The dimerization reactions of complete Bence-Jones protein Au (VC-Au) and of its variable fragment (V-Au) were compared in 0.2 M (ionic strength) sodium phosphate buffer, pH 6.8 at 20 degrees C. The dimerization constant for VC-Au (6.6 X 10(4) M-1) was slightly smaller than a previously published value for the fragment (1.1 X 10(5) M-1). The reaction enthalpies were positive for both processes. Temperature jump experiments exhibited two kinetic phases. The relaxation time of the fast phase as well as its concentration dependence and amplitude were almost identical for VC-Au and V-Au. Only small differences were observed in the slow phase. These close similarities between the reactions of the two proteins demonstrate that dimerization occurs mainly via interactions between the variable domains and that the constant domains interfere very little. From the observation of two relaxation times it follows that the dimerization mechanism for both VC-Au and A-Au must include at least three reacting species. Mechanisms with an isomerization between monomers in two conformational states and a single dimer species are excluded by the data. Alternative mechanisms with a single monomeric species but isomerization between dimers give a rather unsatisfactory fit. A good fit can be obtained if it is assumed that both monomers and dimers can exist in two states. Rate constants of the association and dissociation steps are of the order of 10(7) M-1 s-1 and 10(2) s-1. Isomerization rate constants are in the range of 10 s-1.

Bence Jones Protein↗

PubMed1978

Transapical aortic perfusion with a double-barreled cannula.

The transapical aortic perfusion method is a new approach to cardipulmonary bypass and is performed with an infusion cannula placed in the ascending aorta through the left ventricular apex. The technique is applicable to almost all varieties of open-heart surgery, and is the most efficient method in infants and small children. A double-barreled forked cannula performs the two functions of aortic infusion and left ventricular decompression. With a Bakelite obturator, its cannulation to the aorta is very quick and easy. The transapical aortic perfusion method with a double-barreled cannula has been utilized in 156 open-heart operations with 17 perioperative fatalities and 1 late death. The 138 surviving patients have done well for periods up to four years. The perfusion method was developed from the left heart bypass and assisted circulation technique independently invented by Chardack's group and by us in 1966 and 1969, respectively.

Adolescent↗

PubMed1978

Mutagenic action of triose reductone and ascorbic acid on Salmonella typhimurium AT 100 strain.

Explore the source record for details and available documents.

Ascorbic Acid↗

PubMed1978

Isolation and characterization of a new antitumor polysaccharide, KS-2, extracted from culture mycelia of Lentinus edodes.

A new antitumor and antiviral substance, KS-2, was prepared by ethanol precipitation of the hot water extract of culture mycelia of Lentinus edodes KSLE 007. It was further purified by ECTEOLA-cellulose and Sephadex G-100 column chromatography based on the interferon-inducing activity. Its homogeneity was revealed by CsCl density gradient centrifugation, electrophoresis on cellulose acetate and Sephadex G-100 and ECTEOLA-cellulose column chromatography. KS-2 is mainly composed of alpha-linked mannose and contains a small amount of peptide which consists of serine, threonine and alanine with residual amounts of the other amino acids. The estimated molecular weight of KS-2 is between 6.0 X 10(4) and 9.5 X 10(4). KS-2 suppressed the growth of EHRLICH as well as Sarcoma-180 tumors in mice when given either orally or intraperitoneally. It is also capable of inducing an interferon in mice when dosed orally or intraperitoneally. The acute LD50 of KS-2 was found to be extremely low, more than 12,500 mg/kg when administered orally to mice.

Agaricales↗

PubMed1978

Evaluation of succinyl neocarzinostatin in vivo.

The toxicity of the bis-succinyl derivative of the protein antibiotic, neocarzinostatin, was compared with the parent compound, neocarzinostatin (NCS), in rats. The derivative was found to be about two to five fold more active than NCS in vivo. The antitumor activity in rats bearing eleven distinct Yoshida hepatoma ascitic cell lines was tested under four possible combinations with regard to sites of drug and tumor cell administration. The results indicate that the antitumor spectrum of the derivative had changed slightly. Antitumor activity in mice was also tested with L1210 and P388 lymphatic leukemia, and with B16 melanocarcinoma. When the effect of the derivative was compared with parental NCS at the molecular level with respect to the inhibition of DNA synthesis in vitro, the specific activities of the two were found to be almost identical. These results were interpreted to indicate that the succinyl derivative of NCS was more stable to inactivation and proteolytic break-down in vivo than NCS as observed previously in in vitro studies.

Animals↗