Ribonuclease, cell-free translation-inhibitory and superoxide radical scavenging activities of the iron-binding protein lactoferrin from bovine milk.
The purpose of this study was to characterize the ribonuclease (RNase) and cell-free translation-inhibitory activities of lactoferrin isolated from bovine milk. It was found that bovine lactoferrin exhibited ribonucleolytic activity toward yeast transfer RNA in a dose-dependent manner. The pH optimum for this RNase activity was in the vicinity of 7.5. Lactoferrin exerted RNase activity on poly C with an activity of 2.15 U/mg. No activity was detected toward poly A, poly G, and poly U. The milk protein inhibited cell-free translation in rabbit reticulocyte lysate with an IC50 of 9.6 microM. The protein was devoid of N-glycosidase activity characteristic of ribosome inactivating proteins which also possess RNase and cell-free translation-inhibitory activities. It inhibited superoxide radical formation.
Ye
X Y
XY
Department of Biochemistry, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories.
Wang
H X
HX
Liu
F
F
Ng
T B
TB
D000818:Animals; D002417:Cattle; D002474:Cell-Free System; D005260:Female; D016166:Free Radical Scavengers / Q000378:metabolism*; D066298:In Vitro Techniques; D007781:Lactoferrin / Q000378:metabolism*; D008892:Milk / Q000378:metabolism*; D014176:Protein Biosynthesis; D011500:Protein Synthesis Inhibitors / Q000378:metabolism; D012343:RNA, Transfer / Q000378:metabolism; D011817:Rabbits; D012156:Reticulocytes / Q000378:metabolism; D012260:Ribonucleases / Q000378:metabolism*; D013481:Superoxides / Q000378:metabolism
D016166:Free Radical Scavengers; D011500:Protein Synthesis Inhibitors; D013481:Superoxides; D012343:RNA, Transfer; D012260:Ribonucleases; D007781:Lactoferrin