Platelet aggregation inducing substance
A platelet aggregation inducing substance containing as an active ingredient a polypeptide having a peptide fragment represented by formula (1) (component A): -(Pro-X-Gly) n - (1) wherein X represents Pro or Hyp; and n represents an integer of from 20 to 5,000.
1. A method of inducing platelet aggregation, comprising adding, in a solution form, to blood or platelet-rich plasma, an un-crosslinked polypeptide having a peptide fragment (component A) represented by formula (1):
-(Pro-X-Gly) n - (1)
where n represents an integer of from 20 to 5,000, and wherein the peptide of formula (1) is selected from the group consisting of: (Pro-Pro-Gly)- (Component B) and -(Pro-Hyp-Gly)- (Component C), wherein the molar ratio of the Component B:Component C in said peptide fragment is 10/90 to 0/100, and
wherein said un-crosslinked polypeptide is capable of inducing said platelet aggregation even in the presence of an inhibitory amount of aspirin, as compared to collagen.
2. The method according to claim 1 , wherein the polypeptide further comprises, as a component D, at least one selected from the group consisting of a peptide unit represented by formula (4), a peptide unit represented by formula (5) and a peptide fragment containing at least one of the peptide units:
—(Y 1 —Y 2 -Gly)- (4)
-(Pro-Z 1 -Gly-Z 2 -Ala-Gly)-(SEQ ID NO:13) (5)
wherein Y 1 represents Asp or Glu, which may have a carboxyl group at the γ-position; Y 2 represents Pro or Hyp; Z 1 represents Gln, Asn, Leu, He, Val or Ala; Z 2 represents Ile or Leu, and the peptide unit represented by formula (5) is selected from the group consisting of SEQ ID NO:1, SEQ ID NO:2, SEQ ID NO:3, SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:6, SEQ ID NO:7, SEQ ID NO:8, SEQ ID NO:9, SEQ ID NO:10, SEQ ID NO:11 and SEQ ID NO:12.
3. The method according to claim 2 , wherein a molar ratio of the peptide fragment (component A) to the component D is in a range of from 99/1 to 30/70.
4. The method according to claim 1 , wherein the polypeptide exhibits positive Cotton effect at a wavelength of from 220 to 230 nm and negative Cotton effect at a wavelength of from 195 to 205 nm in a circular dichroic spectrum.
5. The method according to claim 1 , wherein the polypeptide has a molecular weight in a range of from 10,000 to 500,000,000.
6. The method according to claim 1 , wherein the polypeptide has a particle diameter in a range of from 0.01 to 1,000 μm.
7. The method according to claim 1 , wherein the polypeptide has a viscosity in a range of from 10 to 10,000 mPa·s, wherein the viscosity is measured for a 1 wt % aqueous solution of the polypeptide under a condition of 20° C. with an E-type viscometer.
8. The method according to claim 1 , wherein the polypeptide is added in presence of aspirin.