Protein Metabolism::
proteins are the essential constituents of all living cells they are hydrolysed to amino acids by proteolytic enzymes and enter the portal vein to go to the liver Some amino acids are used in intact form while some amino acids are broken down and converted into urea and ammonia which are then excreted Amino acids break down and liberate energy while breaking down they exert a specific stimulating action on tissue metabolism This is Specific Dynamic Action (SDA) of proteins during the process of deamination ammonia and alpha ketonic acids are formed from nitrogenous and non nitrogenous parts of proteins respectively
There are mainly two types of amino acids :: 1. Essential amino acids and 2.Non essential amino acids Essential amino acids are not synthesised in the body and they are essential for life e.g Phenylalanine lysine methionine valine leucine etc Non essential amino acids are synthesised in the body Therefore one needs proteins containing essential amino acids in the food
Protein metabolism can be divided into two parts::
1.Endogenous Metabolism:
it means breakdown of proteins present in the living cells.
2.Exogenous Metabolism::
It means breakdown of proteins which does not exist as part of the cell protoplasm
During metabolism of protein urea ammonia creatine creatine creatinine neutral sulphur uric acid etc are formed in the body Ammonia helps to combat acidosis of blood and spares sodium and calcium ions of the body other metabolites are excreted in the urine Many acids metabolise into kreds cycle Thiamine pyridoxine and riboflavin play an important role as coenzymes in protein metabolism
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