title: Peptidomic analysis of skin secretions from the bullfrog Lithobates catesbeianus (Ranidae) identifies multiple peptides with potent insulin-releasing activity.
abstract: Using a combination of reversed-phase HPLC and electrospray mass spectrometry, peptidomic analysis of norepinephrine-stimulated skin secretions of the American bullfrog Lithobates catesbeianus Shaw, 1802 led to the identification and characterization of five newly described peptides (ranatuerin-1CBb, ranatuerin-2CBc, and -CBd, palustrin-2CBa, and temporin-CBf) together with seven peptides previously isolated on the basis of their antimicrobial activity (ranatuerin-1CBa, ranatuerin-2CBa, brevinin-1CBa, and -1CBb, temporin-CBa, -CBb, and -CBd). The abilities of the most abundant of the purified peptides to stimulate the release of insulin from the rat BRIN-BD11 clonal β cell line were evaluated. Ranatuerin-2CBd (GFLDIIKNLGKTFAGHMLDKIRCTIGTCPPSP) was the most potent peptide producing a significant stimulation of insulin release (119% of basal rate, P<0.01) from BRIN-BD11 cells at a concentration of 30nM, with a maximum response (236% of basal rate, P<0.001) at a concentration of 3μM. Ranatuerin-2CBd did not stimulate release of the cytosolic enzyme, lactate dehydrogenase at concentrations up to 3μM, indicating that the integrity of the plasma membrane had been preserved. Brevinin-1CBb (FLPFIARLAAKVFPSIICSVTKKC) produced the maximum stimulation of insulin release (285% of basal rate, P<0.001 at 3μM) but the peptide was cytotoxic at this concentration.
authors.affiliation: Department of Biochemistry, United Arab Emirates University, 17666 Al-Ain, United Arab Emirates.
authors.forename: Milena
authors.initials: M
authors.lastname: Mechkarska
authors.forename: Opeolu O
authors.initials: OO
authors.lastname: Ojo
authors.forename: Mohammed A
authors.initials: MA
authors.lastname: Meetani
authors.forename: Laurent
authors.initials: L
authors.lastname: Coquet
authors.forename: Thierry
authors.initials: T
authors.lastname: Jouenne
authors.forename: Yasser H A
authors.initials: YH
authors.lastname: Abdel-Wahab
authors.forename: Peter R
authors.initials: PR
authors.lastname: Flatt
authors.forename: Jay D
authors.initials: JD
authors.lastname: King
authors.forename: J Michael
authors.initials: JM
authors.lastname: Conlon
mesh_terms: D000595:Amino Acid Sequence; D029845:Amphibian Proteins / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D012634:Bodily Secretions / Q000737:chemistry*; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D002851:Chromatography, High Pressure Liquid; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000187:drug effects* / Q000378:metabolism; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010455:Peptides / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D020033:Protein Isoforms / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D011506:Proteins / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D011892:Rana catesbeiana / Q000378:metabolism*; D051381:Rats; D012867:Skin / Q000378:metabolism*; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D029845:Amphibian Proteins; D023181:Antimicrobial Cationic Peptides; D007328:Insulin; D010455:Peptides; D020033:Protein Isoforms; D011506:Proteins; C121230:ranatuerin; C104501:temporin; C078413:brevinin-1 protein, Rana