Publisher Summary This chapter discusses the problem of determining the nature and number of the component amino acid residues of proteins and related compounds. Many of the techniques for separating amino acids are also suitable for the much more difficult tasks of separating the peptides resulting from the partial hydrolysis of proteins; some of these techniques have in fact been developed with this as their primary aim. Studies of partial hydrolysis products are likely to be very fruitful for the detailed elucidation of protein structure. That reliable methods of amino acid analysis should be available is important also for agricultural, clinical, and nutritional work. In these disciplines, accuracy may often profitably be sacrificed in favor of speed and simplicity of manipulation. In connection with metabolic studies making use of isotopes it is desirable that methods be available for isolating every amino acid in a high state of purity and from all kinds of biological material. Special methods are also required for checking the purity of pure amino acids. The chapter describes the advances that have been made in this branch of protein chemistry during the past 15 years.

Analytical Chemisty of the Proteins

Die Trennung und Bestimmung der natürlichen Aminosäuren

Auf der Basis einer von Baernstein angegebenen Methode wurde ein Mikroverfahren zur gleichzeitigen Bestimmung von Methionin uber Thiolacton und „fluchtiges Methyl“, von Cystin sowie von Schwefelwasserstoff- und Sulfitschwefel entwickelt, das die Bestimmung dieser Fraktionen in Proteinen, Gesamtlebensmitteln und anderen organischen Substanzen gestattet. Ein Vergleich mit anderen Verfahren erwies die Zuverlassigkeit und Leistungsfahigkeit dieser Methode.

Untersuchungen zur Bestimmung von Methionin

A simple spectrophotometric method for the determination of methionine is described. The method is based on the inhibitory activity of methionine on the reaction of lactic acid withp-hydroxydiphenyl. The method was developed with mixtures containing known amounts of lactic acid in concentrated sulphuric acid to which increasing amounts of methionine were added. The intensity of colour obtained decreased in proportion to the amount of methionine added (in the range 5–45μg). The method is recommended for analysis of samples which contain methionine in the presence of different amino-acids.

Robert C. Shultz

Papers

A color reaction for methionine.