A Study of Human Platelet Esterases^[*]

Summary

1. Platelet esterase activity has been estimated using a manometric technique. The most suitable substrate used was tributyrin. Tributyrinase activity corresponded with DFP³² uptake by the platelet and probably reflected overall esterase activity. Evidence has been presented that this enzyme is an integral part of the platelet.

2. Platelet esterase activity rapidly diminished on storage at 4° C and was peculiarly susceptible to cell lysis. This activity may be an index of platelet viability.

3. No direct correlation could be found between platelet esterase activity and platelet aggregation.

^* This work was supported by The Australian Research Grants Committee and presented in part at the XIth Congress of the International Society of Hematology, Sydney, 1966.

• References

• 1 Ammon R, Jaarma M. Enzymes Hydrolysing Fats and Esters. The Enzymes 1959; 1: 390 Part 1
• 2 Myers D.K. Carboxyl Ester Cleavage (Survey). The Enzymes. Second Edition 1963; 4: 475
• 3 Hofstee B.H. J. Fatty Acid Esterase of Low Eserine Sensitivity and Related Enzymes. The Enzymes. Second edition 1963; 4: 485
• 4 Desnuelle P, Savary P. Specificities of Lipases. J. Lipid Res 1963; 4: 369
• 5 Alexander B. Some Biochemical, Physiological and Pathological Aspects of the Coagulation Mechanism. Blood Cells and Plasma Proteins: Their State in Nature. Ed. Tullis J.L. Acad. Press: New York; 1953: 75
• 6 Vincent D, Maupin B, Marques -Vincent M.C. Sur Les Esterases Des Plaquettes Du Sang Humain (Cholinesterase et Arylesterase). Soc. Biologie 1962; 156: 34
• 7 Aldridge W.N. Serum Esterases. Biochem. J 1953; 53: 110
• 8 Mounter L.A, Whittaker V.P. The Hydrolysis of Esters of Phenol by Cholinesterases and Other Esterases. Biochem. J 1953; 54: 551
• 9 Zucker M.B, Ley A.B, Mayer K. Studies on Platelet Life Span and Platelet Depots by Use of DFP³² . J. Lab. clin. Med 1961; 58: 405
• 10 Bithell T.C, Athens J.W, Cartwright G.E, Wintrobe M.M. Radioactive Diisopropyl Fluorophosphate as a Platelet Label : An Evaluation of in vitro and in vivo Techniques. Blood 1967; 29: 354
• 11 Webb E.C. The Action of Alkyl Fluorophosphonates on Esterases and other Enzymes. Biochem. J 1948; 42: 96
• 12 Saltzman E.W, Chambers D.A. Inhibition of ADP-induced Platelet Aggregation by Substituted Amino Acids. Nature (Lond.) 1964; 204: 698
• 13 O’Brien J.R. Platelet Aggregation - Some Results from a New Method of Study. J. clin. Path 1962; 15: 452
• 14 Born G.V.S, Cross M.J. The Aggregation of Blood Platelets. J. Physiol 1963; 168: 178
• 15 Haslam R.J. Role of Adenosine Diphosphate in the Aggregation of Human Blood Platelets by Thrombin and by Fatty Acids. Nature (Lond.) 1964; 202: 765
• 16 Armstrong J.H.D, Myers D.V, Verpoorte J.A, Edsall J.T. Purification and Properties of Human Erythrocyte Carbonic Anhydrases. J. biol. Chem 1966; 241: 5137
• 17 Baldini M, Costea N, Dameshek W, Lemouro A. The Viability of Stored Human Platelets. Blood 1960; 16: 1669
• 18 Kilburn E.P, Firkin B.G. Unpublished observations.
• 19 Rozenberg M.C, Thesis M.D. University of Sydney 1965
• 20 Cooper I.A, Howard M.A, Firkin B.G. Unpublished observations 1967.
• 21 Brinkhous K.M, Read M.S, Mason R.G. Plasma Thrombocyte - Agglutimating Activity and Fibrinogen. Synergism with Adenosine Diphosphate. Lab. Invest 1965; 14: 335
• 22 O'Sullivan W.J, Morrison J.F. The Effect of Trace Metal Contaminants and EDTA on the Velocity of Enzyme-Catalysed Reactions — Studies on ATP: Creatine Phosphotransferase. Biochem. biophys. Acta (Amst.) 1963; 77: 142
• 23 Whitlam R. Transport and Diffusion in Red Blood Cells. 1964. Edward Arnold: London;