Isolation and characterization of angiogenin-1 and a novel protein designated lactogenin from bovine milk.
This paper reports the isolation and characterization from bovine milk of two proteins: angiogenin-1, a recently discovered angiogenin, and lactogenin, a novel protein. Both proteins were adsorbed on and eluted closely from CM-Sepharose and Mono S. Lactogenin possessed a molecular weight (17 kDa) slightly higher than that of angiogenin-1 (15 kDa). Lactogenin had a higher ribonucleolytic (RNase) activity than angiogenin-1 towards yeast transfer RNA (tRNA). The Km values estimated for the RNase activities of angiogenin-1 and lactogenin were 51 microM and 40 microM respectively. Both were specific for poly C. The optimal pH for the RNase activities of angiogenin-1 and lactogenin was 7.75 and 7.5 respectively. Comparison of the amino acid sequences of cyanogen bromide fragments and the pyroglutaminase-treated N-terminal fragment of lactogenin with the sequence of bovine liver RNase (RNase BL4) revealed identity in residues 3-22, 24, 26-27, 37, 41-44, 46-50, 54, 56, 63, 72-80, and 83. Considerable similarity to the N-terminal sequence of angiogenin-2 was also noted. Both lactogenin and angiogenin-1 inhibited cell-free translation in a rabbit reticulocyte lysate system with an IC(50) below 100 nM.
Ye
X Y
XY
Faculty of Medicine, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong.
Cheng
K J
KJ
Ng
T B
TB
D000595:Amino Acid Sequence; D000818:Animals; D001798:Blood Proteins / Q000235:genetics; D002417:Cattle; D005260:Female; D007700:Kinetics; D008894:Milk Proteins / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D008969:Molecular Sequence Data; D008970:Molecular Weight; D014176:Protein Biosynthesis; D011506:Proteins / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D011817:Rabbits; D012156:Reticulocytes / Q000378:metabolism; D012259:Ribonuclease, Pancreatic; D012260:Ribonucleases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
D001798:Blood Proteins; D008894:Milk Proteins; D011506:Proteins; C121812:lactogenin; D012260:Ribonucleases; C046366:angiogenin; D012259:Ribonuclease, Pancreatic