Brines R D, Brock J H
Biochim Biophys Acta. 1983 Sep 13;759(3):229-35. doi: 10.1016/0304-4165(83)90317-3.
The susceptibility of lactoferrin in bovine colostrum and human milk to digestion by trypsin and chymotrypsin has been investigated. Neither enzyme had much effect on the lactoferrin-mediated antimicrobial activity of human milk, and the iron binding capacity of lactoferrin in the milk was only slightly reduced. Likewise both enzymes had only a slight effect on the iron-binding capacity of purified lactoferrin. Although iron-free (apo)lactoferrin was slightly more susceptible to digestion, especially by chymotrypsin, than the iron-saturated form, the difference was much less than has been found in earlier studies with other proteins of the transferrin class. In contrast, trypsin destroyed the antimicrobial activity of bovine colostrum, and, in line with earlier studies, appreciably reduced the iron-binding capacity of both colostrum and purified bovine apolactoferrin. Bovine iron-saturated lactoferrin was more resistant to digestion. The unusual resistance of human apolactoferrin to proteolysis may reflect an evolutionary development designed to permit its survival in the gut of the infant.
已对牛初乳和人乳中的乳铁蛋白对胰蛋白酶和糜蛋白酶消化作用的敏感性进行了研究。这两种酶对人乳铁蛋白介导的抗菌活性影响不大，且人乳中乳铁蛋白的铁结合能力仅略有降低。同样，这两种酶对纯化乳铁蛋白的铁结合能力也只有轻微影响。尽管无铁（脱铁）乳铁蛋白比铁饱和形式的乳铁蛋白对消化作用稍敏感，尤其是对糜蛋白酶，但这种差异远小于早期对转铁蛋白类其他蛋白质的研究中所发现的差异。相比之下，胰蛋白酶破坏了牛初乳的抗菌活性，并且与早期研究一致，显著降低了初乳和纯化的牛脱铁乳铁蛋白的铁结合能力。牛铁饱和乳铁蛋白对消化作用更具抗性。人脱铁乳铁蛋白对蛋白水解的异常抗性可能反映了一种进化发展，旨在使其能在婴儿肠道中存活。
