Analytical Biochemistry 1983-04-01

An improved cathepsin-D substrate and assay procedure.

N Agarwal, D H Rich

Index: Anal. Biochem. 130 , 158, (1983)

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Abstract

Ten analogs of the peptide A-Phe(NO2)-Phe-Val-Leu-B were synthesized and tested as substrates for cathepsin D and pepsin. The best substrate found for cathepsin D, Phe-Ala-Ala-Phe(NO2)-Phe-Val-Leu-OM4P (kcat = 2.9 s-1; Km = 7.1 microM), has the largest kcat/Km value (408 mM-1 s-1) reported to date for this enzyme. The effect of peptide structure on solubility and kinetic parameters is discussed. The peptide provides a useful new substrate for continuous assay of cathepsin D.