Purification of kinases by general ligand affinity chromatography

Application of kinetic-based biospecific affinity chromatographic systems to ATP-dependent enzymes: studies with yeast hexokinase

This study is concerned with the development of kinetic-based bioaffinity chromatographic systems for purification of ATP-dependent kinases, with a particular focus on the allosteric yeast hexokinase enzyme (EC 2.7.1.1). Synthesis and characterization of highly substituted N(6)-linked and S(6)-linked immobilized ATP derivatives are described using a rapid solid-phase modular approach. Evaluation of the new immobilized ATP derivatives has been carried out using model chromatographic studies with yeast hexokinase, employing specific substrate analogues (N-acetyl-D-glucosamine and suramin) to promote biospecific adsorption, in the presence and absence of citrate (a so-called allosteric activator of hexokinase activity). In this paper, successful bioaffinity chromatography systems were developed for yeast hexokinase and, as a result, interesting binding and catalytic properties of the enzyme were highlighted and explored. The overall results confirm the potential for extrapolation of the kinetic locking-on tactic, a general kinetic-based bioaffinity approach already developed for the NAD(P)(+)-dependent dehydrogenases, to ATP/ADP-dependent enzymes. However, in view of the enhancement of the intrinsic ATPase activity of hexokinase with glucosamine derivatives, and the coincidental hydrolysis of immobilized ATP to immobilized ADP, future developments necessary to support adaptation of the approach to ATP-dependent enzymes are discussed.

High-performance affinity chromatography of NADP+ dehydrogenases from cell-free extracts using a nucleotide analogue as general ligand

An epoxy-activated silica column (50 cm x 0.45 cm I.D.) was derivatized with 8-[6-aminohexyl)amino]-2'-phosphoadenosine-5'-diphosphoribose; the bound ligand concentration was 11.4 mumol/g of dry silica, and the useful loading capacity was 2.3 mg of glutathione reductase. The new high-performance liquid chromatographic column specifically retained NADP(+)-dependent enzymes, which were quantitatively eluted specifically by NADP+ or, with better resolution, by potassium chloride. The new high-performance liquid chromatographic support was applied to the purification of glutathione reductase and glucose-6-phosphate dehydrogenase from cell-free extracts of baker's yeast, fish liver and rabbit hemolysates, with high recoveries and excellent purification factors.

Separation of nuclear cAMP independent protein kinases NI and NII from their chromosomal protein substrates and enzyme inhibitors by the use of a casein-phosvitin-Sepharose column

A casein-phosvitin-Sepharose chromatography column allows separation of nuclear protein kinases from their chromosomal phosphoprotein substrates and from at least some protein kinase inhibitors in a single step. The additional step of passing the eluted material through a partially hydrolyzed, dephosphorylated casein-Sepharose column separates the two protein kinases, NI and NII, from each other.

Catalytic and molecular properties of a highly purified G type casein kinase from bovine lung tissue

A preparation procedure has been worked out to obtain a highly purified G type (using GTP as well as ATP) casein kinase from large quantities of bovine lung tissue. It included ion-exchange (DEAE and phosphocellulose) and affinity (casein and ATP-Sepharose) chromatography combined with a flocculation step, and yielded an apparently homogeneous preparation with a 16% yield and a purification factor of more than 1400. The purified lung casein kinase used GTP (Km 16 microM) almost as well as ATP (Km 6.7 microM) and exhibited the major catalytic properties of the casein kinase G previously described in bovine adrenal cortex (Cochet, C., Job, D., Pirollet, F. and Chambaz, E.M. (1981) Biochim. Biophys. Acta 658, 191-201). Mg2+ (30-50 mM) and spermine (2 mM) were potent activators of lung casein kinase G activity, whereas the enzyme was inhibited by heparin and quercetin. The purified enzyme underwent self-phosphorylation in the presence of ATP or GTP, serine being the only target amino acid under these conditions, whereas both serine and threonine were phosphorylated by the enzyme in casein. Lung casein kinase G exhibited an apparent molecular weight between 140 000-160 000 upon gel filtration and appeared formed by the association of two different subunits upon SDS-polyacrylamide gel electrophoresis. The two subunits of Mr 38 000 (alpha) and 27 000 (beta) exhibited a 2:1 ratio upon quantitative scanning, suggesting an alpha 3 beta 2 combination in the oligomeric native enzyme structure. Peptide mapping of the two isolated subunits following 125I-labeling and papain digestion did not disclose any common fragment. The casein kinase catalytic activity was found associated with the alpha (38 kDa) enzyme subunit after recovery from gel electrophoresis in the presence of SDS, whereas the 27 kDa (beta) subunit was the major target of the enzyme self-phosphorylation reaction. alpha and beta subunits appeared strongly associated in the oligomeric enzyme and the possible role of the beta subunit in the casein kinase G activity remains to be examined. The purified casein kinase G, which can be obtained by the present procedure, should facilitate the study of the biological significance of this phosphorylation system in the intact cell.

Co-purification of coenzyme-dependent enzymes by affinity chromatography

Recent developments in general ligand affinity chromatography have greatly facilitated the purification of numerous coenzyme-dependent enzymes in practical scale. By immobilizing various derivatives of coenzymes (NAD+, NADP+, ATP and coenzyme A) on Sepharose, these general ligand affinity columns have the potential of enriching as many as 30% of the two thousand known enzymes as well as their isozymic forms, if they are applied in combination with the conventional procedures.

The relative conformational stability of the alcohol dehydrogenase alleloenzymes of the fruitfly Drosophila melanogaster

The effect of temperature on four purified alleloenzymes of the alcohol dehydrogenase (Adhs, Adhf, AdhD and Adhn-5) of the fruitfly Drosophila melanogaster was investigated in detail. Initial-velocity studies showed that the naturally occurring Adhf and Adhs enzymes differed only in their temperature optima, and evidence of kinetic adaptation to high and low temperature was not apparent. All four alleloenzymes denatured irreversibly on heating purified enzyme solutions at pH 6.0. This technique revealed only small differences in thermostability between Adhf and Adhs, although the two mutant enzymes from AdhD and Adhn-5 were considerably more labile. Electrophoresis of the enzymes though a stable transverse temperature gradient proved to be a discriminating and reproducible technique. Enzymes of different net charge were compared on the same polyacrylamide gel. The Adhf enzyme was shown to be significantly less stable than the Adhs enzyme. Subunit interchange was observed at temperatures below the point at which the unfolding occurred. At pH 4.0, the Adhf/Adhs heterodimer was as stable as the Adhs homodimeric enzyme, and more stable than the Adhf homodimer. Adhn-5 and AdhD alleloenzymes were relatively thermolabile. The stability of the alleloenzymes towards urea denaturation was studied by urea-gradient electrophoresis. Only small differences in stability between the Adhf and Adhs enzymes were observed. The AdhD and Adhn-5 mutants were denatured at the same urea concentration, which was much lower than in the case of the wild-type enzymes. Except at pH 4.0, subunit dissociation could not be distinguished from the unfolding of the monomer.

Immunological and biochemical analysis of a null mutant of alpha-glycerolphosphate dehydrogenase from Drosophila melanogaster

A Drosophila null mutant(BO-1-4) of alpha-glycerolphosphate dehydrogenase induced by ethylmethane sulfonate(EMS) was analyzed by double immunodiffusion, enzyme immunoinactivation, immunoelectrophoresis and two-dimensional electrophoresis. Based on all the immunological evidence, this mutant appears to express no protein that can cross-react with the antiserum specific to alpha-glycerolphosphate dehydrogenase. A protein spot corresponding to alpha-glycerolphosphate dehydrogenase was identified on two-dimensional gels of the soluble fly homogenates. The absence of this protein spor on two-dimensional gels of this null mutant further supported the immunological data. The activities of seven other enzymes in the related metabolic pathways were determined for the mutant and the control Drosophila. The null mutant does not show significant alterations in activities of these enzymes. The relationship between the deficiency of this enzyme and the inability for the sustained flight of the null mutant was discussed in terms of cellular metabolic regulations.

Photoaffinity labelling of arginine kinase and creatine kinase with a gamma-P-substituted arylazido analogue of ATP

1. An ATP analogue with a photoactivated azide group attached to the gamma-phosphate via an amide bond, ATP gamma-p-azidoanilide, appeared to have potential use as a photoaffinity label for the nucleotide-binding regions of ATP: guanidine phosphotransferases. Upon photolysis in the presence of lobster muscle arginine kinase and rabbit muscle creatine kinase, the analogue is converted to a potent inhibito of these two kinases. This photo-dependent inhibition is specific as it cannot be induced by azidoaniline, a mixture of azidoaniline and ATP or by ATP gamma-p-aminoanilide. Preirradiated under suitable conditions, the photoanalogue still shows a transitory inhibitory effect which, however, slowly vanishes with time (t0.5 = 3 h). 2. The photoinhibition is significantly decreased by the presence of ATP or ADP but is completely prevented by the addition of a mixture of nucleotide and guanidine substrates. Differential spectroscopy and affinity chromatography on Sepharose-ATP demonstrated the inability of photoinactivated arginine kinase and creatine kinase to recognize their nucleotide substrates. 3. Experiments with [14C]ATP gamma-p-azidoanilide indicated that photolysis is associated with an irreversible and stoichiometric binding of the ATP analogue to the enzymes. Autoradiographs made with the peptide maps corresponding to the tryptic digests of each 14C-labelled photomodified enzyme showed an unexpected highly specific labelling of the proteins. 4. Thiiol titrations of the kinases which have been subjected to various photolysis conditions led to the conclusion that the arylnitrene moiety of the photoanalogue is covalently attached to the single reactive cysteinyl side chain present in the active-site region of the two homologous kinases. This amino acid residue appears, therefore, to be located near the phosphate chain binding subsite occupied by the ATP analogue and probably also by the natural nucleotide substrates.

Biochemical and immunological characterization of genetic variants of phosphoglucose isomerase from mouse

Two electrophoretic variants of phosphoglucose isomerase (PGI) were purified from whole body extracts of DBA/2J and C57BL/6J mice by a substrate-affinity elution from an 8-(6-aminohexyl)amino-ATP-Sepharose column followed by preparative isoelectric focusing. Both PGI variants were shown to be dimers of the same molecular weight, sedimentation coefficient, and Km for fructose-6-phosphate. The isoelectric points were found to be 8.4 and 8.7 for variants from DBA/2J and C57BL/6J mice, respectively. Differential thermal stability was observed for the two variants in 0.1 M tris-HCl buffer, pH 8.0, at 54 C; the half-lives of the purified PGI from DBA/2J and C57BL/6J mice were shown to be 3.4 and 1.8 min, respectively, under those conditions. Similar differences were observed for the enzyme variants in the crude homogenates. Antisera against PGI from DBA/2J mice were raised in rabbits. The variants from DBA/2J and C57BL/6J mice showed no significant differences in their respective inactivation curves by the antisera. Results of amino acid composition analyses and peptide mappings of the two PGI variants indicate that the genetic variation of this enzyme might result from a single charged amino acid substitution.

Biochemical characterization of phosphoglucose isomerase and genetic variants from mouse and Drosophila melanogaster

A simple and unique procedure was developed to purify phosphoglucose isomerase variants from the whole mouse body extracts and Drosophila homogenate. It involved the use of an 8-(6-aminohexyl)-amino-ATP-Sepharose column followed by a preparative isoelectric focusing. In each case, the enzyme in the homogenate was adsorbed by ionic interaction on the ATP-Sepharose column. Substantial purification was achieved by the affinity elution with the substrate-glucose-6-phosphate. Mouse and Drosophila phosphoglucose isomerase as well as the corresponding variants were shown to be dimers of similar molecular weight and to exhibit similar kinetic properties. The isoelectric points for the variants from DBA/2J and C57BL/6J mice were determined to be 8.4 and 8.7 respectively, while they were 6.8 and 6.3 respectively for Drosophila and 4/4 variants. Differential thermal stability was observed for the two mouse variants but not for the Drosophila ones. Amino acid composition analysis was performed for both mouse and Drosophila enzymes. Rabbit antisera for mouse (DBA/2J) and Drosophila (2/2) enzymes were raised. Within each species, complete immunological identity was observed between the variants. The antisera were used to characterize the null mutants of phosphoglucose isomerase identified in the mouse and Drosophila populations. By rocket immunoelectrophoresis, the null allele of the naturally occurring heterozygous null variant of Drosophila was shown to express no cross-reacting materials (CRM).

Analyses of mouse and Drosophila proteins by two-dimensional gel electrophoresis

Two-dimensional gel electrophoresis was employed for the protein analysis of several different mouse tissues and Drosophila. The number of protein spots detected with conventional protein dye staining techniques ranged from 110 in erythrocyte lysate to 320 in liver homogenate. Strain variation of protein spots on the gels was examined in five different tissues from two strains of inbred mice (DBA/2J and C57BL/6J) and their F1 hybrids. The protein spots which exhibited strain variation were shown to be autosomally inherited and to follow Mendelian genetics. From these analyses, it was shown that the frequencies of protein variations between these two strains of mice vary from 1 to 5% with the tissue examined. During the course of this study, the protein spots corresponding to nine muscle proteins and three testis enzymes from the mouse as well as two Drosophila enzymes were assigned on two-dimensional gels of their respective homogenates. Radioisotope labelling of Drosophila and autoradiography of the two-dimensional gels were also performed to improve the sensitivity and resolution of the technique. The potential application of two-dimensional gel electrophoresis for mutant screening as well as biochemical genetic studies is discussed.

Mouse-liver glutathione reductase. Purification, kinetics, and regulation

Glutathione reductase from the liver of DBA/2J mice was purified to homogeneity by means of ammonium sulfate fractionation and two subsequent affinity chromatography steps using 8-(6-aminohexyl)-amino-2'-phospho-adenosine diphosphoribose and N6-(6-aminohexyl)-adenosine 2',5'-biphosphate-Sephadex columns. A facile procedure for the synthesis of 8-(6-aminohexyl)-amino-2'-phospho-adenosine diphosphoribose is also presented. The purified enzyme exhibits a specific activity of 158 U/mg and an A280/A460 of 6.8. It was shown to be a dimer of Mr 105000 with a Stokes radius of 4.18 nm and an isoelectric point of 6.46. Amino acid composition revealed some similarity between the mouse and the human enzyme. Antibodies against mouse glutathione reductase were raised in rabbits and exhibited high specificity. The catalytic properties of mouse liver glutathione reductase have been studied under a variety of experimental conditions. As with the same enzyme from other sources, the kinetic data are consistent with a 'branched' mechanism. The enzyme was stabilized against thermal inactivation at 80 degrees C by GSSG and less markedly by NADP+ and GSH, but not by NADPH or FAD. Incubation of mouse glutathione reductase in the presence of NADPH or NADH, but not NADP+ or NAD+, produced an almost complete inactivation. The inactivation by NADPH was time, pH and concentration dependent. Oxidized glutathione protected the enzyme against inactivation, which could also be reversed by GSSG or other electron acceptors. The enzyme remained in the inactive state even after eliminating the excess NADPH. The inactive enzyme showed the same molecular weight as the active glutathione reductase. The spectral properties of the inactive enzyme have also been studied. It is proposed that auto-inactivation of glutathione reductase by NADPH and the protection as well as reactivation by GSSG play in vivo an important regulatory role.

Purification and properties of acetate kinase from Acholeplasma laidlawii

Acetate kinase (EC 2.7.2.1) was purified from Acholeplasma laidlawii cytoplasm by a combination of ammonium sulfate fractionation, gel filtration, diethylaminoethyl-cellulose chromatography, and affinity chromatography on 8-(6-aminohexylamino)-adenosine 5'-triphosphate conjugated to Sepharose 4B. The enzyme was composed of polypeptide chains of about 50,000 molecular weight as estimated from sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Under nondenaturating conditions, apparent molecular weights between 64,000 and 130,000 were obtained, depending upon mainly the ionic strength of the test solution. The enzyme had a narrow specificity for phosphate acceptor acids, whereas both purine and pyrimidine nucleoside triphosphates were suitable phosphate donors. Na(+) and K(+) inhibited both acetyl phosphate and adenosine 5'-triphosphate synthesis, and the latter was also inhibited by high concentrations of adenosine 5'-diphosphate and acetyl phosphate. This substrate inhibition was partially abolished by 0.5 M NaCl. The enzyme catalyzed the independent adenosine 5'-diphosphate<-->adenosine 5'-triphosphate and acetate<-->acetyl phosphate exchanges. The rate of the latter was enhanced by the addition of cosubstrate Mg(2+)-adenosine 5'-triphosphate. The high affinity for substrates, except for acetate, indicated that under physiological conditions the direction of the enzymic reaction favors adenosine 5'-triphosphate synthesis. Thus, a mechanism for adenosine 5'-triphosphate generation in mycoplasmas is suggested.

Purification of four pyruvate kinase isozymes of rats by affinity elution chromatography

1. Purification of four isozymes of pyruvate kinase (ATP:pyruvate 2-O-phosphotransferase, EC 2.7.1.40) L, M1, M2 and R was much improved to give good yields by affinity elution chromatography. The enzyme was eluted from a phosphocellulose column with 0.5 mM phosphoenolpyruvate. Types L, M2 and R were stabilized with fructose 1,6-diphosphate throughout the purification procedures. 2. The isozymes were crystallized under various conditions: types L and R were readily crystallized from medium of low ionic strength, types L, M1, and M2 were crystallized from ammonium sulfate solution in different forms in the presence and absence of phosphoenolpyruvate. Type M1 was also crystallized in different forms in the presence and absence of fructose 1,6-diphosphate. 3. Amino acid analyses showed that the compositions of types L and R, and of types M1 and M2, respectively, were very similar.

Purification and characterization of two isozymes of 3-phosphoglycerate kinase from the mouse

Two isozymes of 3-phosphoglycerate kinase (ATP:3-phospho-D-glycerate 1-phosphotransferase, EC 2.7.2.3), designated PGK-A and PGK-B, were purified from separate extracts of muscle and testicular tissue of DBA/2J mice, respectively. A similar procedure was used to purify the corresponding isozymes from C57BL/6J mice in order to make inter-strain comparisons. The purification involved the use of affinity chromatography with an 8-(6-aminohexyl)amino-ATP-Sepharose column and DEAE-Sephadex chromatography. Lactate dehydrogenase isozyme LDH-X was also co-purified from extract of mouse testes by this two-step procedure. The same isozyme isolated from either mouse strain was found to be identical in physical and biochemical properties. Both isozymes are monomeric as determined by gel filtration chromatography and by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Furthermore, the isozymes have similar molecular weights, of 47 000 +/- 2000 and exhibit similar Km values for both coenzymes and substrate, as well as temperature dependence of enzyme activity. However, it was observed that the B isozyme is more labile than the A isozyme by denaturation at high temperature, urea and acidic pH.