Selective crystallization of horse isoferritins

Various precipitating agents were examined in order to crystallize horse heart and spleen ferritins. Cadmium sulfate induced the crystallization of the spleen ferritin, while 2-methyl-2,4-pentanediol and poly(ethylene glycol) only induced that of the heart ferritin. Isoelectric focusing analysis showed that the crystals grown from cadmium sulfate contained only the more acidic isoferritins, and those grown from methyl pentanediol only the less acidic isoferritins. Heart ferritin crystallizes in a cubic space group, as previously reported for spleen ferritin crystals grown from cadmium sulfate.

Transient removal of proflavine inhibition of bovine beta-trypsin by the bovine basic pancreatic trypsin inhibitor (Kunitz). A case for "chronosteric effects"

The formation of the bovine beta-trypsin-bovine basic pancreatic trypsin inhibitor (Kunitz) (BPTI) complex was monitored, making use of three different signals: proflavine displacement, optical density changes in the ultraviolet region, and the loss of the catalytic activity. The rates of the reactions indicated by the three different signals were similar at neutral pH, but diverged at low pH. At pH 3.50, proflavine displacement precedes the optical density changes in the ultraviolet and the loss of enzyme activity by several orders of magnitude in time (Antonini, E., Ascenzi, P., Menegatti, E., and Guarneri, M. (1983) Biopolymers 22, 363-375). These data indicated that the bovine beta-trypsin-BPTI complex formation is a multistage process and led to the prediction that, at pH 3.50, BPTI addition to the bovine beta-trypsin-proflavine complex would remove proflavine inhibition and the enzyme would recover transiently its catalytic activity before being irreversibly inhibited by completion of BPTI binding. The kinetic evidences, by completion of BPTI binding. The kinetic evidences, here shown, verified this prediction, indicating that during the bovine beta-trypsin-BPTI complex formation one transient intermediate occurs, which is not able to bind proflavine but may bind and hydrolyze the substrate. Thus, the observed peculiar catalytic behavior is in line with the proposed reaction mechanism for the bovine beta-trypsin-BPTI complex formation, which postulates a sequence of distinct polar and apolar interactions at the contact area.

Apparent subunit heterogeneity of NAD-dependent glyceraldehyde-3-phosphate dehydrogenase from spinach leaves

NAD dependent glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.1.12) from spinach leaves has been previously investigated: the enzyme, homogeneous on conventional chromatography and analytical disc electrophoresis, shows on denaturing condition, non identical subunits of 37,000 and 14,000 daltons which have been separated in equimolar amounts after sodium dodecyl sulphate treatment (Speranza and Gozzer, 1978). Affinity chromatography carried out on these enyzme preparations allowed to separate a fully active enzyme of 150,000 daltons M.W. from a protein of 70,000 daltons M.W. which is devoid of glyceraldehyde-3-phosphate dehydrogenase activity: the purified enzyme shows 37,000 daltons subunits, while the second protein is made up of 14,000 daltons subunits. It is also reported that the 70,000 daltons protein could be separated from the enzyme by selective crystallization in the presence of organic solvents. It is concluded that the NAD-dependent glyceraldehyde-3-phosphate dehydrogenase from spinach leaves, as the homologous enzyme from other sources, is a tetramer of 37,000 daltons subunits.

Crystallographic studies on D-amino acid oxidase

D-amino acid oxidase, a flavoprotein from hog kidneys, has been crystalized in two different forms. Orthorhombic prisms have been obtained from the enzyme.benzoate complex at pH 8.3; the space group is C2221 and the cell dimensions are a = 325A, b = 138.8 A, c = 200 A. At lower pH values, the enzyme crystallizes in trigonal prisms with a = b = 116.0 A, c = 399 A, space group P3112 or its enantiomorph. The two crystal forms have been obtained at 28 degrees C while at 4 degrees C only weak evidence of crystallization has been detected. In both crystalline modifications, the protein is highly associated.

Duration and complications of multiple pregnancies

Multiple pregnancies reach full term only in a remarkably lower percentage with respect to single pregnancies. Even in the case of multiparae, delivery occurs some three weeks before term. Complications may concern either pregnancy and puerperium or delivery. The former include (1) abortions, especially frequent in the case of monoplacental and monochorial pregnancies; (2) rarer events, such as hydramnios, placenta praevia, association of an ectopic pregnancy with an intrauterine pregnancy, molar degeneration of one egg with normal development of the other; (3) gestoses of the first and second trimester, more frequent than in single pregnancy; and (4) higher incidence, during puerperium, of hemorrhage, phlebitis, and uterine subinvolution. With respect to delivery, normal delivery only occurs in approximately 70% of twin pregnancies, the period of dilatation being generally longer than normal. Better assistance and techniques during labor and especially in the interval between delivery of first and second twin have remarkably reduced the higher mortality rate, especially for the second twin.

Twinning and blood groups. I. ABO frequencies in twins and controls: immunological considerations

Several studies have appeared in the literature to support the hypothesis of a differential incidence of twin births according to the antigenic structure of maternal erythrocytes (Gedda, 1961).

Osborne and DeGeorge (1957) wrote that twin births exhibit a higher incidence when mothers belong to group O, as compared to other groups within the ABO system; a similarly increased incidence of twin births was indicated for rh-negative mothers within the Rh-Hr system.

The availability of a large number of immunohematological data concerning twin pairs and nontwin individuals examined in our Institute have encouraged us to verify whether this material could reveal some a posteriori effect of the selective tendencies that have been related to the parental level.

Limiting our study in this phase to the ABO system, we have collected data on 1190 twin individuals and 1454 nontwin individuals, for all of whom the ABO blood group had been recorded.

The first step in our analysis was the perequation of the nontwin distribution to the twin distribution, obtaining the figures reported in the column “controls” in Tab. I.