Binding of mercurials to membrane suspensions and undenatured proteins

Journal Article · Sun Jan 01 04:00:00 EST 1978 · Membrane Biochem.; (United States)

DOI:https://doi.org/10.3109/09687687809063861· OSTI ID:5128573

Berg, G G; Miles, E F

Binding capacities of membrane suspensions and dissolved compounds for mercurials were titrated by a new potentiometric method. Critical steps included a silver electrode of new design, the use of L-cysteine as a thiol buffer, a nitrogen atmosphere, and pretreatment of samples with equimolar mercurial and cysteine. Titrations had a sharp endpoint, accurate +-26 nmole methylmercury or +-8 nmole mercuric salt. Measurements of binding capacity of bovine serum albumin averaged 93% of the titer predicted for one SH group per molecule; those of human hemoglobin yielded 86 to 91% of the titer predicted for two SH groups per molecule. Yields dropped with exposure of protein solutions or membrane suspensions to atmospheric oxygen. Brain microsomes had significantly higher binding capacities (per milligram of protein) than red blood cell ghosts. The ratio of endpoint titers of CH/sub 3/HgCl to HgCl/sub 2/ averaged 2:1 in assays of cysteine, proteins, and membranes, showing that the assay was free of denaturation artifacts and protein-protein interference. Solutions of EDTA showed measurable binding of Hg/sup 2 +/ but not of Ch/sub 3/Hg/sup +/. Satisfactory titrations were also obtained with N-ethylmaleimide.

• Research Organization: Univ. of Rochester, NY
• OSTI ID: 5128573
• Journal Information: Membrane Biochem.; (United States), Journal Name: Membrane Biochem.; (United States) Vol. 2:1; ISSN MEBID
• Country of Publication: United States
• Language: English

Related Subjects

550200 -- Biochemistry
560300* -- Chemicals Metabolism & Toxicology
59 BASIC BIOLOGICAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ALBUMINS
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
BODY
BODY FLUIDS
BRAIN
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CELL MEMBRANES
CENTRAL NERVOUS SYSTEM
CHEMICAL ANALYSIS
CHEMICAL PREPARATION
CHLORIDES
CHLORINE COMPOUNDS
ELECTRODES
ERYTHROCYTES
GLOBIN
HALIDES
HALOGEN COMPOUNDS
HEMOGLOBIN
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
KINETICS
MATERIALS
MEMBRANES
MERCURY CHLORIDES
MERCURY COMPOUNDS
MERCURY HALIDES
METABOLISM
METHYLMERCURY
MICROSOMES
NERVOUS SYSTEM
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC MERCURY COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANOIDS
ORGANS
PIGMENTS
PORPHYRINS
POTENTIOMETRY
PROTEIN DENATURATION
PROTEINS
QUANTITATIVE CHEMICAL ANALYSIS
REACTION KINETICS
SYNTHESIS
TITRATION