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Zn2+‐dependent 3H‐leucine transport across lobster intestine uses a peptide transporter
Author(s) -
Ahearn Gregory A.,
Obi Ijeoma,
Wells Anna L.
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.1065.2
Subject(s) - leucine , homarus , zinc , transporter , amino acid , chemistry , flux (metallurgy) , biochemistry , peptide , biophysics , biology , organic chemistry , crustacean , gene , ecology
An in vitro intestinal perfusion apparatus was used to characterize mucosal to serosoal (MS) and serosal to mucosal (SM) Zn2+‐dependent 3H‐L‐leucine transport by intestine of the lobster, Homarus americanus. Transmural 20 μM MS 3H‐L‐leucine fluxes across lobster intestine were a hyperbolic function of luminal zinc concentration ((1 to 50 μM) following Michaelis‐Menten kinetics (Km = 2.67 ± 0.74 μM; Jmax = 19.56 ± 2.22 pmol/cm2 x min). Transmural 20 μM SM 3H‐L‐leucine fluxes were not affected by serosal zinc, resulting in a highly significant stimulation of net amino acid transfer to the blood by luminal metal. MS fluxes of 20 μM 3H‐L‐leucine were also hyperbolic functions of luminal [Na+] and [H+]. MS flux of 3H‐L‐leucine was a sigmoidal function of luminal [L‐leucine] and was stimulated by 20 μM luminal zinc at both pH 7.0 and 5.5. The greatest enhancement of amino acid transport occurred at the lower pH. MS flux of 20 μM 3H‐L‐leucine in the presence of 20 μM zinc was significantly inhibited by addition of 100 μM luminal glycylsarcosine, and MS flux of 20 μM 3H‐glycylsarcosine was inhibited by 100 μM L‐leucine in the presence of 20 μM zinc. Results suggest that 3H‐L‐leucine and zinc form a complex (Leu‐Zn‐Leu] in solution that may use a peptide transporter during MS fluxes. Supported by NSF grant IBN 04‐21986 and USDA grant 2010‐65206‐20617.