Carboxylesterases (EC 3.1.1). Purification and Titration of Chicken, Sheep, and Horse Liver Carboxylesterases

Abstract

Chicken, sheep, and horse liver carboxylesterases have been purified by procedures involving ammonium sulfate fractionation, ion-exchange chromatography and gel filtration on Sephadex. The actual yields of the procedures described were as follows: chicken, 1 g from 2 kg of liver powder (chloroform-acetone); sheep, 200 mg from 400 g of powder (chloroform-acetone); horse, 230 mg from 800 g of powder (acetone). The purified enzymes are free of non-carboxyl-esterase protein as shown by gel electrophoresis, although they do contain electrophoretic variants. The equivalent weight of the chicken enzyme is 67,000 based on titration with p-nitrophenyl diethyl phosphate or bis(p-nitrophenyl) phosphate, whereas those of the sheep and horse enzymes are similar to 69,500 and similar to 70,000, respectively, based on titration with p-nitrophenyl dimethylcarbamate.

A thermoactive uropygial esterase from chicken: Purification, characterisation and synthesis of flavour esters

“…The enzyme exhibited one band corresponding to a molecular mass of about 50 kDa which corroborate with that of the turkey preduodenal esterase [13]. However, the molecular weight of CUE is lower than that of a carboxylesterase purified from the chicken liver (67 kDa) [20].…”

Horse carboxylesterases: Evidence for six CES1 and four families of CES genes on chromosome 3

“…Subsequent studies examined the kinetic properties of horse liver CES using a range of substrates and reported an equivalent weight of 70,000 for this enzyme based on titration with p -nitrophenyl dimethylcarbamate (Stoops et al 1975; Inkerman et al 1975). There are however no reports of amino acid sequences for horse liver CES or for other CES gene family members.…”

“…One of two ‘ion pairs’ that maintains the trimeric-hexameric subunit structures for human CES1 is retained by all horse CES1 subunits (78Lys/183Glu), whereas the second has been retained only for horse CES1.1, but has been lost as a result of a 186Arg →186Pro substitution for horse CES1.2-1.6 subunits, respectively. Given the reported oligomeric structure for horse liver CES (Inkerman et al 1975), it is likely that a subunit-subunit binding site has been maintained for the horse CES1-like subunits.…”

“…Even though horse liver CES was one of the first enzymes subjected to large scale purification (Burch, 1955) and has been biochemically characterized (Stoops et al 1975; Inkerman et al 1975), there are no previous reports of protein and genomic structures and sequences for horse CES for any of the mammalian CES classes. CES has been extensively investigated in other mammals and shown to serve a range of metabolic (Satoh & Hosokawa 2006; Redinbo & Potter 2005) and biomedical roles (Pindel et al, 1997; Xu et al, 2002; Imai, 2006; Mutch et al, 2007; Wang et al, 2007).…”

Carboxylesterases (EC 3.1.1). Amino Acid Composition of Liver Carboxylesterases

“…The various liver carboxylesterases were purified according to the procedures described as follows: ox, Runnegar et al (2); pig, Dudman and Zerner (3); chicken, sheep, and horse, Inkerman et al (1). The specific activities of the preparations are given in Table 1.…”