Xylosyltransferase I acceptor properties of fibroblast growth factor and its fragment bFGF (1-24).
Human basic fibroblast growth factor (bFGF) is a heparin-binding growth factor containing a G-S-G-motif which is a potential recognition sequence of xylosyltransferase I (XT-I). Here, we show that the recombinant human bFGF was xylosylated in vitro by human XT-I and that the fragment bFGF (1-24) is a good XT-I acceptor (K(m) = 20.8 microM for native XT-I and K(m) = 22.3 microM for recombinant XT-I). MALDI and MALDI-PSD time-of-flight mass spectrometric analyses of the xylosylated bFGF protein demonstrate the transfer of xylose to the serine residue of the G-S-G-motif in the amino terminal end of bFGF. The peptide bFGF (1-24) is well suitable as an acceptor substrate for XT-I and can be used in a radiochemical assay to measure the XT-I activity in cell culture supernatant and human body fluids, respectively. Furthermore, we could demonstrate that the XT-I interacts strongly with heparin and that this glycosaminoglycan is a predominantly non-competitive inhibitor of the enzyme using the fragment bFGF (1-24) as xylose acceptor.
Kuhn
Joachim
J
Institut für Laboratoriums- und Transfusionsmedizin, Herz- und Diabeteszentrum Nordrhein-Westfalen, Universitätsklinik der Ruhr-Universität Bochum, Bad Oeynhausen, Germany. jkuhn@hdz-nrw.de
Schnölzer
Martina
M
Schön
Sylvia
S
Müller
Sandra
S
Prante
Christian
C
Götting
Christian
C
Kleesiek
Knut
K
D000595:Amino Acid Sequence; D001665:Binding Sites; D004789:Enzyme Activation; D016222:Fibroblast Growth Factor 2 / Q000737:chemistry*; D008969:Molecular Sequence Data; D010430:Pentosyltransferases / Q000737:chemistry*; D010446:Peptide Fragments / Q000737:chemistry; D011485:Protein Binding; D000097608:UDP Xylose-Protein Xylosyltransferase
D016222:Fibroblast Growth Factor 2; D010430:Pentosyltransferases; D010446:Peptide Fragments; D000097608:UDP Xylose-Protein Xylosyltransferase