In studies of protein digestion and of the nature and fate of the digestion products, methods for measuring the amounts of amino acids present in blood and other parts of the body are indispensable tools.
The first was the "nitrous acid method" which depends on the reaction: RCH(NH 2 )COOH+HNO 2 = RCH(OH)COOH+H 2 O+N 2 The N 2 gas is a measure of the amount of amino acid present. The reaction is not entirely specific for amino acids, because other amines with NH2 groups also react; but such amines are usually not present in important amounts or can be removed.
A later and more specific method depends on reaction with a mild oxidizing agent called ninhydrin. Its effect is indicated by the equation: RCH(NH 2 )COOH+O= RCHO+NH 3 +CO 2 The analysis consists merely of heating the mixture for a few minutes and measuring the CO 2 evolved. This reaction is so specific for free amino acids that it serves to pick out and measure them in the most diverse mixtures of other amines, organic acids, peptides and other biological products.
Subscribe to:
Post Comments (Atom)
No comments:
Post a Comment