J. Fernandez et al., Purification and properties of two intracellular aminopeptidases produced by Brevibacterium linens SR3, INT DAIRY J, 10(4), 2000, pp. 241-248
Two aminopeptidases, designated as aminopeptidase I (API) and aminopeptidas
e II (APII), were isolated from the disrupted cells of Brevibacterium linen
s SR3 and purified to homogeneity by a combination of Phenyl-Sepharose, DEA
E-Sepharose, Q-Sepharose and Sepharose CL-6B chromatography. Optimal temper
ature for enzymatic activity was 45 degrees C for API and 37 degrees C for
APII, and the pH optimum was found to be 8.5 for API and 8.0 for APII. Diva
lent metals ions like Co2+ and Ni2+ increased enzymatic activity while Ca2, Cu2+ and Fe2+ had an inhibitory effect. The enzymes were strongly inhibit
ed by EDTA, 1,10-Phenantroline and cysteine, indicating that both aminopept
idases were metalloenzymes. The K-m values of API and APII for L-leucine-p-
nitroanilide were 1.0 and 0.25 mM, respectively. Native molecular masses of
aminopeptidases I and II were 80 and 220 kDa after gel filtration chromato
graphy while molecular masses of 14 and 18 kDa, were seen, after SDS-polyac
rylamide gel electrophoresis. (C) 2000 Elsevier Science Ltd. All rights res
erved.