Presence of multiple forms of peptidase inhibitors in rat milk

Radhakrishna Rao, K. Lam, A. F. Philipps, C. Williams, M. Lake, O. Koldovský

Research output: Contribution to journalArticle

30 Citations (Scopus)

Abstract

Peptides such as somatostatin (SS14), epidermal growth factor (EGF), transforming growth factor-α (TGFα), and insulin-like growth factors (IGF-I and IGF-II) are present in breast milk from various species, and their significance in the developing gastrointestinal tract has been suggested. Our recent studies have indicated that rat milk soluble fraction (RMSF) protects SS14 in the gastrointestinal lumen by inhibiting in vitro the luminal peptidolysis. In the present studies, we have shown that RMSF inhibited in vitro degradation by midjejunal luminal flushings of suckling rats of125I-labeled somatostatin 14[Tyr11], EGF, TGFα, IGF-I and IGF-II, as well as trypsin activity in vitro against benzoyl-L-αrginyl-/?-nitroanilide. The inhibitory factors present in the RMSF were further fractionated by gel filtration on Sephadex G100, ion-exchange chromatography on DEAE-Sephadex, and fast protein liquid chromatography (FPLC). Gel filtration of Sephadex G100 separated RMSF into three peaks of proteins: Gl, G2, and G3; peptidase inhibitor activities were present exclusively in Gl. Ion-exchange chromatography on DEAE-Sephadex column resolved peptidase inhibitory activity (Gl) into three different peaks, Dl, D2, and D3, eluted at sodium chloride concentrations of 0.05 M, 0.1 M, and 0.2 M, respectively. Further purification of D2 by FPLC resulted in a fraction rich in peptidase inhibitory activity, which was essentially free of trypsin inhibitory activity. Results indicate the presence of at least three peptidase inhibitors in rat milk, which may play a role in the protection of milk-borne peptides in the gastrointestinal lumen.

Original languageEnglish (US)
Pages (from-to)414-420
Number of pages7
JournalJournal of pediatric gastroenterology and nutrition
Volume17
Issue number4
DOIs
StatePublished - Jan 1 1993

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Protease Inhibitors
Milk
Insulin-Like Growth Factor I
DEAE-Dextran
Insulin-Like Growth Factor II
Ion Exchange Chromatography
Transforming Growth Factors
Somatostatin
Epidermal Growth Factor
Liquid Chromatography
Trypsin
Gel Chromatography
Peptide Hydrolases
Peptides
Proteins
Human Milk
Sodium Chloride
Gastrointestinal Tract
In Vitro Techniques

All Science Journal Classification (ASJC) codes

  • Pediatrics, Perinatology, and Child Health
  • Gastroenterology

Cite this

Presence of multiple forms of peptidase inhibitors in rat milk. / Rao, Radhakrishna; Lam, K.; Philipps, A. F.; Williams, C.; Lake, M.; Koldovský, O.

In: Journal of pediatric gastroenterology and nutrition, Vol. 17, No. 4, 01.01.1993, p. 414-420.

Research output: Contribution to journalArticle

Rao, Radhakrishna ; Lam, K. ; Philipps, A. F. ; Williams, C. ; Lake, M. ; Koldovský, O. / Presence of multiple forms of peptidase inhibitors in rat milk. In: Journal of pediatric gastroenterology and nutrition. 1993 ; Vol. 17, No. 4. pp. 414-420.
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