Elementary plant Biochemistry and Biotechnology (2+1)

Water-soluble vitamins

• The water-soluble vitamins include B-complex group and vitamin C. The important dietary sources and deficient symptoms associated with them are presented in table
 

Coenzymes
Mechanism of coenzyme action

• Coenzyme accelerates the enzymatic reaction by helping the formation of the product (s) by action as acceptor for one of the products.
  
• The substrate combines with the apoenzyme to form activated complex.
  
• But this combination takes place in the presence of coenzyme.
  
• The bond in the substrate is strained and ruptured when one of the cleavage products is directly transferred to the coenzyme, which has suitable receptor site in its structure.
  
• The other cleavage product now dissociates from the apoenzyme liberating the enzyme protein for fresh reaction.
  
• The cleavage product attached to the coenzyme is next released from the surface of the coenzyme after the completion of enzyme action.
  
• Now both apoenzyme and coenzyme are regenerated to their original form and are ready for fresh reaction.
• A prosthetic group also acts in a similar fashion with the difference that the prosthetic group is firmly attached to the surface of the apoenzyme.
Water-soluble vitamins

Vitamin	Some common dietary sources	Deficiency symptoms in humans
1.Thiamine (Vitamin B1)	Liver, meat, milk, vegetables, whole grains, nuts	Dry and wet beri-beri. Weight loss, muscle wasting, sensory changes, mental confusion, enlargement of heart, constipation
2.Riboflavin (Vitamin B2)	Liver, wheat germ, eggs, milk, green leafy vegetables, meat	Magenta-coloured tongue, fissuring at the corners of mouth and lips, dermatitis
3.Niacin (nicotininc acid)	Meat, liver, cereals, legumes	Pellagra, Dermatitis when exposed to sunlight, weakness, insomnia, impaired digestion, diarrhea, dementia, irritability, memory loss, headaches
4.Pyridoxine (vitamin B­6 or pyridoxol)	Egg yolk, fish, meat, lentils, nuts, fruits, vegetables	Convulsions, dermatitis, weight loss, irritability, weakness in infants
5.PAntothenic acid	Eggs, peanuts, liver, meat, milk, cereals, vegetables	Vomiting, abdominal distress, cramps fatigue, insomnia
6.Biotin	Liver, yeast, meat, peanuts, eggs, chocolate, dairy products, grains fruits, vegetables	Dermatitis, skin dryness, depression, muscle pain, nausea, anorexia (appetite loss)
7.Folic acid	Yeast, liver green vegetables, some fruits	Anemia leading to weakness, tiredness, sore tongue, diarrhea, irritability headache, heart palpitations
8.Cobalamin (vitamin B12)	Meat, shellfish fish, milk, eggs	Neurological disorders anemia leading to tiredness, sore tongue, constipation, headache, heart palpitations
9.Ascorbic acid (vitamin C)	Vegetables and citrus fruits	Sore gums, loose teeth, joint pain, edema, anaemia, fatigue, depression, impaired iron absorption, and impaired wound healing.