Storage

The total iron content in men is about 50 nig'kg: women have slightly less.

Iron is stored within polymeric ferritin complexes composed of 24 light and heavy apofcrritin monomers w ith 0.7nm wide pores. The II-chain has a region with ferrox-idasc activity buried inside the protein fold that promotes the reaction of one dioxy-gen molecule per two Fe2 ions resulting in the production of hydrogen peroxide. Genetically distinct ferritin isoforms are expressed in liver and hematopoietic tissues.

Typically, about 2000 iron atoms (as FeOOH- ferric iron oxyhydroxide) reside in one ferritin polymer, much less than the maximum of about 4300. When the capacity of ferritin is exceeded iron associates with the poorly soluble hemosiderin. Ferritin incorporates and releases iron rapidly, hemosiderin does so much more slowly. Reducing substances such as ascorbate, FMNH2, and possibly sulfide facilitate the rapid release of iron from ferritin (Cassanelli and Moulis, 2001). The pores of the ferritin envelope are wide enough for glucose and other small organic molecules to diffuse into the iron-containing interior.

sCHj

3 lerrocyto-chrome

3 lerrocyto-chrome

3 NAD(P)M NADPH -lemflerno-

3 NAD(P)M NADPH -lemflerno-

\( CO • Fe? (FMN • FAD) ¿s CH3 3 ferrtcytoehroma + 3 HfO

oxygenaseN^

COOH

Heme

\( CO • Fe? (FMN • FAD) ¿s CH3 3 ferrtcytoehroma + 3 HfO

COOH

Heme

COOH

Bilirubin IX»

Figure 11,8 Heme is broken down in microsomes of spleen and other organs

COOH

Bilirubin IX»

Figure 11,8 Heme is broken down in microsomes of spleen and other organs

Autism

Autism

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