of placental tearing). Neuropsychiatric conditions

have

also been traced to homocysteine problems, and a correctly functioning

pathway is vital to neurotransmitter synthesis. Other conditions which have

been

linked to high homocysteine levels include neural tube defects, multiple

sclerosis, rheumatoid arthritis, spontaneous abortion, placental abruption,

renal

failure, osteoporosis, and type II diabetes.

 

 

Homocysteine is not toxic when the pathway is functioning properly.

Synergistic nutrients facilitate the homocysteine pathway, preventing toxic

levels of

homocysteine from accumulating, and make it possible for a functioning

pathway to provide necessary methyl groups and sulfur groups for a myriad of

biochemical reactions, especially those needed for detoxification and joint and

cartilage repair. Nutrients which facilitate the methionine pathway and reduce

homocysteine include betaine, dimethylglycine, and vitamins B6, B12, folic

acid, niacinamide, choline, betaine, dimethylglycine, magnesium, and

molybdenum. Homocysteine is recycled to methionine in the presence of B12,

folic

acid, and methyl donors such as choline or betaine (trimethylglycine). B6

(pyridoxyl-5-phosphate is the active form) and magnesium help convert

homocysteine

to cysteine. Molybdenum is an essential trace mineral necessary to convert the

toxic sulfite molecule to the important sulfate molecule needed for many

biochemical reactions.

Niacinamide, a B vitamin, can increase the activity of two crucial enzymes

needed to facilitate conversion of homocysteine to non-toxic substances.

Niacinamide is also necessary for steroid hormone synthesis (cortisol,

estrogen,

progesterone, testosterone, DHEA), and when chronic stress on the adrenals

favors cortisol production, a limitation in niacinamide and/or precursors

allows

cortisol to be made at the expense of other steroid hormones (such as DHEA).

This results in increasingly large ratios of cortisol to DHEA, leading to

tissue insensitivity to insulin. All the excess cortisol will need to be

conjugated (detoxed in the liver), and this happens largely through

sulfur-dependent detoxification pathways in the liver. For this, the

homocysteine path has

to be functioning to provide the sulfur groups for liver detoxification.

Providing these sulfur groups can take some of the stress off the adrenals when

cortisol is excessive. Zinc, selenium and magnesium are all minerals which are

important co-factors in enzyme reactions of the homocysteine pathway. Zinc

and selenium are co-factors for antioxidant enzymes. Magnesium is needed to

convert methionine to SAM (S-adenosylmethionine) for the end reaction which

converts the toxic sulfite to the essential sulfate, and for glucose metabolism

(glucose is a substrate for glucuronic acid, hyaluronic acid,

N-acetyl-glucosamine, and chondroitin sulfate--all building blocks for

cartilage and joint

repair). Chronic mercury inhalation from mercury fillings, with its great

affinity to bind to methionine and cysteine can decrease the availability of

these amino acids and affect the metabolism of both vitamin B12 and folic

acid.

 

 

 

Mercury can inhibit or modify how the body uses ATP, zinc, selenium,

rubidium, vitamins A and C, and calcium. Cancer cells have altered sodium and

calcium transport and reduced oxygen transport through the cell membrane. The

oxygen deficiency within the cell reduces or eliminates the ability of the cell

to

oxidize glucose to carbon dioxide, which in turn, results in the conversion

of glucose to lactic acid, lowering cellular pH into the acid range. These

combined effects radically change cell metabolism and ultimately DNA

replication. Mercury can alter sodium and calcium transport and also reduce the

amount

of oxygen transported. Mercury competes with calcium for cellular binding

sites and, through this mechanism, can decrease cellular calcium or increase

extracellular calcium. Mercury binds avidly to rubidium and selenium. Decreases

in available selenium can also reduce available GSH-Px (glutathione

peroxidase), which, in turn, causes a proliferation of free radical cellular

damage.

Mercury, at extremely low levels, can inhibit the respiratory burst of

killer-cell leukocytes, reducing their effectiveness in controlling cancer cell

proliferation.

Cysteine and Cystine

Cysteine (sis-tee-in) is a unique amino acid, largely by virtue of its

sulfhydryl group. It is an important constituent of proteins, being largely

responsible for their molecular configuration, either by forming disulfide

bonds

with other cysteine molecules incorporated into the same protein or by forming

disulfide bonds with free cysteine. It can link together a number of separate

proteins or polypeptides by forming disulfide bonds between cysteine

residues in different molecules. Cysteine is made from two other amino acids,

methionine and serine. Methionine furnishes the sulfur atom and serine

furnishes

the carbon skeleton in the synthesis of cysteine. Cysteine is produced by

enzymatic or acid hydrolysis of proteins. Cysteine can be oxidized to cystine

(sis-tin), which is rather insoluble in water. Sometimes it can be found in the

urine and in the bladder in a crystal form where it will form cystine

calculus (stones) in the kidneys or bladder. Cystine is the main

sulfur-containing

compound of the protein molecule. Upon reduction, cystine produces two

molecules of cysteine. Heavy metals catalyze the oxidation of cysteine to

cystine

and also react with cysteine to form mercaptides. Cysteine is very soluble in

water and therefore can be easily eliminated via the urine.

 

 

However, cysteine can be oxidized to cystine, which can then present the

potential of stone problems. If an adequate supply of vitamin C is available,

it

will help keep cysteine in its reduced and soluble form, thereby preventing

the formation of stones. The ratio of vitamin C to cysteine should be

three-to-one. Cystathionase, an enzyme that is necessary to change

cystathionine

into cysteine, and which is present in humans postnatally, is not present in

human fetal liver or brain. Cysteine is not considered an essential amino acid

in adults. Cysteine is an essential amino acid for the human fetus, and for

prematurely born and full term infants for a short period after birth. Its

concentration in maternal plasma is greater than or equal to that in fetal

plasma. Cystathionine, which is present in human brain in large concentrations,

may

not be needed until some time after birth.

Methionine

Methionine is one of the essential amino acids required in the diet, whereas

cysteine is considered to be non-essential. Eighty to 90% of the daily

requirement can be replaced by cystine. The ability for one sulfur to replace

another is called transsulfuration and represents an important route for either

cysteine or cystine. Plasma levels of taurine, serine, methionine, and

threonine have been found to be significantly lower in patients with essential

hypertension (high blood pressure). The levels of these four amino acids, as

well

as total sulfur amino acids, correlated inversely with systolic blood

pressure. Individuals with mercury amalgam dental fillings could have low

plasma

sulfur amino acids, leading to high blood pressure. Mercury has been shown to

affect methionine use.

Taurine

Taurine is a sulfur-containing amino acid that the body makes from cysteine.

Methionine is a precursor for cysteine and taurine biosynthesis. There are

two primary bile acids needed to break down fats; one of them, taurocholic

acid, cannot be produced without taurine. Taurine is concentrated in the brain

where it functions as a neurotransmitter and/or as a modulator of

neurotransmission, preventing excess electrical activity, such as that

occurring during

epileptic episodes. Taurine plays a major role in the transport regulation of

blood electrolytes (calcium and potassium) and may affect in the

cardiovascular system. Excretion in pregnant women falls dramatically starting

at week-9

of pregnancy. Reserves of taurine are increased for use during the latter

phases of pregnancy. Concentrations are higher in the fetal liver and brain and

some believe that it plays a role in brain development and also functions as

a growth modulator. Both mercury and lead have a great affinity for the

sulfur atom. Mercury can serously interfere in the transsulfuration pathway at

many different locations, ultimately leading to a deficiency or reduction in

available taurine.

 

Glutathione

Glutathione is present in almost all cells in the body in rather high

concentrations. Glutathione serves as a storage and transport form of cysteine

and

also as a respiratory carrier of oxygen, both extremely important metabolic

functions. Within the cell itself, it has some very important metabolic

functions such as protecting the cells against damage that can be caused by

free

radicals and hydrogen peroxide. In the liver, glutathione is a reservoir of

cysteine which is utilized for protein synthesis. Glutathione can also replace

cysteine derived from methionine, thus exerting a methionine sparing action.

Vitamins C and E are two key nutrients that go through this recycling process.

Once they have performed their function as an antioxidant, scavenging free

radicals, they are reduced to an inactive state and must be regenerated to

their original form. This process requires an adequate supply of reduced

glutathione. Reduced glutathione (GSH) is present in red blood cells where it

is

functionally associated with the enzyme glucose-6-phosphate dehydrogenase

(G6PD)

and the coenzyme reduced nicotinamide-adenine dinucleotide phosphate

(NADPH). Both G6PD and NADPH are needed to maintain red blood cell integrity.

 

 

 

Glutathione also plays a part in how our immune systems function. When the

supply of glutathione is low, or has been depleted, this can inhibit the

activation of lymphocytes, and may also have a bearing on the response of

cytotoxic T-lymphocytes. The ability of mercury to affect the available supply

of

glutathione also affects these same lymphocyte functions. Mercury also

inactivates G6PD, which results in altered red blood cell membrane permeability

and

blocking of active glucose transport into cells. Mercury itself increases red

blood cell membrane permeability. The altered membrane permeability, in turn,

disrupts a large number of essential membrane functions, ultimately leading

to cell death. Glutathione peroxidase (GSH-Px) activity in the liver, kidneys,

testes, and erythrocytes is significantly depressed by silver and mercuric

chloride.

 

 

Glutathione peroxidase protects the human brain. When polyunsaturated fatty

acids, which are located primarily in the brain, are oxidized, organic

hydroperoxides are formed that can only be reduced by GSH-Px. Alterations in

GSH-Px

activity and tissue damage caused by peroxide accumulation is of

significance in the development of senility and degenerative neurological

diseases. One

of the primary ways the body gets rid of metal compounds is through a pathway

that goes from the liver into the bile where they are then transported to

the small intestine and excreted in the feces. Inorganic mercury is complexed

with glutathione in the bile, suggesting that glutathione status is a major

consideration in the biliary secretion of mercury. This same pathway is

affected by a mercury induced reduction of available taurine needed to produce

bile

acid (taurocholic acid).

 

 

When the microflora of the intestine have been reduced through stress, poor

diet, use of antibiotics and other drugs, fecal content of mercury is greatly

reduced. Instead of being excreted in the feces, the mercury gets

recirculated back to the liver. The person who is under stress, eating a poor

diet,

and/or taking antibiotics will tend to maintain a higher body burden of mercury

derived from dietary sources--especially if they are eating fish.