Development of enzymes of glycolysis and gluconeogenesis in human fetal liver.

The activities of two key enzymes of glycolysis and two key enzymes of gluconeogenesis were measured in liver samples from 44 human fetuses ranging in gestational age from 20 weeks to term, from infants to 10 years and from adults from 21 to 58 years. Specific activities of both gluconeogenic enzymes, fructose-1,6-biphosphatase and phosphoenolpyruvate carboxykinase, increased throughout the period of fetal development examined, and rose to near adult levels after birth. The activities of both glycolytic enzymes, phosphofructokinase 1 and pyruvate kinase, were lower in fetal than in pediatric and adult samples.

Heparin cofactor II. Purification and properties of a heparin-dependent inhibitor of thrombin in human plasma.

We have isolated a previously unrecognized heparin-dependent inhibitor of thrombin from human plasma. The inhibitor, designated heparin cofactor II (HCII), was purified to homogeneity with sulfated-dextran, DEAE-Sepharose, heparin-Sepharose and Sephadex G-150. HCII is a glycoprotein consisting of a single polypeptide chain with a Mr = 65,600 as determined by sedimentation equilibrium analysis.

Patients with congenital factor V deficiency have decreased factor Xa binding sites on their platelets.

Human platelets have binding sites for plasma coagulation Factor X(a) that are available only after the platelet release reaction. Platelets from 15 normal donors bound 216+/-52 (SD) molecules of Factor X(a) per platelet. The association of Factor X(a) with its platelet surface receptor results in a 300,000-fold increase in the catalytic activity of Factor X(a) in forming thrombin from prothrombin.