The amino acid composition is different between the cytoplasmic and extracellular sides in membrane proteins.

The amino acid composition of transmembrane proteins was analyzed for their three separate portions: the transmembrane apolar, cytoplasmic and extracellular regions. The composition was different between cytoplasmic and extracellular peptides: alanine and arginine residues were preferentially sited on the cytoplasmic side, while the threonine and cysteine/cystine were preferentially sited on the extracellular side. The composition of cytoplasmic and extracellular peptides of membrane proteins corresponded to those of intracellular and extracellular types of soluble proteins, respectively. This difference in composition was independent of the peptide orientation against the membrane. Peptide chains could be correctly assigned as either cytoplasmic or extracellular, solely from an analysis of sequence composition. For single-spanning membrane proteins the predictive accuracy was 90%, whereas for multi-spanning proteins this was 85%.     

Effect of capsular polysaccharide of Klebsiella pneumoniae on host resistance to bacterial infections. I. Induction of increased susceptibility to infections in mice.

When Klebsiella pneumoniae capsular polysaccharide (CPS-K) from type 1, Kasuya strain, was injected intraperitoneally (i.p.) immediately before i.p. bacterial challenge, the survival time of mice infected with Salmonella enteritidis NUB 1 (virulent strain) was shortened and the mortality rate for mice infected with S. enteritidis NUB 31 (avirulent strain) was enhanced. The promotion of infection with S. enteritidis NUB 1 by CPS-K depended upon its dose, the effect of CPS-K being demonstrable up to as little as 0.2 mug per mouse. In the case of S. enteritidis NUB 31, the effect of CPS-K was detectable only when more than 20 mug per mouse was injected. As a result of enumeration of bacterial populations in the peritoneal washing, blood, liver and spleen, it was revealed that CPS-K promoted in vivo growth of S. enteritidis NUB 1 and NUB 31. In addition, CPS-K enhanced the mortality rate in mice infected with Streptococcus pyogenes or Streptococcus pneumoniae. The peak CPS-K effect on infection with S. enteritidis NUB 1 was seen when given immediately before bacterial challenge. The active substance responsible for the infection-promoting effect of CPS-K was neutral CPS-K, which is distinct from the O antigen and from acidic CPS-K (the type-specific capsular antigen). Preparations of neutral CPS-K isolated from the other three strains of K. pneumoniae exhibited a marked infection-promoting effect comparable with that of preparations from the Kasuya strain. Neutral CPS-K, with identical antigenicity to that from the Kasuya strain, has already been found to exert a strong adjuvant effect on antibody responses to various antigens in mice. No parallelism exists between infection-promoting activity and adjuvant activity of neutral CPS-K.     

Microbial adjuvant and autoimmunity. IV. The induction of thyroid lesions in syngeneic X-irradiated mice by the transfer of spleen cells from mice immunized with thyroid extract and Klebsiella O3 lipopolysaccharide

The role of humoral and cellular immune responses in the initiation and maintenance of autoimmune thyroiditis was investigated in mice immunized with syngeneic thyroid extract and Klebsiella O3 lipopolysaccharide (KO3 LPS) as an adjuvant. The transfer of spleen cells from hyperimmunized mice to 400R-irradiated syngeneic mice produced definite lesions in the thyroid glands, whereas the transfer of immune sera failed to do so. No lesions were induced in normal intact mice by the same transfer of sera and spleen cells from hyperimmunized mice. It was suggested that the induction of thyroiditis by immunization using KO3 LPS adjuvant is primarily due to cell-mediated immunity and that pretreatment of mice by X-irradiation is essential for production of the lesions. The role of X-irradiation in the induction of thyroiditis was discussed.     

Physalins E and H,new physalins from Physalis angulata and P. lancifolia

From the stems and leaves of Physalis angulata and P. lancifolia, the isolation of five new physalins E, F, G, H and I is reported. The structures of physalins E and H are established respectively as 5,6-dihydro-5α,7α-dihydroxy and 7β-hydroxy derivatives of physalin B.     

Picosecond fluorescence lifetime of the coenzyme of D-amino acid oxidase

Conformational difference surrounding the coenzyme, FAD, of D-amino acid oxidase (D-amino-acid:O2 oxidoreductase (deaminating), EC 1.4.3.3) between its monomeric and dimeric forms were examined by observing fluorescence of FAD. The fluorescence lifetimes of the coenzyme was measured directly with a mode-locked Nd:YAG laser and a streak camera in picosecond region. The values of lifetime of FAD fluorescence in the monomer and dimer were 130 +/- 20 ps and 40 +/- 10 ps, respectively. The relative quantum yield of the fluorescence of FAD combined with the protein to that of free FAD depended on the concentration of the enzyme; it was higher at lower concentration. Comparing the lifetime with relative quantum yield of FAD combined with the protein, it is concluded that the fluorescence is quenched mostly by a dynamic process. These results indicate that the distance between the isoalloxazine nucleus and a quencher is nearer in the dimer than in the monomer.