Vitamin B12 - Structure, Forms, Metabolism, Functions and Deficiency || Vitamin B12 Biochemistry

Vitamin B12 - Structure, Forms, Metabolism, Functions and Deficiency - This is the video on one of the important water soluble vitamin i.e Vitamin B12 with examples of theory questions and NEET PG MCQs.
00:00 - Introduction
00:47 - Examples of theory questions
01:21 - Synonyms of Vitamin B12
01:37 - Vitamin B12 Structure
02:58 - Forms of Vitamin B12
03:48 - Dietary Sources of Vitamin B12
04:28 - RDA of Vitamin B12
04:50 - Absorption , Transport and Storage of Vitamin B12 (Metabolism of Vitamin B12)
07:55 - Functions of Vitamin B12
08:21 - Conversion of methylmalonyl CoA to succinyl CoA
09:18 - Role of Vitamin B12 conversion of homocysteine to methionine (Folate Trap)
10:23 - Causes of Vitamin B12 Deficiency
12:09 - Deficiency Manifestations of Vitamin B12
12:53 - Subacute combined regeneration
15:36 - Assessment of Vitamin B12 Deficiency
15:52 - Schiilling Test
17:17 - NEET PG Biochemistry MCQs

Cobalamin (Vitamin B12)

Other names – extrinsic factor of castle and antipernicious anemia factor
It is water soluble, heat stable and red in color
It contains 4.35% cobalt by weight

Structure
Vitamin B12 bears a complex corrin ring (containing pyrrols similar to porphyrin), linked to a cobalt atom held in the center of the corrin ring, by four coordination bonds with the nitrogen of the pyrrole groups.

Sources
Dietary sources of vitamin B12 are of animal origin ; meat, eggs, milk, dairy products, fish, poultry, etc.
Liver is the richest source. Curd is a good source, because lactobacillus can synthesize B12.
Vitamin B12 is absent in plant foods.
Humans obtain small amounts of B12 from intestinal flora.

Nutritional Requirements (RDA )

Normal daily requirement is 1–2 μg/day.
During pregnancy and lactation, this is increased to 2 μg/day.
Those who take folic acid, should also take vitamin B12. Elderly people are advised to take vitamin B12 supplementation..

Functions
There are only two human enzyme systems that are known to require vitamin B12 coenzyme.
1. Isomerization of methylmalonyl-CoA to succinyl-CoA
2. Conversion of homocysteine to methionine


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