title: Hydrolysis of substance P in the presence of the osteosarcoma cell line SaOS-2: release of free amino acids.
abstract: The possible hydrolysis of substance P (Arg-Pro-Lys-Pro-Gln-Gln-Phe-Phe-Gly-Leu-Met) in presence of the osteoblastic cell line SaOS-2 was measured by capillary electrophoresis coupled to mass detection. The results obtained indicate that a very rapid disappearance of the intact undecapeptide was associated to a slower appearance of seven of its eight component amino acids. These results can be interpreted as indicating that an extremely fast hydrolysis of substance P by endopeptidases, which released peptidic by-products, was followed by a noticeably slower secondary degradation which released free amino acids. In decreasing quantitative importance, these phenomena appear to originate by the hydrolysis of the Pro(4)-Gln(5) bond, followed by C-terminal sequential degradation of the Arg(1)-Pro(4) tetrapeptide; by the hydrolysis of or Phe(7)-Phe(8) bond (or, possibly, of Gln(6)-Phe(7)) leading to release of free Phe and Gln; by hydrolysis of the Gly(9)-Leu(10) bond with subsequent release of Met and Leu. Results obtained appear to be compatible with the expression by SaOS-2 cells of enzymes already known to catalyze substance P hydrolysis, together with an apparent low efficiency of aminopeptidases. Because of the activity of C-terminal fragments on NK1 receptors, the delay between primary hydrolysis of substance P and secondary hydrolysis of its peptidic fragments indicated by the data shown implies a possible persistence of substance P physiological effects even after degradation of the intact peptide.
authors.affiliation: Dipartimento di Chimica Generale ed Inorganica, Chimica Analitica, Chimica Fisica, Università degli Studi di Parma, Parma, Italy.
authors.forename: Antonella
authors.initials: A
authors.lastname: Cavazza
authors.forename: Mario
authors.initials: M
authors.lastname: Marini
authors.forename: L Giorgio
authors.initials: LG
authors.lastname: Roda
authors.forename: Umberto
authors.initials: U
authors.lastname: Tarantino
authors.forename: Angela
authors.initials: A
authors.lastname: Valenti
mesh_terms: D045744:Cell Line, Tumor; D006801:Humans; D006868:Hydrolysis; D012516:Osteosarcoma / Q000378:metabolism; D013373:Substance P / Q000378:metabolism*
chemical_list: D013373:Substance P