Determination of the limited trypsinolysis pathways of tumor necrosis factor-alpha and its mutant by electrospray ionization mass spectrometry.
Electrospray ionization mass spectrometry (ESI-MS) is employed to directly analyze the limited trypsinolysis products of wild-type tumor necrosis factor-alpha (wtTNF-alpha) and its mutant, M3S. To determine the charge numbers of peaks of relatively small peptides in the ESI mass spectrum of a digest, a series of sodium-adduct ion peaks of each peptide are generated by adding a small quantity of NaCl to the digest before taking the spectrum. From the monitoring of the composition of proteolytic mixture as the incubation time is lengthened, it has been learned that the proteolysis of wtTNF-alpha by trypsin occurs sequentially: Arg2, Arg6, Arg32, Arg31, and Arg44, and that M3S is strongly resistant to the proteolysis. Since the cleavage sequence of wtTNF-alpha and the mutation-induced resistance of M3S are consistent with the structural features of the proteins, we can suggest a mutant more resistant to proteolysis than M3S, which has an additional point mutation, Ala35Leu or Ala35Ile.
Center for Biofunctional Molecules and Department of Chemistry, Pohang University of Science and Technology, San 31 Hyoja Dong, Pohang, 790-784, South Korea.
Y J
YJ
Kim
S S
SS
Cha
J S
JS
Kim
N K
NK
Shin
W
W
Jeong
H C
HC
Shin
B H
BH
Oh
J H
JH
Hahn
D000595:Amino Acid Sequence; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D009154:Mutation; D014357:Trypsin / Q000494:pharmacology*; D014409:Tumor Necrosis Factor-alpha / Q000737:chemistry* / Q000378:metabolism
D014409:Tumor Necrosis Factor-alpha; D014357:Trypsin