[The decrease of circulating serum hemopexins in non-hemolytic diseases].

Human embryos have been biopsied at either the cleavage or the blastocyst stage of development. One to two blastomeres were removed from cleavage-stage embryos and 2-6 cells from blastocysts. The biopsy specimens were subjected to gene amplification by the polymerase chain reaction (PCR) and a comparison made of amplification efficiencies of two unique target sequences, one located within the beta-globin gene and containing the sickle-cell locus and the other a polymorphic dinucleotide repeat. When the cleavage-stage biopsy sample consisted of an intact blastomere with a clearly discernible nucleus, an amplification efficiency of 89% was achieved for each target locus. This was similar to that achieved with cleavage-stage biopsy samples consisting of two blastomeres or with blastocyst biopsy samples consisting of 2-3 trophectoderm cells. When biopsy samples consisted of four or more trophectoderm cells, both target loci were amplified in all samples tested. When the biopsy sample was heterozygous at the dinucleotide repeat locus and the biopsy consisted of one or more intact cells with a clearly discernible nucleus, both alleles were amplified in > 80% of biopsy samples. When four or more trophectoderm cells were used for the PCR, both alleles were amplified in all heterozygous samples. Target sequences were never amplified from biopsy samples which lysed prior to transfer into the reaction tube. Analysis of DNA fragments amplified from the dinucleotide repeat locus indicated that in most cases faithful amplification of biopsy DNA template had taken place.(ABSTRACT TRUNCATED AT 250 WORDS)

Beta-Globulins↗

PubMed1993

Interaction of myo-inositol hexaphosphate (MIHP) with beta-globulin from Sesamum indicum L. Kinetics and thermodynamics.

beta-Globulin, the low molecular weight protein fraction from Sesamum indicum L., interacts with myo-inositol hexaphosphate (MIHP) maximally at pH 3.0, with concomitant precipitation up to 85 +/- 2% at an MIHP concentration of 8 x 10(-4) M. The kinetics of interaction as followed by stopped-flow spectrophotometry suggested the reaction to be of pseudo first-order, having an initial fast step followed by a relatively slow step of rate constants 1.9 x 10(-2) s-1 and 1.2 x 10(-3) s-1, respectively at 1 x 10(-4) M MIHP concentration. The analysis of the complex indicated the presence of polymer as seen in sedimentation velocity experiment. This was accompanied by conformational change of a three-fold decrease in beta-structure and also an increase in fluorescence emission intensity accompanied with a red shift from 330 to 334 nm. Stoichiometric analysis of MIHP binding suggested four independent binding sites for MIHP, with a free energy change, delta G zero = 5.1 kcal mol-1 resulting from a binding constant of 3.6 x 10(3) M-1.

Beta-Globulins↗

PubMed1992

Association of proteins in acidic solutions--a case study with beta-globulin.

The investigation of the effect of acid pH on the structure of beta-globulin indicated several transitions as a function of pH. Upon reducing the pH from 7.0, the beta-globulin molecule underwent an expansion due to hydration up to pH 5.0, and a further increase in H+ concentration resulted in unfolding. This is a single step cooperative denaturation as indicated by the viscosity profile. At extreme acid pH values (below pH 2.0) the protein associates or folds to a different conformational motif as shown by blue shift of ultraviolet fluorescence emission maximum and decrease in reduced viscosity values by more than 30% due to an entropically driven hydrophobic interaction. The conformational analysis of beta-globulin showed a decrease up to pH 3.0, followed by an increase in the ordered structure at low pH values indicating that the low pH values stabilized this new conformation. These results are discussed in view of the molten globule structure of proteins.

Beta-Globulins↗