Affinity of chicken cystatin for S-(carbamoylmethyl)-papain, measured by fluorescence at acidic pH.
We have characterized the interaction between S-(carbamoylmethyl)-papain and chicken cystatin by means of fluorescence titration at acidic pH. The calculated binding constant was 32 x 10(6), which is less than the tight affinity at pH 7.4 (approximately 7 x 10(10)). Results have been discussed in terms of the burial of Trp-104 of cystatin and the possible role of the charge of the carbamoylmethyl moiety.
Arroyo-Reyna
Alfonso
A
Area de Biofisicoquímica, Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, Apartado Postal, México.
Gutiérrez-Gómez
Ezequiel
E
D000818:Animals; D002645:Chickens; D015891:Cystatins / Q000737:chemistry*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D006863:Hydrogen-Ion Concentration; D010206:Papain / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013696:Temperature; D014364:Tryptophan / Q000737:chemistry
D015891:Cystatins; D014364:Tryptophan; C028596:S-carboxymethyl-papain; D010206:Papain