Purification and partial characterization of a novel human platelet aggregation factor in the extracellular products of Streptococcus mitis, strain Nm-65.
A human blood platelet aggregation factor was purified from the extracellular products (ECP) of Streptococcus mitis, strain Nm-65 by sequential chromatography on DEAE-Sepharose CL-6B, hydroxyapatite and Superdex 75 columns. The purified factor (S. mitis-derived human platelet aggregation factor, Sm-hPAF) gave a single band with a molecular weight of 66 kDa on SDS-polyacrylamide gel electrophoresis (SDS-PAGE). Sm-hPAF showed a peak absorption at 278 nm and an isoelectric point of around 8.5. Chemical analyses revealed that Sm-hPAF contained no sugars and that its first 15 amino-terminal amino acid residues were H-DEQGNRPVETENIAR. Platelet aggregation activity of Sm-hPAF was abolished by heating at 45 degrees C for 10 min. Platelet aggregation by Sm-hPAF was accompanied by a release of prostaglandin E2 (PGE2) in a dose-dependent manner. The platelet aggregation was not inhibited by either prostaglandin E1 (PGE1) or Gly-Arg-Gly-Asp-Ser (GRGDS), that inhibit the platelet aggregation induced by collagen. Twenty (77%) platelet rich-plasma (PRP) specimens derived from 26 healthy volunteers were aggregated by Sm-hPAF, but the remaining 6 (23%) were not reactive. A preliminary study suggested the presence of an inhibitory factor against Sm-hPAF in the plasma from a non-reactive donor.
Ohkuni
H
H
Division of Immunology, Nippon Medical School, Kawasaki, Japan. h-okuni@nms.ac.jp
Todome
Y
Y
Okibayashi
F
F
Watanabe
Y
Y
Ohtani
N
N
Ishikawa
T
T
Asano
G
G
Kotani
S
S
D000328:Adult; D001426:Bacterial Proteins / Q000737:chemistry* / Q000302:isolation & purification* / Q000494:pharmacology; D005110:Extracellular Space / Q000737:chemistry* / Q000382:microbiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010972:Platelet Activating Factor / Q000737:chemistry* / Q000302:isolation & purification* / Q000494:pharmacology; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D013291:Streptococcus / Q000737:chemistry* / Q000276:immunology
D001426:Bacterial Proteins; D010972:Platelet Activating Factor; D010975:Platelet Aggregation Inhibitors