Kidney esterases of Mus musculus: further polymorphism of esterase-6, esterase-9, and a new esterase, esterase-20

Detection of activity and mass spectrometric identification of mouse liver carboxylesterase and aldehyde dehydrogenase separated by non-denaturing two-dimensional electrophoresis after extraction with detergents

To examine the activities and identity of enzymes associated with organelles such as microsomes and mitochondria, proteins from mouse liver were extracted using the non-ionic detergents Nonidet P-40 (NP-40), polyoxyethylene sorbitan monooleate (Tween 80), polyoxyethylene isooctylphenyl ester (Triton X), n-octyl beta-D-glucoside (octyl glycoside) or anionic detergent sodium dodecylsulfate (SDS) after the removal of cytosolic proteins. The proteins extracted by detergents were separated by non-denaturing two-dimensional electrophoresis (2-DE). The activities of esterase and aldehyde dehydrogenase were retained by non-denaturing 2-DE after treatment with each non-ionic detergent, but the activities were reduced or lost when the proteins were extracted with more than 0.5% SDS. For proteomic analysis of the organelle-associated proteins in mouse liver, proteins were separated by non-denaturing 2-DE and were identified using electrospray ionization tandem mass spectrometry (ESI-MS/MS) after the proteins were solubilized by octyl glycoside, NP-40 and 0.1% SDS. Several organelle-associated proteins such as carboxylesterase, aldehyde dehydrogenase, glucose regulated protein and HSP60 were identified. These results indicate that the activities and identity of detergent-soluble enzymes can be examined by this non-denaturing 2-DE and mass spectrometry.

Genetic characterization of esterase 28 (ES-28) of the house mouse

The genetics of esterase-28, the major esterase of cauda epididymidis of the house mouse, has been studied after separation by polyacrylamide gel electrophoresis and isoelectric focusing. Four phenotypes are distinguished. Segregation of Es-28 in two backcross series indicated linkage to Es-1, Es-9, and Es-22. The Es-28 locus was placed into esterase cluster 1 on chromosome 8.

cDNA cloning of esterase 1, the major esterase activity in mouse plasma

We report here the cloning of a partial cDNA for Esterase 1, the major esterase activity in mouse plasma. A 470 base pair insert was isolated from a lambda gt11 cDNA library constructed from mouse liver poly A+ RNA, and identified by hybrid selected translation. We show that the sexual dimorphism displayed in the plasma levels of this protein is caused by a difference at the level of transcription. In addition, RFLP data using mouse recombinant inbred strains mapped this clone at the Es-1 locus on mouse chromosome 8.

Esterase alleles of inbred mouse strains maintained in The Netherlands

Fifty-seven mouse strains were examined for genetic variation at 21 esterase loci. Three new alleles were found:Es-6din strain A/WySna,Es-llein FTC/CpbU andEs-18cin two WLL/BrA sublines. At most loci there was a single allele found in over 80% of strains, with one or two rare alleles. However, theEs-1, 3, 10, 13, 25and27loci were much more polymorphic. Although several loci were linked on chomosomes 3, 8 and 9, linkage disequilibrium was only found betweenEs-5andEs-11(chromosome 8) andEs-26andEs-27(chromosome 3). There was also significant disequilibrium betweenEs-1and3, Es-1and10, andEs-3and10, which are on different chromosomes, suggesting that the 57 strains are not a random sample of inbred mouse strains. Fifty-four strains were closely related, with theEs-7b, –17a, –18a, –23cset of alleles, which are typical ofMus musculus domesticus. The three exceptional strains were MOL3 (Mus musculus molossinus), WLL/BrA (English–Norwegian origin) and TA2 (Chinese origin). There were 10 groups of strains which were identical at all loci. Sublines of the same strain were usually identical. Sometimes more distantly related strains, such as CBA/Bi, C3H/He, SM and DBA/Li, were identical, and in a few cases strains with no known common ancestry such as C58 and MAS were identical. Attempts to discriminate between a subset of 22 American and 15 European strains were unsuccessful, suggesting that the European strains add only in a quantitative manner to the gene pool of ‘laboratory mice’, whereas wild-derived strains such as MOL3 are genetically quite distinct from other laboratory mice.

Genetic polymorphism of esterase B3 in human leukocytes

Human tissues contain an esterase activity called ESB3, detectable by starch gel electrophoresis followed by staining with alpha-naphthyl butyrate. Using mononuclear leukocytes, we demonstrated an electrophoretic variant of ESB3. Family studies suggest that the variant is inherited as a simple Mendelian trait; individuals with the ESB3 2-1 phenotype are heterozygotes, designated ESB3(1)ESB3(2), to distinguish them from the more common homozygotes, ESB3(1)ESB3(1). The frequency of the ESB3(2) allele is estimated to be 0.035 in U.S. Whites. No homozygotes for this allele have yet been found. Our studies suggest that the enzyme from ESB3 1 individuals exists primarily as a trimer of three identical subunits with a molecular weight of approximately 58,000 daltons. The genetic variant (ESB3(2) allele) appears to be the result of a mutation that does not affect the charge of the subunit, but rather reduces its ability to form and maintain the trimeric structure.

Identity of esterase-22 and egasyn, the protein which complexes with microsomal beta-glucuronidase

Recent experiments have demonstrated that egasyn not only sequesters beta-glucuronidase in microsomes by forming high molecular weight complexes with beta-glucuronidase, but also has carboxyl esterase activity. We have found several new phenotypes of egasyn-esterase after electrophoresis and isoelectric focusing of liver homogenates and purified egasyn of inbred and wild mouse strains. Several phenotypes corresponded in relative mobility and relative isoelectric point among inbred strains to that recently reported for esterase-22 by Eisenhardt and von Deimling [(1982). Comp. Biochem. Physiol. 73B:719]. This genetic evidence, plus a wide variety of comparative biochemical and physiological data, indicates that egasyn is identical to esterase-22. Both parental types of egasyn isozymes are expressed in heterozygous F1 progeny, suggesting that alterations in the egasyn structural gene are responsible for the altered isoelectric points. Also, egasyn is a monomer since no new esterase bands appear in F1 progeny. The variants in isoelectric point of egasyn map at or near the egasyn (Eg) gene within the esterases of cluster 1 near Es-9 on chromosome 8.

Nonspecific esterases of mammalian testis. Comparative studies on the mouse (Mus musculus) and rat (rattus norvegicus)

Ten different nonspecific esterases in both mouse (Mus musculus) and rat (Rattus norvegicus) testis were identified following the analysis of electrophoretic patterns using genetic, developmental, and biochemical criteria. None of the enzymes were unique to testis, although the pattern of activity was testis specific. The enzymes comprised, in each species, six carboxylesterases (EC 3.1.1.1), one arylesterase (EC 3.1.1.2), one acetylesterase (EC 3.1.1.6), and two butyrylesterases (tentative designation). Cholinesterase (EC 3.1.1.8) was not detected. Individual homology relationships were recognized between the two species for all of these activities, except three of the carboxylesterases; however, these were coded for by homologous gene clusters. Similarities between the two species extended to the developmental course of expression and the modulation of the pattern of activity by the testicular feminization (Tfm) mutation. We describe the effects of the sex reversal (Sxr) mutation in the mouse, as well as the distribution of individual activities between Leydig cells and seminiferous tubules. The results of earlier histochemical studies are interpreted in the light of the present investigation. The correspondence between mouse- and rat-testis esterases suggests that the results could serve as a basis for mammalian testis esterase systems in general.

Identification and development of a genetically closely-linked carboxylesterase family of the mouse liver

Six carboxylesterase isozymes (viz. ES-1, ES-6, ES-9, ES-20, ES-22 and ES-24), governed by esterase gene cluster 1 on chromosome 8 of the house mouse, were identified electrophoretically in liver supernatants using their biochemical, genetic and developmental characteristics. ES-1 and ES-20 were expressed as liver-specific forms. The peri- and postnatal development of the six isozymes indicated that they were individually regulated at the genetic level, although the isozymes were regulated as a group when compared to genetically unrelated esterases. The concept of evolutionary divergence following repeated gene duplication of an ancestral esterase structural gene was extended to cover divergence of the temporal (regulatory) genes associated with the multigene family. Allelic variation of the temporal genes was more limited than that of the corresponding structural genes.

Esterase-23 (ES-23): characterization of a new carboxylesterase isozyme (EC 3.1.1.1) of the house mouse, genetically linked to ES-2 on chromosome 8

Genetic variation of a carboxylesterase isozyme (EC 3.1.1.1) of the house mouse, designated ES-23, is described. ES-23 was found in kidney, liver, and intestine. The isozyme was resistant to inhibition by 10(-3) mol/liter eserine and was stained using alpha-naphthyl butyrate or 5-bromoindoxyl acetate as substrate. Five different phenotypes, ES-23A to ES-23E, could be distinguished by disc electrophoresis and by isoelectric focusing. ES-23 is controlled by a structural locus situated within the esterase gene cluster 2 on chromosome 8. An analysis of allele distribution among different strains suggested a separate structural locus for the isozyme, Es-23e, which is closely linked to the loci Es-2, Es-5, Es-7, and Es-11. Of the five phenotypes, only ES-23B was expressed in lung. This variation is apparently controlled by a cis-acting regulatory element, presumably a temporal locus, Es-23t, closely linked to the presumed structural locus Es-23e.

Heterogeneity of Es-1 esterases in the rabbit (Oryctolagus cuniculus)

Analysis of the Es-1 system in the rabbit with polyacrylamide gel electrophoresis (PAGE) revealed a high degree of individual variation. In the liver the number of esterase bands found in the Es-1 region of the gels ranged from 2 to 16. The results indicate that one locus with three alleles is responsible for all of the esterase bands in the Es-1 region. The most plausible explanation for the observed heterogeneity is that each of the alleles codes for a protein (MW 65,000 +/- 2000) that is changed by posttranslational modifications, thus giving rise to two to five monomeric enzymes with esterase activity. Polymerization of these monomers then results in 1-11 dimers. Based on similarities with mouse Es-9, chromosomal homology between rabbit Es-1 and mouse Es-9 is proposed.

The non-specific esterases of mouse lung

The non-specific esterases of the lung of the house mouse, M. musculus, were examined by polyacrylamide electrophoresis and by isoelectric focusing. At least 13 different esterases were distinguished and identified, mainly by their catalytic properties, susceptibility to inhibition, developmental patterns and phenotypic variation amongst different strains. A list of diagnostic features of the 13 esterases was presented. None of the esterases was lung-specific. However, the pattern of esterases found in the adult lung was characteristic of that organ. It was pointed out that this pattern is associated with the high degree of tissue differentiation in the adult lung. At least 8 esterases were found which belong to the isozyme system of carboxylesterase EC 3.1.1.1, under the control of genes located on chromosome 8. These esterases accounted for about 90% of the esterase activity in the lung.

Organ specific expression of esterase-6 in the house mouse, Mus musculus

Esterase-6 in fresh homogenates of heart muscle and testis of the house mouse shows a two band (C allele) or three band (A allele) pattern in disc electrophoresis. These primary bands generated in series of secondary bands upon lowering the pH of the homogenates, and the secondary pattern, possibly resulting from partial proteolysis, was seen in varying degrees in fresh homogenates from a range of organs. Interrelationships between the primary and secondary bands were demonstrated by isoelectric focusing. The esterase-6 content of twenty different organ homogenates was estimated from electrophoretic gels, and a high level of this enzyme was observed in those organs most actively involved in fat metabolism. The possible participation of esterase-6 in fatty acid utilization is discussed. Similarities between esterase-6 of the house mouse and esterase-4 of the rat were demonstrated, further strengthening the view that these enzymes are homologous.

Purification and characterization of esterase 6A, a trimeric esterase of the house mouse (Mus musculus)

Esterase 6A was isolated from mouse lung and purified 440-fold by ion-exchange chromatography, inverse ammonium sulphate gradient solubilization, gel filtration and isoelectric focusing. The resultant product was apparently homogenous by the criteria of polyacrylamide gel electrophoresis and immunodiffusion, and consisted of the electrophoretic form 6A3. A single species of subunit was present on sodium dodecyl sulphate gel electrophoresis. The molecular weight of the native protein was found to be about 178,000 with a subunit molecular weight of about 60,000. The equivalent weight obtained by active-site titration with diethyl-p-nitrophenyl phosphate was approximately 178,000 g/mol, indicating a functional asymmetry in the trimer. The enzyme was shown to have a high affinity for 4-nitrophenyl hexanoate (Michaelis constant Km = 4.4 mumol/l) with a relatively low catalytic efficiency (catalytic constant kcat = 12 s-1). Esterase 6A was immunologically related to esterase 1 and esterase 9, with which it is genetically closely linked. Further properties of the three esterases were compared.

Interstrain variation of esterase-22, a new isozyme of the house mouse

1. A new liver esterase in the house mouse, ES-22, is described, using different staining methods after dose electrophoretic separation on polyacrylamide gels. 2. Five different phenotypes, ES-22A to ES-22E, could be distinguished in various mouse strains. ES-22 is genetically closely linked to ES-6, ES-9 and ES-20 on chromosome 8, but its distribution among different strains appears to be independent from these isozymes. 3. ES-22 is clearly different from other chromosome 8-controlled esterases, with respect to its organ expression and its catalytic properties. 4. A gene locus Es-22 with five alleles is suggested. 5. It is proposed that the genes coding for the carboxylesterase isozyme system on chromosome 8 constitute a multigene family as defined by Hood et al. (1975).