Importance of transition metals in physiological processes

The sheer range of roles of transition metals and the (often complex) mechanisms underlying their chemistry are far beyond the scope of this textbook. However, the following examples provide some insights into some key functional aspects of this important group of elements. 

While simple blood smears can help with diagnosis of HbS, abnormal haemoglobins resulting in other haemoglobinopathies can be investigated by comparing 

As the name suggests, cyanocobalamin (vitamin B12) is a compound of cobalt (Co(lll)). With a complex organic structure, this essential water-soluble vitamin is obtained from dietary animal sources and is required for deoxyribonucleic acid (DNA) synthesis, where enzymes that use vitamin B12 are involved in the transfer of one-carbon units. The absorption of this vitamin from the gastrointestinal tract only occurs when intrinsic factor glycoprotein is present. While the body can store up to a 12-month supply of vitamin B12, rapid growth or conditions causing rapid cell turnover can increase the body s requirement for this vitamin. 

Absorption of vitamin B12 can be investigated in several ways after oral delivery of radioactive vitamin B12 (e.g. containing Co) and subsequent measurement of radioactivity in faecal excretion, whole body counting or liver uptake, plasma radioactivity or the popular Schilling test. For the Schilling test, urinary excretion of radioactive vitamin B12 is measured 24 h following oral delivery, and impaired absorption may indicate intrinsic factor deficiency bacterial colonization of the small intestine (stagnant gut syndrome) or ileal disease. 

Vitamin B12 is a controlling factor for pernicious anaemia, but since it is difficult to design a diet lacking this vitamin, this condition is very rare. As animal food products are the richest source of vitamin B12, most people that develop deficiency of this vitamin are true vegetarians or infants of vegetarian mothers. Symptoms of Bi2 deficiency have a slow onset, as minute amounts are required and it is efficiently stored, but they include anaemia, a smooth red painful tongue (glossitis) 

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To outline and discuss the importance of transition metals in physiological processes. 

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