Fatty acid binding

About: Fatty acid binding is a research topic. Over the lifetime, 730 publications have been published within this topic receiving 35980 citations.

Half-life of serum elimination of perfluorooctanesulfonate,perfluorohexanesulfonate, and perfluorooctanoate in retired fluorochemical production workers.

Abstract: Perfluorooctanesulfonate [PFOS; CF3(CF2)7SO3−] and its acid salts were derived from perfluorooctanesulfonyl fluoride [POSF; CF3(CF2)7SO2F]. Major product applications were developed using POSF through formation of N-alkylsulfonamides that were used in surfactants, paper and packaging treatments, and surface protectants (e.g., carpet, upholstery, textiles). Depending on the specific functional derivitization or polymerization, these POSF-based products may have degraded or metabolized, to an undetermined degree, to PFOS, a stable and persistent end product that has a widespread presence in the general population (Butenhoff et al. 2006) and wildlife (Houde et al. 2006). Salts of perfluorooctanoic acid, in particular ammonium perfluorooctanoate (APFO), have been used as surfactants and processing aids in the production of fluoropolymers and fluoro-elastomers. Industrial production of the salts of perfluorooctanoic acid occur through electrochemical fluorination and telomerization. Perfluorooctanoate [PFOA; CF3(CF2)6COO−], the dissociated carboxylate anion, has been measured in humans worldwide but generally at lower nanogram per milliliter concentrations than PFOS (Houde et al. 2006). In rats, PFOS and PFOA are not metabolized and enter into the enterohepatic circulation (Johnson et al. 1984; Kemper 2003; Kuslikis et al. 1992; Vanden Heuvel et al. 1991). Because of the stability of the carbon–fluorine bond and the high electronegativity of perfluorinated alkyl acids, metabolism would not be favored; thus, perfluorohexanesulfonate (PFHS) is also not expected to be metabolized. Based on the determination of volumes of distribution from single-dose intravenous studies in cynomolgus monkeys, the distributions of PFOS, PFHS, and PFOA are primarily extracellular (Butenhoff et al. 2004; Noker and Gorman 2003a, 2003b). Kerstner-Wood et al. (2003) found PFOS, PFHS, and PFOA to be highly bound in rat, monkey, and human plasma over a concentration range of 1–500 μg/mL. When incubated with human plasma protein fractions, all three compounds were highly bound (99.7 to > 99.9%) to albumin, and showed affinity for β-lipoproteins (95.6, 64.1, and 39.6% for PFOS, PFHS, and PFOA, respectively). Some binding to α - and γ -globulin fractions and minor interactions with transferrin (PFHS and PFOA) were also noted. PFOS and PFOA have been shown to compete for fatty acid binding sites on liver fatty acid binding protein, with PFOS giving the stronger response (Luebker et al. 2002). The elimination rates of PFOS and PFHS have been studied in male and female cynomolgus monkeys after intravenous dosing (Noker and Gorman 2003a, 2003b) and for PFOS after repeated oral dosing (Seacat et al. 2002). Noker and Gorman (2003a, 2003b) reported mean (± SD) terminal elimination half-lives, ranging from 88 to 146 days (132 ± 13 days for males and 110 ± 26 days for females) for PFOS and 49 to 200 days (141 ± 52 days for males and 87 ± 47 days for females) for PFHS, after intravenous dosing of three male and three female cynomolgus monkeys in separate experiments, with no significant difference between males and females or between the two compounds. Seacat et al. (2002) reported an approximate terminal elimination half-life of 200 days for PFOS in male and female cynomolgus monkeys during 1 year immediately following 6 months of daily oral dosing with either 0.15 or 0.75 mg/kg PFOS. Elimination rates in species other than the monkey have been determined for PFOS and PFOA. Within 89 days after a single intravenous dose of 14C-PFOS, 30% of the 14C was excreted in the urine and 12% in the feces of male rats (Johnson et al. 1979). For PFOA, significant interspecies differences have been observed (Hundley et al. 2006; Kudo and Kawashima 2003), and differential expression of organic anion transporters in renal proximal tubule cells have been suggested as an explanation for sex differences in the rat (Kudo et al. 2002) and low elimination rates in humans (Andersen et al. 2006). The purpose of the present study was to estimate the serum elimination half-life of PFOS, PFHS, and PFOA in humans through the long-term follow-up of retired fluoro-chemical production workers. Although these retirees were no longer occupationally exposed, their serum concentrations were expected to be considerably higher than those of the general population.

Crystal structure of human serum albumin complexed with fatty acid reveals an asymmetric distribution of binding sites

Abstract: Human serum albumin (HSA) is the most abundant protein in the circulatory system. Its principal function is to transport fatty acids, but it is also capable of binding a great variety of metabolites and drugs. Despite intensive efforts, the detailed structural basis of fatty acid binding to HSA has remained elusive. We have now determined the crystal structure of HSA complexed with five molecules of myristate at 2.5 A resolution. The fatty acid molecules bind in long, hydrophobic pockets capped by polar side chains, many of which are basic. These pockets are distributed asymmetrically throughout the HSA molecule, despite its symmetrical repeating domain structure.