Chromatography of amino acids, indoles and imidazoles on thin layers of avicel and cellulose and on paper

Smith, I.R.; Rider, Linda J.; Lerner, Richard P.

doi:10.1016/s0021-9673(01)98902-2

Cited by 30 publications

(1 citation statement)

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“…I4C(U)-Labeled L-amino acids (sp act, 227-495 pCi/pmol) and [rneth~xy-~H]inulin (466 pCi/mg) were purchased from New England Nuclear (Boston, MA, U.S.A.), whereas [N-methyl-'H]diazepam was obtained from Amersham-Searle (Arlington Heights, IL, U.S.A.). The radiochemical purity of each I4C-amino acid was established as >98% with TLC (Smith et al, 1967). ['HI-Inulin was purified prior to use by gel chromatography on Sephadex G-25.…”

Section: Methodsmentioning

confidence: 99%

Kinetics of Neutral Amino Acid Transport Across the Blood‐Brain Barrier

Smith¹,

Momma²,

Aoyagi³

et al. 1987

Journal of Neurochemistry

425

327

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Neutral amino acid (NAA) transport across the blood-brain barrier was examined in pentobarbital-anesthetized rats with an in situ brain perfusion technique. Fourteen of 16 plasma NAAs showed measurable affinity for the cerebrovascular NAA transport system. Values of the transport constants (Vmax, Km, KD) were determined for seven large NAAs from saturation studies, whereas Km values for five small NAAs were estimated from inhibition studies. These data, together with our previous work, provide a complete set of constants for prediction of NAA influx from plasma. Among the NAAs, Vmax varied at least fivefold and Km varied approximately 700 fold. The apparent affinity (1/Km) of each NAA was related linearly (r = 0.910) to the octanol/water partition coefficient, a measure of NAA side-chain hydrophobicity. Predicted influx values from transport constants and average plasma concentrations agree well with values measured using plasma perfusate. These results provide accurate new estimates of the kinetic constants that determine NAA transport across the blood-brain barrier. Furthermore, they suggest that affinity of a L-alpha-amino acid for the transport system is determined primarily by side-chain hydrophobicity.

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Section: Methodsmentioning

confidence: 99%