How many oxidation states does manganese has?
11 oxidation shapes
Dietary absorption of manganese
women absorb more than men
absorption decreases when intakes are excessive
What enhances the absorption of manganese?
histidine and citrate
What inhibits the absorption of manganese?
fiber, phytate and oxalate
How is manganese transported and stored?
circulates free (Mn2+) or bound to a-2 macroglobulin
liver clears all of the newly absorbes Mn
It is released bound to transferrin (requires oxidation to Mn3+ by ceruloplasmin
Manganese is cleared rapidly from the blood by all tissues and accumulated in the mitochondria
What are the functions of manganese?
-Enzyme activation and a constituent of metalloenzymes
- Macronutrient metabolism
- Pancreatic function and development
- Reproduction: prevention of sterility
- Energy metabolism: thyroid hormone synthesis
- Normal skeletal growth and development
- Anti-oxidant (Mn-SOD)
- Neurotransmitter synthesis and metabolism
How does manganese function in macronutrient metabolism?
- essential for glucose utilization
- important for protein and nucleic acid metabolism
- lipid synthesis and metabolism; cholesterol metabolism
What enzymes require manganese?
- transferases
- hydrolases
- oxio-reductasess
- ligases/synthetases
Manganese in transferase mechanism
needed as a cofactor
Xylosyl transferase and glycosyl transferase
- catalyzes the transfer of a sugar moiety (galactose) from uridine diphosphate (UDP) to an acceptor molecule
- –necessary in proteogylcans which are important components of bone and connective tissue
- –post translational protein modifications: sugars attached to ser tyr, thr or ans
Manganese in hydrolase mechanism
prolidase - (catalyzes final step in collagen degredation)
arginase - (elimination of ammonia)
Phosphoenolpyruvate carboxykinase (PEPCK) - converts oxaloacetate to phosphoenolpruvate + CO2 –essential for gluconeogenesis
Manganese in oxio-reductase mechanism
superoxide dismutase in mitochondria; prevents lipid peroxidation by superoxide radicals
Manganese in ligases / synthetases mechanism
pyruvate carboxylase - converts pyruvate to oxaloacetate
What other nutrient does manganese interact with?
Manganese and iron
high dietary non-heme Fe can reduce both Mn absorption and status in humans and vice versa
What are the symptoms of manganese deficiency?
nausea, vomiting, diarrhea
increased serum Ca, P and alkaline phosphatase
decreased growth of hair and nails
abnormal glucose tolerance
*assessed in whole blood and hair
induced in animal models;
- reduced growth, short crooked leg bones
- increased susceptibility to convulsions
- delayed sexual maturity
- females delivered still born or weak young that suffered from ataxia due to inner ear problems
How is Mn excreted?
It is excreted in the bile and feces, unlike Fe
What are they symptoms of manganese toxicity?
affects the central nervous system
insomnia, depression, delusions, apathy
anorexia, headaches
asthenia (lower extremity weakness), parkinsons like symptoms
- occurred in Mn miners
- toxicity from dietary intake has not been described
Manganese in soy formula
contains ~80 times more than breast milk - liver excretion is not mature
What groups are at risk for Mn toxicity?
welders, railroad & steel workers and miners
also present in some pesticides
- higher in the hair of violent felons
- children with learning and attention deficit disorders
What forms are found in human tissues?
Mn2+, Mn3+ and possibly Mn4+
