1. The M and N blood group substances were treated with different amino-group reagents, such as : acetic-, succinic-, and phthalic-anhydrides, benzyloxycarbonylchloride, dinitrofluorobenzene, nitrous acid and 0-methyl-isourea.2. It was shown that these reagents blocked or destroyed 2-4 free amino groups (mainly lysine E-NH, groups) per one subunit of M or N blood group substance of mol. wt. 30,000. No other effects were found under the conditions used.3. The blocking or decomposition of amino groups, connected with the loss of their positive charge, lowered the blood group activity of M and N mucoids and did not decrease their activity towards phytoagglutinins and the inhibitory activity of viral hemagglutination. The guanidylation of amino groups did not destroy the blood group activity of M and N mucoids.The M and N blood group substances from human erythrocytes have been known as the sialoglycoproteins [l]. They exhibit three types of serological activity : (a) the specific blood group activity towards anti-M and anti-N rabbit immune sera; (b) the less specific activity towards anti-M and anti-N phytoagglutinins; (c) the inhibitory activity of hemagglutination by influenza viruses. The activities (a) and (c) were lost when terminally situated N-acetylneuraminic acid (NANA) was set free by neuraminidase or by mild acid hydrolysis [2,3], but activity towards phytoagglutinins was even increased after removal of NANA [4,5]. I n this paper the evidence is presented for the specific role of free amino groups, especially of free 8-NH, groups of lysine residues, in the blood group activity of M and N blood group substances. MATERIALS AND METHODSThe M, N, and MN blood group mucoids were obtained from human erythrocytes of blood group OM, ON, or OMN respectively, by phenol extraction of ghosts [I].Acetic-, succinic-, and phthalic-acid anhydrides, benzyloxycarbonylchloride and dinitrofluorobenzene were commercially available products. 0-methylisourea was a gift of dr. K. Nowak from the Dept. Enzyme. Neuraminidase (EC 3.2.1 .IS).Neuraminidase from Vibrio cholerae was the product of Behringwerke.Anti-M and anti-N rabbit immune sera were supplied by the State Laboratory of Sera and Vaccines (Warsaw). The extract from the seeds of Vicia granzinea, containing anti-N phytoagglutinins, was prepared according to van Wageningen and Nijenhuis IS]. The M and N blood group activity and the N , activity, (activity towards V . graminea anti-N phytoagglutinins), were determined by an inhibition of hemagglutination : the various dilutions of the studied preparation were incubated for 30 minutes a t a room temperature with equal volumes of anti-serum or V . graminea extract, followed by the addition of double volumes of 2 O/ , , erythrocyte suspension; the degree of agglutination was recorded after 30 minutes. The activity was expressed as the minimal concentration (mglml) of the blood group substance, giving the complete inhibition of serum or V . graminea extract of the titre 1/8-1/16. Influenza virus Lee was obtained from the Dept. o...

No abstract

No abstract

I .The purification and crystallization of 2-phospho-~-glycerate hydro-lyase from human skeletal muscle is described.2 . Preparations of the crystalline enzyme were found to be homogenous as examined in free boundary and gel electrophoresis. Chromatography on Sephadex G 75 and TEAE-cellulose revealed only one component.3. The sedimentation constant was found to be 5.9 x see, the diffusion constant 5.6 x 10-7 cmZ/sec and the intrinsic viscosity 4.10 ml/g. The molecular weight calculated from these data was found to be 95,000 f 3,000, and the frictional ratio 1.26. 4. The properties of the enzyme are compared with those of phosphopyruvate hydratase from rabbit muscle and yeast.