Elucidation of immnoregulating function of casein phosphopeptide

从牛α s1-酪蛋白的胰蛋白酶消化物中纯化出一种免疫调节肽，经鉴定为牛αs1-酪蛋白的59-79位残基。序列59-79具有富含磷酸丝氨酸的区域并且被称为酪蛋白磷酸肽之一。牛β-酪蛋白也具有富含磷酸丝氨酸的区域。因此，作者分离了酪蛋白磷酸肽之一的β-酪蛋白片段1-25，从胰蛋白酶解的β-酪蛋白中获得的酪蛋白磷酸肽具有与牛αs1-酪蛋白磷酸肽相同的免疫调节作用，酪蛋白磷酸肽具有促有丝分裂活性，并通过刺激IL-5和IL-10刺激有丝分裂原诱导的细胞增殖和免疫球蛋白的产生6由小鼠脾细胞培养物中的Th 2细胞产生。口服酪蛋白磷酸肽可提高小鼠和仔猪的抗原特异性伊加和总伊加水平。此外，免疫刺激活性被确认为具有至少2个磷酸丝氨酸残基的磷酸肽，即，SerP-Leu-SerP。已经广泛报道了通过各种蛋白水解酶的作用从牛酪蛋白产生各种酪蛋白磷酸肽。因此，从牛酪蛋白酶制备的酪蛋白磷酸肽是用于增强人和牲畜中粘膜伊加应答的有益食品。

An immunomodulating peptide was purified from a trypsin digest of bovine αs1-casein and identified as residues 59-79 in bovine αs1-casein. The sequence 59-79 has a Phosphoserine-rich region and is called one of casein phosphopeptides. Bovine β-casein aloso possesses phosphoserin-rich region. Hence, the author isolated β-casein fragment 1-25, one of the casein phosphopeptides, from tryptic β-casein and confirmed that the phosphopeptide displayed the immunomodulating action as well as the casein phosphopeptide from bovine αs1-casein.The casein phosphopeptides displayed a mitogenic activity and stimulated the mitogen-induced proliferations and the immunoglobulin production via the stimulation of IL-5 and IL-6 produced from Th2 cells in mouse spleen cell cultures. The oral adminstration of casein phosphopeptides enhanced the levels of antigen-specific IgA and total IgA in mice and piglets. Moreover, the immunostimulating activity was confirmed to a phosphopeptide having at least 2 phosphoserine residues, i.e., SerP-Leu-SerP.It has been widely reported that various kinds of casein phosphopeptides are produced from bovine caseins by the action of various kinds of proteolytic enzymes. Thus, the casein phosphopeptides prepared from bovine casein digests are beneficial foodstuffs for the enhancement of mucosal IgA responses in man and livestock.