title: Proteolytic activity of bovine lactoferrin.
abstract: Bovine lactoferrin catalyzes the hydrolysis of synthetic substrates (i.e., Z-aminoacyl-7-amido-4-methylcoumarin). Values of Km and kcat for the bovine lactoferrin catalyzed hydrolysis of Z-Phe-Arg-7-amido-4-methylcoumarin are 50 microM and 0.03 s(-1), respectively, the optimum pH value is 7.5 at 25 degrees C. The bovine lactoferrin substrate specificity is similar to that of trypsin, while the hydrolysis rate is several orders of magnitude lower than that of trypsin. The bovine lactoferrin catalytic activity is irreversibly inhibited by the serine-protease inhibitors PMSF and Pefabloc. Moreover, both iron-saturation of the protein and LPS addition strongly inhibit the bovine lactoferrin activity. Interestingly, bovine lactoferrin undergoes partial auto-proteolytic cleavage at positions Arg415-Lys416 and Lys440-Lys441. pKa shift calculations indicate that several Ser residues of bovine lactoferrin display the high nucleophilicity required to potentially catalyze substrate cleavage. However, a definitive identification of the active site awaits further studies.
authors.affiliation: Dipartimento di Biologia di Base ed Applicata, Universita' di L'Aquila, Coppito, 67010, L'Aquila, Italy.
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Massucci
authors.forename: Francesco
authors.initials: F
authors.lastname: Giansanti
authors.forename: Giovanna
authors.initials: G
authors.lastname: Di Nino
authors.forename: Manola
authors.initials: M
authors.lastname: Turacchio
authors.forename: Maria Federica
authors.initials: MF
authors.lastname: Giardi
authors.forename: Dario
authors.initials: D
authors.lastname: Botti
authors.forename: Rodolfo
authors.initials: R
authors.lastname: Ippoliti
authors.forename: Beatrice
authors.initials: B
authors.lastname: De Giulio
authors.forename: Barbara
authors.initials: B
authors.lastname: De Giulio
authors.forename: Rosa Anna
authors.initials: RA
authors.lastname: Siciliano
authors.forename: Rosa
authors.initials: R
authors.lastname: Siciliano
authors.forename: Giovanna
authors.initials: G
authors.lastname: Donnarumma
authors.forename: Piera
authors.initials: P
authors.lastname: Valenti
authors.forename: Alessio
authors.initials: A
authors.lastname: Bocedi
authors.forename: Fabio
authors.initials: F
authors.lastname: Polticelli
authors.forename: Paolo
authors.initials: P
authors.lastname: Ascenzi
authors.forename: Giovanni
authors.initials: G
authors.lastname: Antonini
mesh_terms: D000818:Animals; D002417:Cattle; D002846:Chromatography, Affinity; D006801:Humans; D006867:Hydrolases / Q000378:metabolism*; D007781:Lactoferrin / Q000737:chemistry / Q000378:metabolism*; D008970:Molecular Weight; D012694:Serine / Q000378:metabolism; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D012694:Serine; D006867:Hydrolases; D007781:Lactoferrin