Chemical and physical characterization of a proline-rich polypeptide from sheep colostrum

Abstract

A proline-rich polypeptide isolated from sheep colostrum is described. The molecular weight of the polypeptide determined by gel filtration is 17 200. However, in the presence of guanidinium chloride the molecular weight found is about 6000. The polypeptide contains about 22% of proline, a high proportion of non-polar amino acids, a low percentage of glycine, and no alanine, arginine and cysteine residues. The only N-terminal amino acid found is leucine. C.d. spectra in water and in 50% (v/v) trifluoroethanol suggest the presence of block sequences of proline residues forming helices of polyproline II type. The proline-rich polypeptide is soluble at 4 degrees C but is reversibly precipitated on warming to room temperature. Maximal precipitation is observed at pH 4.6 and at ionic strength above 0.6. The precipitation depends on the concentration of the polypeptide. No effect of other proteins, Ca2+ and Zn2+ ions on the precipitation of the polypeptide was found. The proline-rich polypeptide is not an amphipathic protein. The lack of effect of the polypeptide on proteolytic enzymes ruled out the possibility that it is an inhibitor of proteinases.

Colostrinin Decreases Hypersensitivity and Allergic Responses to Common Allergens

“…CLN-conditioned mice produced significantly less IgE against RWE and HDME than did the sensitized, non-conditioned mice, in agreement with the immunomodulatory effects of CLN [2, 3, 6, 7]. Here, we further evaluated the impact of CLN on airway eosinophilia induced by common allergens (RWE, HDME).…”

“…CLN is a mixture of low-molecular-weight, proline-rich peptides [2, 4, 5] that has been administered to individuals with age-associated dementia [12,13,14]. Whether CLN induces allergic responses or modulates responses to other allergens has never been investigated.…”

“…CLN is purified from pre-milk fluid (colostrum) collected from mothers during the first 24 h after giving birth [1,2,3,4,5]. It has been shown that CLN is an important immune modulator that induces maturation and differentiation of murine thymocytes [3, 6], promotes peripheral blood leukocyte proliferation and induces cytokine production [3, 7].…”

Eggs as a Very Promising Source of Biomedical and Nutraceutical Preparations: A Review

“…The complex, later referred to as Colostrinin®, is found in colostrum in a form bound with a fraction of immunoglobulins IgG2, which indicates its immunotropic properties [55]. Colostrinin (CLN) is a strong inductor of secretion of cytokines so vital for the immune system, i.e.…”

Le colostrum, un lait particulièrement riche en de nombreux composants : peut-on en déceler la présence dans les livraisons de lait de vache ?

“…De 38 kOa, ce polypeptide baptisé PRP (proline rich polypeptide) a ensuite été estimé à 18 kOa, et s'est révélé constitué de sous-unités de 6 kDa liées de façon non covalente [52,153]. Son action sur la maturation des thymocytes murins en cellules T helper ou T suppressives [158,159] s'est révélée contenue dans un nonapeptide obtenu par digestion chymotrypsique et plus particulièrement dans les six derniers acides aminés de l'extrêmité carboxy-terminale [53].…”