Final - manganese

Question 1

How many oxidation states does manganese has?

Answer 1

11 oxidation shapes

Question 2

Dietary absorption of manganese

Answer 2

women absorb more than men

absorption decreases when intakes are excessive

Question 3

What enhances the absorption of manganese?

Answer 3

histidine and citrate

Question 4

What inhibits the absorption of manganese?

Answer 4

fiber, phytate and oxalate

Question 5

How is manganese transported and stored?

Answer 5

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

Question 6

What are the functions of manganese?

Answer 6

-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

Question 7

How does manganese function in macronutrient metabolism?

Answer 7

• essential for glucose utilization
• important for protein and nucleic acid metabolism
• lipid synthesis and metabolism; cholesterol metabolism

Question 8

What enzymes require manganese?

Answer 8

• transferases
• hydrolases
• oxio-reductasess
• ligases/synthetases

Question 9

Manganese in transferase mechanism

Answer 9

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

Question 10

Manganese in hydrolase mechanism

Answer 10

prolidase - (catalyzes final step in collagen degredation)

arginase - (elimination of ammonia)

Phosphoenolpyruvate carboxykinase (PEPCK) - converts oxaloacetate to phosphoenolpruvate + CO2 –essential for gluconeogenesis

Question 11

Manganese in oxio-reductase mechanism

Answer 11

superoxide dismutase in mitochondria; prevents lipid peroxidation by superoxide radicals

Question 12

Manganese in ligases / synthetases mechanism

Answer 12

pyruvate carboxylase - converts pyruvate to oxaloacetate

Question 13

What other nutrient does manganese interact with?

Answer 13

Manganese and iron

high dietary non-heme Fe can reduce both Mn absorption and status in humans and vice versa

Question 14

What are the symptoms of manganese deficiency?

Answer 14

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

Question 15

How is Mn excreted?

Answer 15

It is excreted in the bile and feces, unlike Fe

Question 16

What are they symptoms of manganese toxicity?

Answer 16

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

Question 17

Manganese in soy formula

Answer 17

contains ~80 times more than breast milk - liver excretion is not mature

Question 18

What groups are at risk for Mn toxicity?

Answer 18

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

Question 19

What forms are found in human tissues?

Answer 19

Mn2+, Mn3+ and possibly Mn4+