NTDT401 Lecture Notes - Lecture 10: Cobalamin, Cobamamide, Methylcobalamin
6 Nov 2016
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Structure of b12: macrocyclic ring, cobalt enzyme in center: linked to 5 alanines & has a 6th linkage. 6th linkage to co can be: cn (supplement, oh (supplement, h2o, no2, 5"adenosyl, -ch3. 2 coenzyme forms: 5"adenosyl (adenosylcobalamin, -ch3 (methylcobalamin) Because b12 is the largest nutrient, what does that mean: not easily utilized, will not leave body easily --> deficiency takes a very long time. Animal products: meat, poultry, fish, shellfish, eggs, milk, milk products. Need *if* for absorption, which occurs in ileum. Causes of malabsorption: achlorydia (no hcl, no if, pancreatic insufficiency. Exists as 2 coenzyme forms (methylcobalamin & adenosylcobalamin) Functions of b12: neurological function, enzymatic reactions - methylcobalamin & adenosylcobalamin. Development and maintenance of myelin (related to sam) Myelin = on nerve surfaces --> lack of b12 = nerve damage! Reaction allows 5-methyl thf to go back to original form. Frees folate from trap! (thf can then go back to 5,10-methylene thf = nucleotide synthesis)
