Characterisation of the citrate synthase reaction with propionyl-CoA.

Experiments with propionyl-CoA stereoselectively deuteriated in the propionyl moiety demonstrate that the formation of (2S,3S)-methylcitric acid (1) catalysed by citrate (si)-synthase occurs with inversion of configuration in the propionyl moiety; the absolute configurations of the methylcitric acids 1 and 2 indicate a si attack on oxaloacetate. Deuterium in the pro-S position is exchanged for protium 60 times faster than deuterium in the pro-R position. Experiments with (R,S)-(2-2H1)propionyl-CoA allowed the determination of isotope effects. For the enzymatic formation of 1, a primary deuterium isotope effect kH/kD = 1.8 and a secondary alpha-deuterium isotope effect kH/kD = 0.99 were calculated; both are effects on Vmax/KM.

Glycosidases from the interferon producing lymphoid cell line Namalva and from three other lymphoid cell lines.

1. The occurrence of lysozyme, neuraminidase and fourteen other glycosidases was investigated in the three lymphoma cell lines Namalva, Raji and Daudi derived from a Burkitt's lymphoma and the lymphoblastoid cell line Robinson from Epstein-Barr virus transformed normal peripheral blood lymphocytes. High activity of beta-N-acetyl-D-glucosaminidase was found in three of the cell lines, which also showed fairly high activities of beta-N-acetyl-D-galactosaminidase, alpha-D-mannosidase and beta-D-mannosidase. In Daudi the highest glycosidase activity was found for beta-D-mannosidase. 2. Neuraminidase and lysozyme were not detected in any of the four cell lines. 3. These cell lines showed characteristic enzyme patterns and enzyme ratios which may be used for the identification of the cell lines. 4. When calculated on a protein basis no statistically significant change in glycosidase activities of the cells could be recorded during interferon production.

NCA: a differentiation antigen of myelopoietic cells in humans and hominoid monkeys.

NCA, a normal colonic and granulocytic antigen, could be demonstrated in serum and in myelopoietic, but not lymphopoietic or erythropoietic, cells of Homo sapiens and other Primates. The levels of NCA in both serum and myelopoietic cells of Homo and hominoids were higher than those of more distant relatives of the same order. Thus, the classic phylogenetic differences are reflected also by the distribution of NCA. Hyperimmunization of Macaca irus, in which the NCA content of serum and cells is low, led to occurrence of anti-NCA IgG in all animals. The phylogenetic differences may accordingly have to do with slight antigenic NCA differences between Homo and other Primates rather than differences in amount only. Purified NCA did not affect growth and maturation of myelopoietic stem cells in vitro, whereas anti-NCA inhibited development of the majority of myelopoietic clusters and colonies.