Cobalt Essay Exam

What are rich dietary sources of cobalt?

Animal products such as meat, fish, eggs, and dairy; also found in fortified cereals. Animals like ruminants acquire cobalt through ruminal microbiota that can produce Vitamin B12.

What is the average concentration of cobalt in the Earth's crust?

Comprises around 0.003% of the Earth's crust, with an average content of 25-30 ppm.

What is the total amount of cobalt in a 70 kg human body?

Approximately 0.0011 grams.

What is the recommended daily amount of vitamin B12 for adults?

At least 2.4 micrograms.

How is cobalt assimilated and transported in the body?

Bound to proteins in VITAMIN B12 in food, released by saliva, then binds to haptocorrin, and later combines with intrinsic factor for absorption in the distal ileum. Then enters bloodstream and can participate in metabolism.

What is the biological function of cobalt in the body?

Essential for vitamin B12, critical coenzyme for cell mitosis, red blood cell formation, creating neurotransmitters, nerve function, amino acid formation, and DNA production.

Is cobalt toxic at high levels?

Organic cobalt has low toxicity, but inorganic salts containing cobalt (Cobaltous chloride, CoCl2, or cobaltous sulfate, CoSO4) are considered more toxic at high levels via the respiratory route.

How is Cobalt toxic to the body?

Mismetallation in enzymes, which inactivates them. affects multiple organ systems (endocrine, cardiovascular, nervous system, etc), can inhibit enzymes responsible for protein and RNA synthesis. Can also inhibit red blood cell production due to binding to transferrin resulting in impaired oxygen transport

How is cobalt bound in vitamin B12?

coordination complex of cobalt; Cobalt is inserted into the core (corrin ring) of the vitamin B12 molecule by a metal inserting enzyme to form metal-carbon bonds.

what are the components to vitamin B12?

the corrin ring that houses the cobalt, dimethyldenzimidazole (nucleotide loop) attached to the corrin ring, and an upper ligand (can swap for adenosyl ligand, cyanide, hydroxide, or methyl)

why is cobalt important to vitamin B12?

cobalt can form metal carbon bonds, which is facilitated by the powerful nucleophilicity of the Co(I) species. Helps rearrange carbon chains

What are the symptoms of cobalt deficiency?

Anemia, fatigue, muscle weakness, intestinal problems, nerve damage, mood disturbances, and poor appetite.

What health risks are associated with cobalt deficiency?

May cause developmental abnormalities during pregnancy, hypofunction of the thyroid, and increase the risk of anemia. Vegans and vegetarians more susceptible.

What coenzymes does cobalt act as a cofactor for and what are their functions?

Methylmalonyl-CoA mutase and methionine synthase; support amino acid synthesis, as well as fatty acid and amino acid breakdown. Vitamin B12 deficiency decreases activity of both enzymes, and can result in anemia

what are the 3 binding proteins needed in Vitamin B12 intake?

haptocorrin, intrinsic factor, and transcobalamin

what form does cobalt primarily take when used as a cofactor?

cobalt corrinoids, where its cobalt-carbon bond properties are used to catalyze chemically challenging biotransformations

when used by itself, what is cobalt a cofactor for?

Nitrogen fixation bacteria need it to fix atmospheric nitrogen into ammonia.

Importance of Cobalt-Carbon bonds

weaker than other metal-carbon bonds, susceptible to homolytic cleavage. Used by enzymes to generate a highly reactive adenosyl radical for catalysis by cleaving the bond

what are the four forms of vitamin B12? (coenzyme)

Adenosylcobalamin, cyanocobalamin, hydroxocobalamin, and methylcobalamin

what is the function of adenosylcobalamin?

cofactor for carbon skeleton rearrangements. helps form the deoxyadenosyl radical through homolytic cleavage of the carbon-cobalt bond. Used as a coenzyme by methylmalonyl-CoA mutase.

what is the function of cyanocobalamin?

manufactured version of b12, used to treat b12 deficiency or cyanide poisoning. After consumption, the cyanide ligand is replaced by other groups (adenosyl, methyl) to make the biologically active forms. Believed to function as storage/transport forms of the molecule.

what is the function of hydroxocobalamin?

B12 supplement, used to treat deficiency. Has a hydroxide group for its ligand. Converted either to methylcobalamin or adenosylcobalamin. Believed to function as storage/transport forms of the molecule.

what is the function of Methylcobalamin?

Contains metal-alkyl bonds. One of two active coenzymes used by B12 dependent enzymes, the specific form used by methionine synthase. Responsible for the biomethylation of certain heavy metals in the environment

what oxidation state is cobalt in when used biologically?

+3

how is Vitamin B12 synthesized?

Can only be made by bacteria and Archea. synthesis route and stage at which the cobalt is added is dependent on the organism (anaerobic vs aerobic) as well as the need for oxygen.

corrin ring coordination complex formed with cobalt (cobyrinic acid) → amide formation (cobryric acid) → cobalt ligated by adenosyl group → aminopropanol sidechain added → assembly of nucleotide group

methionine synthase

vitamin B12 dependent, required for synthesis of the amino acid methionine from homocysteine, and the methylation of sites in DNA, RNA, and proteins

methylmalonyl-CoA mutase

vitamin B12 dependent, required in metabolism for the degradation of fatty acids and amino acids.