Structural and functional characterization of vitronectin-derived RGD-containing peptides from human hemofiltrate.
Bioactive peptides derived from the adhesive plasma protein vitronectin are present at submicromolar concentrations in human hemofiltrate of patients with renal diseases and were isolated by a combination of high-efficiency chromatographic steps. The structural and functional properties of these peptides were characterized. Sequencing and mass spectrometry revealed the existence of peptide isoforms (5-6 kDa) which corresponded to the N-terminus (residues 1 to 44-50) of vitronectin. The isolated peptides bound directly to plasminogen-activator inhibitor-1 (PAI-1) and were effective competitors of the interaction of PAI-1 with isolated intact vitronectin or extracellular matrix. These functional properties were indistinguishable from the binding properties of a recombinant fusion protein containing residues 1-52 of vitronectin linked to a portion of glutathione S-transferase, expressed in Escherichia coli. Peptides containing the RGD sequence of vitronectin competed for vitronectin binding to the alpha v beta 3 integrin. No indication for direct growth-factor binding was noted, whereas natural peptides were found associated with PAI-1 as the major binding protein in plasma. These data demonstrate that functionally active vitronectin-derived peptides are released by unknown protease(s) from the mature protein and that these peptides are identical, in terms of activity, to recombinant vitronectin fragments. These natural peptides may interact with active PAI-1 in plasma or at extravascular sites and thereby interfere with established biological functions of intact vitronectin.
Lower Saxony Institute of Peptide Research, Hannover, Germany.
L
L
Ständker
A
A
Enger
P
P
Schulz-Knappe
K D
KD
Wohn
M
M
Germer
M
M
Raida
W G
WG
Forssmann
K T
KT
Preissner
D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites; D017931:DNA Primers / Q000235:genetics; D006440:Hemofiltration; D006801:Humans; D007676:Kidney Failure, Chronic / Q000097:blood; D015394:Molecular Structure; D009842:Oligopeptides / Q000302:isolation & purification; D010446:Peptide Fragments / Q000097:blood / Q000737:chemistry / Q000302:isolation & purification; D017395:Plasminogen Activator Inhibitor 1 / Q000378:metabolism; D011485:Protein Binding; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D019096:Vitronectin / Q000097:blood / Q000737:chemistry* / Q000302:isolation & purification
D017931:DNA Primers; D009842:Oligopeptides; D010446:Peptide Fragments; D017395:Plasminogen Activator Inhibitor 1; D011993:Recombinant Fusion Proteins; D019096:Vitronectin; C047981:arginyl-glycyl-aspartic acid