ABSTRACT
Bacteriorhodopsin (bR) is the light-driven proton pump found in the purple membrane of Halobacterium salinarium. A series of conformational changes occur during the bR photocycle which involve alterations in buried-helical structure as well as in the protonation state of Asp residues which are part of the proton transport pathway. Here we report evidence that similar conformational changes occur upon removal of the retinylidene chromophore of bacteriorhodopsin to form the apoprotein bacterioopsin (bO). This suggests a simple ligand-binding model of proton transport in bacteriorhodopsin which may have relevance to other transport and signal transducing membrane proteins including the visual photoreceptor rhodopsin.
Subject(s)
Bacteriorhodopsins/chemistry , Bacteriorhodopsins/metabolism , Proton Pumps/metabolism , Bacteriorhodopsins/radiation effects , Halobacterium/metabolism , Halobacterium/radiation effects , Ion Transport/radiation effects , Ligands , Light , Models, Molecular , Molecular Structure , Protein Conformation/radiation effects , Proton Pumps/radiation effects , Signal Transduction , Spectroscopy, Fourier Transform InfraredSubject(s)
Learning , Memory , Retention, Psychology , Classification , Humans , Models, PsychologicalABSTRACT
An account is given of some human diseases which affect one sex more than the other. An age-sex realtionship has been noted among British patients with acquired toxoplasmic lymphadenopathy. This is compared with the findings of other European workers. A possible explanation is offered taking all these diseases into consideration together with some of the experimental work done in animals and some of the variations in immunological responses by man.
Subject(s)
Lymph Nodes/parasitology , Lymphatic Diseases/parasitology , Morbidity , Toxoplasmosis/epidemiology , Adolescent , Adult , Age Factors , Antibodies/analysis , Child , Child, Preschool , Europe , Female , Humans , Infant , Infant, Newborn , Lymphatic Diseases/epidemiology , Lymphatic Diseases/immunology , Male , Middle Aged , Sex Factors , Toxoplasma/immunology , Toxoplasmosis/immunology , United KingdomABSTRACT
A comparison of the indirect haemagglutination test (IHAT) with the dye test (DT) in 23 infants with congenital toxoplasmosis showed that in the early part of the first year of life the IHAT titres were nearly all lower than the DT titres. In six cases the IHAT was negative or the titre was so low that the cases could have been missed in routine screening. Later in the first year the IHAT titres became higher than the DT and remained so. The infants belonging to mothers with a high IHAT and therefore assumed to have become infected early in pregnancy had severe infections which included all the cases of hydrocephalus. Infants of mothers with low IHAT titres relative to the DT and therefore thought to have been infected later in pregnancy had generalized, mild or subclinical infection. With some difficulty a suitable commercial conjugated anti-IgM serum was found that gave positive results in immunofluorescent antibody tests for specific IgM antibody with all the infected infants and their mothers throughout the first year and negative results in uninfected infants and their mothers.
Subject(s)
Coloring Agents , Hemagglutination Tests , Toxoplasmosis, Congenital/diagnosis , Age Factors , Antibodies, Anti-Idiotypic , False Negative Reactions , Female , Fluorescent Antibody Technique , Hemagglutination Tests/methods , Humans , Immunoglobulin M/analysis , Infant , Infant, Newborn , PregnancyABSTRACT
Three types of antibody curve have been demonstrated by testing sera during the course of acquired toxoplasmosis by six different techniques. These three types are due to cell-wall antibody, (demonstrated by four of the techniques), to antibody to soluble antigen, and to IgM antibody to the cell wall. These findings have been supported by absorption experiments. A scheme is presented for testing single sera by two or three different tests to indicate the stage and duration of the infection.
