Filter-Probe Extractor: A Tool for the Rapid Determination of Oil-Water Partition Coefficients

1982 ◽  
Vol 71 (5) ◽  
pp. 602-604 ◽  
Author(s):  
E. Tomlinson
Keyword(s):  
Partition Coefficients ◽  
Rapid Determination ◽  
Oil Water

scholarly journals Evidence for two asymmetric conformational states in the human erythrocyte sugar-transport system

1975 ◽  
Vol 145 (3) ◽  
pp. 417-429 ◽  
Author(s):  
J E Barnett ◽  
G D Holman ◽  
R A Chalkley ◽  
K A Munday
Keyword(s):  
Glucose Transport ◽  
Transport System ◽  
Human Erythrocyte ◽  
Partition Coefficients ◽  
External Medium ◽  
Sugar Transport ◽  
Conformational States ◽  
Glucose Transport System ◽  
Oil Water

6-O-methyl-, 6-O-propyl-, 6-O-pentyl- and 6-O-benzyl-D-galactose, and 6-O-methyl-, 6-O-propyl- and 6-O-pentyl-D-glucose inhibit the glucose-transport system of the human erythrocyte when added to the external medium. Penetration of 6-O-methyl-D-galactose is inhibited by D-glucose, suggesting that it is transported by the glucose-transport system, but the longer-chain 6-O-alkyl-D-galactoses penetrate by a slower D-glucose-insensitive route at rates proportional to their olive oil/water partition coefficients. 6-O-n-Propyl-D-glucose and 6-O-n-propyl-D-galactose do not significantly inhibit L-sorbose entry or D-glucose exit when present only on the inside of the cells whereas propyl-beta-D-glucopyranoside, which also penetrates the membrane slowly by a glucose-insensitive route, only inhibits L-sorbose entry or D-glucose exit when present inside the cells, and not when on the outside. The 6-O-alkyl-D-galactoses, like the other nontransported C-4 and C-6 derivatives, maltose and 4,6-O-ethylidene-D-glucose, protect against fluorodinitrobenzene inactivation, whereas propyl beta-D-glucopyranoside stimulates the inactivation. Of the transported sugars tested, those modified at C-1, C-2 and C-3 enhance fluorodinitrobenzene inactivation, where those modified at C-4 and C-6 do not, but are inert or protect against inactivation. An asymmetric mechanism is proposed with two conformational states in which the sugar binds to the transport system so that C-4 and C-6 are in contact with the solvent on the outside and C-1 is in contact with the solvent on the inside of the cell. It is suggested that fluorodinitrobenzene reacts with the form of the transport system that binds sugars at the inner side of the membrane. An Appendix describes the theoretical basis of the experimental methods used for the determination of kinetic constants for non-permeating inhibitors.

Chromatographic Determination of Rubber in Plant Latexes

1956 ◽  
Vol 29 (3) ◽  
pp. 1026-1033 ◽  
Author(s):  
Dorado E. Bernal
Keyword(s):  
Partition Coefficients ◽  
Chromatographic Method ◽  
Rapid Determination ◽  
Chromatographic Determination ◽  
Partition Chromatography ◽  
Biological Cycle

Abstract Partition chromatography on paper makes possible the separation of rubber hydrocarbon from latex. This method offers a means which is both simple and rapid for determining the presence of rubber in plant latexes and for the subsequent estimation of its percentage in a given latex. The method also gives a fraction which is composed of the nonrubber components. In addition to this, the method makes possible a comparison of the partition coefficients of rubber hydrocarbon isolated from latexes of different plants. Experiments are now in progress, the purpose of which is the application of the chromatographic method to the rapid determination of plant rubbers. By its simplicity, this method unquestionably has certain advantages in the identification of rubber in any particular flora and in studies of this hydrocarbon in its various phases of the biological cycle of the plant.

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