Dicyclohexylcarbodiimide (DCCD) sensitive organic cation/H/sup +/ antiporter in renal brush border membrane vesicles (BBMV)

Conference · Sat Mar 01 00:00:00 EST 1986 · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)

OSTI ID:5463013

Sokol, P P; Holohan, P D; Ross, C R

We tested the hypothesis that organic cation transport in BBMV is coupled to the countertransport of a H/sup +/ by employing a prototypic organic cation, N/sup 1/-methylnicotinamide (NMN), and a rapid filtration assay. Two H/sup +/ gradient uncouplers, carbonyl cyanide m-chlorophenylhydrazone (CCCP)/sub 3/ and gramicidin D were effective in dissipating H/sup +/ driven (/sup 3/H)NMN transport. Nigericin, a K/sup +//H/sup +/ exchanger, generated a H/sup +/ gradient in situ which drove the net accumulation of NMN. The molecular mechanism of H/sup +/ coupling was examined employing DCCD, a hydrophobic carbodiimide, which inactivates essential carboxylate groups, the putative H/sup +/ receptor. DCCD inactivated NMN transport irreversibly with an IC/sub 50/ of 2.6..mu..M whereas the hydrophilic carbodiimide, 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide, did not. DCCD inactivation followed pseudo-first-order kinetics and was not affected by NMN. A double logarithmic plot of the apparent rate constants vs. (DCCD) gave a slope of 0.8. The data are consistent with a simple bimolecular reaction mechanism and imply that one molecule of DCCD inactivates one carboxylate group per active transport unit. The results show that (1) the transport of organic cations is coupled to the countermovement of a H/sup +/ and (2) a carboxylate group is essential for H/sup +/ binding and translocation.

• Research Organization: SUNY Upstate Medical Center, Syracuse
• OSTI ID: 5463013
• Report Number(s): CONF-8604222-; TRN: 86-028355
• Journal Information: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Vol. 45:3; Conference: 70. annual meeting of the Federation of American Society for Experimental Biology, St. Louis, MO, USA, 13 Apr 1986
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
HYDROGEN COMPOUNDS
BIOCHEMICAL REACTION KINETICS
NICOTINAMIDE
MEMBRANE TRANSPORT
CATIONS
CELL MEMBRANES
FILTRATION
IMIDES
KIDNEYS
MOLECULAR BIOLOGY
TRACER TECHNIQUES
TRITIUM COMPOUNDS
AMIDES
AZINES
BODY
CELL CONSTITUENTS
CHARGED PARTICLES
HETEROCYCLIC COMPOUNDS
IONS
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
MEMBRANES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
PYRIDINES
REACTION KINETICS
SEPARATION PROCESSES
VITAMIN B GROUP
VITAMINS
550201* - Biochemistry- Tracer Techniques