Volume 62, 1966

Micro-ionization constants for tyrosine

Abstract

Macro-ionization constants for tyrosine at 25°C (9.21; 10.46), 60°C (8.51; 10.09) and 90°C (8.06; 10.00) have been determined from pH titration data. The use of spectrophotometric data over the pH range 9–10.5 in conjunction with the titration data has provided micro-ionization, constants at these temperatures. Representing the acidic groups in order of ionization —COOH (1), –OH (2), –NH+3(3), then (at 25°C) pkT12= 9.75, pkT13= 9.36, pkT123= 9.92, pkT132= 10.31, (60°C) 9.20, 8.61, 9.40, 9.99 and (90°C) 9.02, 8.11, 9.04, 9.95. The errors involved in the method are discussed and a comparison made with the results at 25°C obtained by other workers. The use of the data in considerations of metal-dye-aminoacid formation constants is indicated.

Article information

Article type
Paper

Trans. Faraday Soc., 1966,62, 2577-2583

Micro-ionization constants for tyrosine

E. Coates, P. G. Gardam and B. Rigg, Trans. Faraday Soc., 1966, 62, 2577 DOI: 10.1039/TF9666202577

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