Characterization of the rat liver glucocorticoid receptor purified by DNA-cellulose and ligand affinity chromatography

Two rapid and high yield purification methods for the rat liver glucocorticoid receptor based on differential DNA affinity (method A) and ligand affinity (method B) chromatography are described. In method A, the amount of receptor in rat liver cytosol that can be activated and subsequently eluted from a DNA-cellulose column has been increased to 80% by introducing a second heat activation step. Using this method, 1.5 nmol of 25% pure glucocorticoid receptor can be routinely obtained per day from 15-20 rat livers. Method B yields about 2.2 nmol of 60% pure receptor with an overall yield of congruent to 60%. The quality of these purifications has been controlled by affinity labeling. In each case, more than 95% of purified binding activity represented the intact 92,000 +/- 400-Da glucocorticoid receptor polypeptide as shown by sodium dodecyl sulfate-gel electrophoresis and fluorography. No difference in the labeling pattern was observed using either [3H]triamcinolone acetonide (photoaffinity labeling) or [3H]dexamethasone 21-mesylate (electrophilic labeling). The electrophilic labeling step was performed in the cytosol prior to purification by method A to compare the labeled components thus purified with those obtained when the photoaffinity labeling was performed after the purification. Using this approach, distinct breakdown products of the glucocorticoid receptor were revealed, co-purifying during DNA affinity chromatography. Cross-linked receptor obtained by method A has been further purified to homogeneity by preparative sodium dodecyl sulfate-gel electrophoresis and successfully used as immunogen to raise glucocorticoid receptor antibodies in rabbits. These antibodies raised against glucocorticoid receptor, as well as those previously obtained using affinity chromatography-purified receptor, react with the receptor molecules irrespective of their method of purification. Glucocorticoid receptors purified by methods A and B have been analyzed for specific DNA-binding properties by the nitrocellulose filter binding assay.     

Recent Progress in the Purification of Adenosine Receptors

Abstract

A₁ adenosine receptors were purified to an apparent homogeneity from rat brain and testicular membranes by a novel affinity chromatography system using xanthine amine congener (XAC) as an immobilized ligand. This affinity chromatography was also useful for the purification of human brain A1 adenosine receptor.     

A BRAIN-SPECIFIC PROTEIN WITH AFFINITY FOR DNA1

Abstract— A procedure has been developed which allows the isolation from rat brain cytosol of a soluble acidic protein, designated DNA-110 protein, having two basic properties: selective affinity for single-stranded DNA and immunological specificity to the nervous system. Only two major purification steps, DNA-cellulose chromatography and affinity chromatography on immunoadsorbents are needed to give apparently pure protein. The purification steps of the DNA-110 protein have been followed by immunological assay. DNA-110 has a molecular weight of 68,000 and an isoelectric point of 5.9. It accounts for 1.95% of the total soluble protein and its concentration is 216 μg per g wet weight of rat brain. DNA-110 is immunologically unrelated to other soluble acidic brain-specific proteins and glycoproteins.     

Tyrosine aminotransferase from rat liver, a purification in three steps.

Tyrosine aminotransferase from rat liver was isolated by a three step purification method involving affinity chromatography, CM-50 chromatography and G-200 gel filtration. In order to synthesize the affinity gel, the coenzyme pyridoxamine-5′-phosphate was coupled via a spacer group to a sepharose matrix. The enzyme preparation showed a single band in SDS-acrylamide gel electrophoresis and contains three multiple enzyme forms. A molecular weight of 50,000 of the tyrosine aminotransferase subunit was estimated.     

PURIFICATION OF MYELIN CARBONIC ANHYDRASE

Abstract— A procedure has been developed for the purification of the membrane bound form of carbonic anhydrase from rat brain myelin. The procedure is rapid, requiring only two steps, and can be applied to small amounts of material. Conditions have been established whereby the enzyme can be almost quantitatively solubilized with up to a 60 fold increase in specific activity. Purification by affinity chromatography yields a preparation which is homogeneous by polyacrylamide gel electrophoresis. However, preliminary evidence suggests that activity may be reduced by the removal of lipids during chromatography and subsequent dialysis. The purified preparation is high in dicarboxylic and hydroxyl amino acids and contains only 1×2 cysteine residues. The reduction of cysteine appears to be essential for the full expression of enzymatic activity.     

Characterization of Adenylate Cyclase Purified from Rat Brain by Hydrophobic Chromatography

Abstract. Hydrophobic chromatography of detergent-solubilized rat brain adenylate cyclase on dodecyl-Sepharose produced a species that was soluble in the absence of detergent and could be manipulated like a conventional hydrophilic protein. Sevenfold purification was achieved by this technique. Further purification could then be effected by affinity chromatography on ATP-Sepharose. The purified enzyme was no longer sensitive to fluoride or guanyl nucleotides. No interaction of brain adenylate cyclase was observed with immobilized triazinyl dyes such as Cibacron Blue 3GA nor with concanavalin A-Sepharose. The molecular weight of the fluoride-activated catalytic complex in a freeze-dried membrane preparation was estimated to be 133,000 by irradiation inactivation.     

Nontransformed rabbit liver glucocorticoid receptor: purification, characterization and transformation

The molybdate-stabilized nontransformed form of the glucocorticoid receptor from rabbit liver has been purified approximately 8,000-fold by a three-step procedure. The first step involved protamine sulfate precipitation which allowed a 5-6-fold purification with 85% yield. The second step, affinity chromatography using a N-(12-dodecyl-amino) 9 alpha-fluoro-16 alpha-methyl-11 beta, 17 alpha-dihydroxy-3-oxo-1,4-androstadiene-17 beta-carboxamide substituted Sepharose gel, purified the receptor 1,500-2,000-fold as calculated by specific radioactivity. The third step involved high performance liquid chromatography resulting in overall purification near 8,000-fold. The final glucocorticoid receptor appeared about 60% pure. The purified nontransformed glucocorticoid receptor had a sedimentation coefficient of 9 S in 0.16 M phosphate containing 5-20% sucrose gradients and the Stokes radius was 6.1-6.3 nm as determined by low pressure gel filtration and HPLC. Binding specificity of the purified receptor was identical to that previously reported in crude rabbit liver cytosol. Isoelectricfocusing and ion-exchange chromatography showed that the purification procedure affected the net charge of the receptor protein. This phenomenon could be related to interactions between the glucocorticoid receptor and cytosolic factors. SDS polyacrylamide gel electrophoresis showed a major Mr = 94,000 protein band which is in good agreement with previously reported values for glucocorticoid receptors. Transformation of the purified receptor was achieved after removal of molybdate by exposure at 25 degrees C to 0.4 M KCl. Characterization of the molecular forms was performed by means of incorporation into isolated nuclei, affinity towards polyanionic exchangers and high pressure size exclusion chromatography. Results show that about 40% of the receptor is in the transformed state.     

Biochemical characterization including amino acid and carbohydrate compositions of canine and human brain Thy-1 antigen.

Human and canine brain Thy-1 antigens were solubilized in deoxycholate and antigen activity was followed both by conventional absorbed anti-brain xenosera of proven specificity and by mouse monoclonal antibodies to canine and human Thy-1. It is shown that greater than 80% of Thy-1 activity in the dog and man binds to lentil lectin, that the mobility on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis of canine and human Thy-1 is identical with that of rat Thy-1 and that the Stokes radius in deoxycholate of canine and human brain Thy-1 is 3.0 nm and 3.25 nm respectively. Both lentil lectin affinity chromatography followed by gel-filtration chromatography on the one hand and monoclonal antibody affinity chromatography on the other gave high degrees of purification of the brain Thy-1 molecule in the dog and man, resulting in single bands staining for both protein and carbohydrate on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis (except for a slight contaminant of higher molecular weight staining for protein but not carbohydrate with human Thy-1 purified by lentil lectin and gel-filtration chromatography). Analysis of canine and human brain Thy-1 purified by monoclonal antibody affinity chromatography with additional gel filtration through Sephadex G-200 showed that these molecules had respectively 38% and 36% carbohydrate. The amino acid and carbohydrate compositions were similar to those previously reported for Thy-1 of the rat and mouse, the main point of interest being the presence in canine and human brain Thy-1 of N-acetylgalactosamine, which has been reported in rat and mouse brain Thy-1 but not in Thy-1 from other tissues.     

Purification of B-50 by 2-mercaptoethanol extraction from rat brain synaptosomal plasma membranes

Several methods have been described previously for the purification of the nervous-tissue specific protein kinase C substrate B-50 (GAP-43). In this paper we present a new purification method for B-50 from rat brain which employs 2-mercaptoethanol to release the protein from isolated synaptosomal plasma membranes. Most likely, 2-mercaptoethanol reduces disulfide bonds involved in the linkage of B-50 to the membrane. After washing the membranes with 100 mM NaCl to detach loosely bound proteins, B-50 is the major protein (and the only protein kinase C substrate) released by 0.5% 2-mercaptoethanol treatment. Further purification to apparent homogeneity is achieved by affinity chromatography on calmodulin sepharose. B-50 binds to calmodulin in the absence of calcium and specifically elutes from the column with 3 mM calcium. The procedures described is simple, rapid and highly suitable for large scale purification of B-50 from rat brain.     

Purification of L-glutamate decarboxylase by affinity chromatography

L-Glutamate decarboxylase (L-glutamate 1-carboxy-lyase, EC 4.1.1.15) from rat brain synaptosomal extract was partially purified by affinity chromatography. On further purification by DEAE-Sephadex A 50 and Sephadex G-200, L-glutamate decarboxylase was purified to greater extent. It was found that a single affinity chromatography by appropriate elution gave a highly purified protein giving a single band of high specific activity on polyacrylamide gradient gel slab electrophoresis with minimal contamination. Substrate specificity of the purified enzyme was modified in the presence of 6-azauracil or phenylalanine resulting in decreased specificity to L-glutamate and increased specificity to L-aspartate.     

PURIFICATION OF RAT BRAIN CHOLINE ACETYLTRANSFERASE1

Abstract— The purification of choline acetyltransferase (ChAc) has been hampered by the increasing instability of the enzyme in the course of purification. By working with a high concentration of protein and by adding glycerol to the enzyme, the stability was increased. The purification was performed by centrifuging twice, at low and high salt concentrations, precipitation by ammonium sulphate and chromatography on carboxymethyl–Sephadex, hydroxylapatite and Sephadex G 100. The final steps were performed by using chromatography on an immunoabsorbent; this consists of agarose-coupled gammaglobulins of antisera devoid of any activity against ChAc itself and directed against other proteins still present in the purest ChAc preparation achieved by conventional biochemical techniques. The purest rat brain ChAc preparation had a specific activity of 20 μmol/min/mg of protein after a 30,000-fold purification. The enzyme was not homogeneous in polyacrylamide gel electrophoresis performed either at pH 4.5 or with sodium dodecyl sulphate. Pure ChAc from rat brain would have a specific activity of approximately 100 μmol/min/mg of protein.     

Purification of skeletal muscle hexokinase by affinity elution chromatography

Type II hexokinase (EC 2.7.1.1) has been purified from rat skeletal muscle by a simple procedure involving chromatography on DEAE-cellulose, affinity elution chromatography from phosphocellulose, and gel filtration on Sephadex G-200. The key to the preparation of homogeneous enzyme is the affinity elution step in which an effector molecule, glucose 6-phosphate, is used as the eluting ligand. A 5300-fold purification is obtained by the procedure and over 400-fold purification is obtained in the affinity elution step alone. Approximately 3.3 mg of homogeneous hexokinase with a specific activity of 120 units/mg is obtained from 800 g of rat limb.     

OCCURRENCE OF A SEROTONIN SULPHOTRANSFERASE IN THE BRAIN

Abstract— —An enzyme catalysing the transfer of sulphate from 3'-phosphoadenylsulphate to serotonin was purified from rabbit brain. The purification procedure involved ammonium sulphate fractionation of the 200,000 g supernatant of rabbit brain homogenate, treatment with alumina Cγ, and chromatography on DEAE-cellulose. The enzyme was purified 67-fold from the 200,000 g supernatant of the brain homogenate. The intracranial distribution of the sulphotransferase was investigated and the cerebellum found to have rather high activity. The sulphotransferase activities of rabbit, dog, rat and bovine brains were compared; rabbit brain had the highest activity, followed by dog, rat and bovine brain.     

Characterization and immunocytochemical demonstration of glucocorticoid receptor using antisera specific to transformed receptor

Cytosolic and nuclear forms of the glucocorticoid receptor were characterized using immunochemical techniques. Antibodies were raised in rabbits to an M_r 58,000 fragment of the transformed (DNA-binding) glucocorticoid receptor purified from rat liver cytosol by DNA-cellulose chromatography and polyacrylamide gel electrophoresis. Antibodies reacted with the transformed receptor form in a radioimmunoassay for glucocorticoid receptor. Western blot analysis of antibody reactivity revealed a single M_r 185,000 receptor form in rat liver cytosol but a smaller M_r 85,000 form in nucleosol, indicating the M_r 85,000 form is the transformed receptor. Furthermore, western blot analysis indicates that the M_r 185,000 receptor undergoes proteolysis during receptor purification and in vitro transformation processes by generating immunochemically similar proteins of smaller molecular weights. An identical M_r 185,000 glucocorticoid receptor was detected in cytosols of four rat tissues; liver, brain, adrenal medulla, and thymus. The glucocorticoid receptor was localized to the cytoplasm and nucleus of rat adrenal medulla cells by immunohistochemistry, demonstrating the existence in vivo of the transformed receptor and translocation of the receptor from cytoplasm to nucleus.     

Protein purification using a soluble affinity matrix: purification of estrogen receptor with estradiol-polylysine conjugate.

A new strategy for protein purification using a soluble affinity matrix is described. The method was used for purification of estrogen receptor. Cytosols from rat uteri and human fibroid uterine tissue, after fractionation by ammonium sulfate, were treated with estradiol-polylysine conjugate. The highly basic affinity complex was separated from other proteins by DEAE-Sephacel chromatography. After dissociation of the eluted complex with excess estradiol, the receptor was recovered by CM-Sephadex chromatography. A 2000-fold purification of the rat uterine estrogen receptor was obtained with an activity recovery of 35%.     

Purification of the glucocorticoid receptor from rat liver cytosol.

The [3H]-triamcinolone acetonide-labeled glucocorticoid receptor from rat liver cytosol was purified to 85% homogeneity according to sodium dodecyl sulfate gel electrophoresis. It consisted of one subunit with a molecular weight of 89,000 and had one ligand-binding site per molecule. The purification involved sequential chromatography on phosphocellulose, DNA-cellulose twice, and Sephadex G-200. Between the two chromatography steps on DNA-cellulose, the receptor was heat activated. The receptor was affinity eluted from the second DNA-cellulose column with pyrodixal 5'-phosphate. The purification achieved in the first three chromatographic steps varied between 60 and 95% homogeneity in different experiments. After chromatography on the second DNA-cellulose column, the steroid.receptor complex had a Stokes radius of 6.0 nm and a sedimentation coefficient of 3.4 S in 0.15 M KCl. In the absence of KCl, the sedimentation coefficient was 3.6 S. After concentration on hydroxylapatite, the steroid.receptor complex was analyzed by isoelectric focusing in polyacrylamide gel. The radioactivity was shown to focus together with the major protein band with pI 5.8. Following limited proteolysis with trypsin, the radioactivity, together with the major protein band, focused at pI 6.2 as previously described for the unpurified steroid.receptor complex.     

THE PURIFICATION AND PROPERTIES OF PIG BRAIN CATECHOL-o-METHYLTRANSFERASE

Abstract— The previously reported affinity chromatography technique (G ulliver & T ipton , 1978 b ) has been adapted for the large-scale purification of pig brain catechol- o -methyltransfcrase. The enzyme prepared by this method is apparently homogeneous by polyacrylamide gel electrophoresis criteria and is stable for prolonged periods of storage at—5°C in 20% (v/v) glycerol. Kinetic measurements, molecular weight criteria and antiserum reaction suggest that the brain and liver forms of catechol- o -methyltransferase are very closely related, if not identical.     

Steroid-affinity purification of the rat liver glucocorticoid hormone receptor complex

The molybdate-stabilized GHRC was isolated from rat liver cytosol with a 9000-fold purification and 46% yield. The major purification step was achieved using an affinity matrix consisting of an agarose support coupled to a dexamethasone ligand via an aliphatic spacer arm. Spacer arms containing disulfide bridges were found to be unsuitable due to their instability in cytosol. To reduce the non-specific binding properties of the affinity matrix, underivatized amino groups were acetylated, since the receptor was found to bind avidly to such groups thus evading elution by the ligand. Sodium molybdate present during biospecific elution from the gel stabilized the steroid-binding activity of the receptor. The use of denaturing and sulfhydryl modifying reagents (NaSCN, DMSO, Mersalyl) during elution led to partial or complete irreversible loss of steroid-binding activity of the unoccupied receptor. Efficient biospecific elution occurred at competing concentration of high affinity steroid in the presence of sodium molybdate. The ligand specific eluate was further purified by DEAE-Sephacel chromatography resulting in additional purification of 3.2-fold. The GHRC eluted from the DEAE-Sephacel column at a salt concentration characteristic of the untransformed GHRC. Molybdate was removed from the purified untransformed GHRC in the ligand eluate by DEAE-Sephacel chromatography in the absence of molybdate, for subsequent heat transformation.     

Purification of rat hepatic glucokinase

We have developed a rapid, reliable procedure for the purification of rat hepatic glucokinase. The purification utilizes DEAE-cellulose, two affinity chromatography steps, and high-performance liquid chromatography. Glucokinase with a specific activity of 240 units/mg, a 42 K-fold purification, and a yield of 60% is obtained. The enzyme appears as a homogeneous band, with over 99% purity as assessed by polyacrylamide gel electrophoresis. The purification procedure can be completed in 5 days.     

大鼠CRIP2蛋白的表达和分离纯化

目的:获得大鼠crip2基因片段,并在大肠杆菌中表达、纯化大鼠CRIP2(cysteine-rich intestinal protein 2)蛋白。方法:从大鼠主动脉组织中提取总DNA,RT-PCR扩增出相应大小的crip2 DNA片段,与pGEM-T-easy载体连接后测序;将测序正确的crip2按照BamHⅠ和HindⅢ酶切位点克隆入原核表达载体pRSET A,将连接产物转化大肠杆菌BL21,挑出阳性克隆,IPTG诱导表达重组的6×His融合蛋白,通过镍柱进行纯化。结果:PCR获得的crip2序列与GenBank报道的一致(为707 bp);重组融合蛋白在大肠杆菌BL21中以可溶形式高效表达,经SDS-PAGE和Western印迹分析,在相对分子质量为27×103处有特异的蛋白条带,经镍柱纯化后,得到了高纯度的CRIP2融合蛋白。结论:克隆了大鼠crip2基因片段,并在大肠杆菌BL21中高效表达,亲和层析纯化后获得高纯度的CRIP2融合蛋白。