Blood, 1958, Vol. 13, No. 6, pp. 589-598.
© 1958 American Society of Hematology, Inc.
Calcium-Lipid Complexes in Human Platelets
DONALD F. HOELZL WALLACH 1,
DOUGLAS M. SURGENOR 1, and
BARBARA B. STEELE 1
1 Department of Biological Chemistry, Harvard Medical School and Protein
Foundation, Boston, Mass.
Carefully washed human platelets contain calcium in an unusual state
of chemical combination. Platelet calcium is non-ionic and is not exchangeable
with ionic Ca45. On extraction of platelets with lipid solvents, the calcium
separates with the phospholipids. The calcium-lipid complex thus obtained
does not undergo any exchange with radioactive calcium. Study of other
properties of platelets reveals that the clot-promoting activity of platelets
(activated by antihemophilic factor and plasma thromboplastin component)
also separates into the lipid fraction. Preliminary observations are reported on the nature of platelet lipids as revealed by paper chromatography
and paper electrophoresis in solvents of low dielectric constant. Small amounts
of proteolipid have been isolated from the lipid extracts. The unique calciumlipid complex is thought to originate in the cell membrane of the platelet.
Submitted on October 2, 1957
Accepted on January 15, 1958