Hereditary Spherocytosis (hs) Due To Loss of Anion-exchange Transporter

Background. Hereditary spherocytosis encopasses a heterogenous group of inherited disorders due to alteration of r.b.c. surface/volume ratio. Spectrin deficiency is the most common observed defect. We analyzed a case of HS associated with band 3 deficiency without spectrin reduction. Methods. In the study of a family originating from southern Italy, we show that a 20% deficiency of band 3 with normal spectrin content may be responsible for dominantly inherited hereditary spherocytosis (HS). The proband is a 12 years old girl consulting for jaundice, chronic anaemia and splenomegaly. Her mother had a similar haematologic phenotype. Results. Electrophoretic analysis of erythrocyte membrane proteins showed a deficiency in band 3 protein. Band 3 protein chymotryptic fragments, deglycosylated band 3, and its isolated cytoplasmic domain, all displayed normal electrophoretic migrations. Furthermore, the tryptic peptides profile of the cytoplasmic domain of the protein did not demonstrate any abnormality, nor did the amino acid composition of the peptides. Analysis of the membrane proteins during erythrocyte ageing, evaluated in density-fractionated red cells, showed that band 3 content was normal in the lighter fraction, whereas in the denser fraction band 3 deficiency was more pronounced than in membranes from non fractionated red blood cells. Conclusions. This case describes HS due to anion exchange transporter deficiency. Our results on fractioned red cells support the hypothesis that the defect was probably due to a band 3 protein loss during cell ageing and not to a primitive quantitative defect

Comparing the Polarities of the Amino Acids: Side-Chain Distribution Coefficients between the Vapor Phase, Cyclohexane, 1 -0ctano1, and Neutral Aqueous Solutiont

ABSTRACT: To obtain an indication of the tendencies of amino acids to leave water and enter a truly nonpolar condensed phase, distribution coefficients between dilute solution in water and dilute solution in wet cyclohexane have been determined for each of the common amino acid side chains at p H 7; they are found to be closely related to the inside-outside distributions of the side chains observed in globular proteins. There was no evidence that excess water enters cyclohexane in association with these solutes. Cyclohexane-to-water distribution coefficients can be combined with vapor-to-water distribution coefficients reported earlier to yield vapor-to-cyclohexane distribution coefficients. Vapor-to-cyclohexane distribution coefficients provide an experimental index of susceptibility to attraction by dispersion forces, and the corresponding free energies are found to be linearly related to side-chain surface areas. Observations using different solvents and variously substituted side chains suggest that alcohols such as 1-octanol exert a specific attraction on the side chain of tryptophan. When less polar phases are used as a reference, leucine, isoleucine, valine, phenylalanine, and methionine are found to be more hydrophobic than tryptophan. w h e n "molecular recognition" events occur in aaueou