Two isozymes of chicken muscle acylphosphatase: purification and properties

Two acylphosphatases, named Ch1 and Ch2, have been purified from chicken skeletal muscle. The molecular weights were determined to be 11,900 and 12,000 for Ch1 and Ch2, respectively, by sedimentation equilibrium. In the amino acid compositions of Ch1 and Ch2, two residues of histidine were contained in Ch2, but none in Ch1, and one residue of cysteine was contained in Ch1, but none in Ch2. There were 11 lysines and 6 arginines in Ch1, whereas there were 6 lysines and 11 arginines in Ch2. In addition, the contents of methionine, serine, glutamic acid and glutamine, and alanine were considerably different between Ch1 and Ch2. There were also differences in the peptide maps and carboxyl-terminal amino acid sequences (-Ser-Thr-Arg-Tyr-COOH for Ch1, and -Phe-Thr-Ile-Arg-Lys-COOH for Ch2). In the double immunodiffusion, Ch2 did not form a precipitin line with the rabbit anti-Ch1 antiserum. These results indicate that Ch1 and Ch2 are different, genetically specified isozymes of acylphosphatase of chicken skeletal muscle. Ch2 is considered to be a new type of acylphosphatase from skeletal muscle.     

Ontogenic expression of the two isozymes, Ch1 and Ch2, of chicken muscle acylphosphatase

Activities of the two isozymes, Ch1 and Ch2, of chicken muscle acylphosphatase were measured in breast muscles, leg muscles, and livers of developing chicks from day 11 in ovo to day 15 of free life. Measurement was performed using rabbit antibodies which could selectively precipitate Ch1 or Ch2. The activity contents of both Ch1 and Ch2 in muscles were low before hatching but rapidly increased after hatching. Ch1 showed a more marked increase than Ch2. In liver, on the other hand, the activity contents of Ch1 and Ch2 remained low throughout the period of pre- and post-hatching.     

Distribution of AMP-deaminase isozymes in rat tissues

1. The distribution of AMP deaminase isozymes in rat tissues was analyzed by electrophoresis on cellulose acetate membrane, by chromatography on phosphocellulose column, and by the application of immunological technique employing specific antisera against three parental AMP deaminases (isozymes A, B and C). Skeletal muscle extracts and diaphragm extracts contain a single identical isozyme, isozyme A. The major isozyme species of liver, kidney and testes are also identical and they are isozyme B. Heart extracts contains isozyme C exclusively. Extracts of brain, lung and spleen contain five isozymes, presumably a complete set of five B-C hybrids. 2. Developmental patterns of AMP deaminase isozyme were studied. In early postnatal life, extracts of heart, liver, kidney and lung contain five isozymes similar to those observed in adult brain. During postnatal development, a shift to isozyme C occurs in heart, whereas a shift to isozyme B occurs in liver and kidney. Five isozymes in lung remain throughout development. In brain a shift of B to five isozymes is observed during development. Isozyme A is the predominant form in muscle throughout postnatal development. 3. AMP deaminase in the regenerating liver was analyzed, but the data indicated that there was no change of isozyme distribution during hepatic regeneration.     

Purification and properties of porcine testis acylphosphatase

Acylphosphatase has been purified from porcine testis and its properties were compared with those of porcine skeletal muscle acylphosphatase. The molecular weight of the testis enzyme was found to be 10,600, similar to that of porcine skeletal muscle acylphosphatase, on sedimentation equilibrium analysis. The specific activity of the testis enzyme was 10,800 mumol/min/mg at 25 degrees C with benzoyl phosphate as substrate, i.e., higher than that of the muscle enzyme, 7,200 mumol/min/mg, under the same conditions. The pI of the testis enzyme was 8.3, i.e., lower than that of the muscle enzyme, 10.6. There were marked differences in the amino acid compositions of the two enzymes. In particular two histidine residues were present in the testis enzyme but none were present in the muscle enzyme, and no cysteine residue was present in the testis enzyme but one was present in the muscle enzyme. The carboxyl terminal amino acid of the testis enzyme seemed to be lysine, while that of the muscle enzyme is tyrosine. The peptide maps of the testis and muscle enzymes indicated considerable differences in the amino acid sequences of the two enzymes. Differences in the antigenic structures of the two enzymes were demonstrated on enzyme linked immunoassaying and double immunodiffusion. These results indicate that the porcine testis acylphosphatase is an isozyme different from the porcine skeletal muscle acylphosphatase.     

Distribution of hepatic phosphofructokinase isozymes in parenchymal and sinusoidal cells.

The distribution profile of the isozymes of phosphofructokinase (PFK) in different cell types of rat liver is established using the techniques of electrophoresis and immunodiffusion. Agarose gel electrophoresis of the extracts of parenchymal cells, Kupffer or sinusoidal cells, and whole liver indicated that two PFK isozymes are present in whole liver and that the faster moving hepatic PFK isozyme is present only in parenchymal cells; whereas, the slower moving hepatic PFK isozyme is only in sinusoidal cells. Immunodiffusion studies using antiserum specific for the major hepatic PFK isozyme (PFK-L₂) revealed that PFK-L₂ is present only in whole liver or parenchymal cell extracts and is absent from sinusoidal cells. It is apparent that the other hepatic PFK isozyme (PFK-L₁) is normally found only in sinusoidal cells.     

Distribution of dopa-oxidase isozymes among mosquito vectors of viral encephalitis

Distribution of DOPA-oxidase isozymes in larval Culex pipiens pipiens, Culex pipiens quinquefasciatus and their hybrids was determined by agarose gel electrophoresis. Three zones of enzyme activity were detected in the subspecific and hybrid populations. Zone I was cathodic whereas Zones II and III were anodic. Electrophoretic variability was evident only in Zone II which was dimorphic for enzyme activity. Zones I and III were monomorphic. The subspecific and hybrid populations were distinguishable from one another only in Zone II. In all three populations, melanization was most intense in Zone II, less in Zone I, and least in Zone III.     

Distribution of AMP deaminase isozymes in various human blood cells

Column chromatographic, electrophoretic and immunological studies showed the distribution of AMP deaminase isozymes in human blood cells as follows; isozyme E1 in erythrocyte, E2 in granulocyte, L in mononuclear cells, platelets and T-lymphoblast, and probably E1-L hybrid sets in B-lymphoblast.     

Horse heart acylphosphatase: purification and characterization

The use of an affinity chromatography step performed with an immunoadsorbent consisting of anti-horse muscle acylphosphatase antibodies covalently linked to Sepharose 4B allowed us to purify horse heart acylphosphatase in a very rapid and efficient fashion. As in skeletal muscle, also in heart the enzyme is present as both a mixed disulfide with glutathione and a S-S dimer. The abundance of these forms in heart is quite lower than in skeletal muscle. The comparison of the molecular forms so purified with those obtained from horse skeletal muscle showed the same aminoacid composition, tryptic fingerprint, together with strictly similar apparent molecular weight and main kinetic parameters, supporting the conclusion that the acylphosphatase present in heart is the same enzyme as that purified from skeletal muscle.     

N-acetylserine in horse muscle acylphosphatase.

A ninhydrin-negative peptide fraction obtained from tryptic digest of carboxymethyl acylphosphatase was isolated by chromatography on a column of PA 28 Beckman resin and analysed for the amino acid composition. Degradation with carboxypeptidase B and A indicated that the sequence of this peptide was: X-Thr-Ala-Arg. The amino-terminal residue was identified as N-acetylserine by high voltage electrophoresis. It is therefore suggested that the sequence of the NH2-terminal portion of CM-acylphosphatase is N-acetyl-Ser-Thr-Ala-Arg. Digestion with carboxypeptidase A and B indicated also that the COOH-terminal portion of CM-acylphosphatase is-Arg-Tyr-OH.     

Distribution and properties of myosin isozymes in developing avian and mammalian skeletal muscle fibers

Isozymes of myosin have been localized with respect to individual fibers in differentiating skeletal muscles of the rat and chicken using immunocytochemistry. The myosin light chain pattern has been analyzed in the same muscles by two-dimensional PAGE. In the muscles of both species, the response to antibodies against fast and slow adult myosin is consistent with the speed of contraction of the muscle. During early development, when speed of contraction is slow in future fast and slow muscles, all the fibers react strongly with anti-slow as well as with anti-fast myosin. As adult contractile properties are acquired, the fibers react with antibodies specific for either fast or slow myosin, but few fibers react with both antibodies. The myosin light chain pattern slow shows a change with development: the initial light chains (LC) are principally of the fast type, LC1(f), and LC2(f), independent of whether the embryonic muscle is destined to become a fast or a slow muscle in the adult. The LC3(f), light chain does not appear in significant amounts until after birth, in agreement with earlier reports. The predominance of fast light chains during early stages of development is especially evident in the rat soleus and chicken ALD, both slow muscles, in which LC1(f), is gradually replaced by the slow light chain, LC1(s), as development proceeds. Other features of the light chain pattern include an "embryonic" light chain in fetal and neonatal muscles of the rat, as originally demonstrated by R.G. Whalen, G.S. Butler- Browne, and F. Gros. (1978. J. Mol. Biol. 126:415-431.); and the presence of approximately 10 percent slow light chains in embryonic pectoralis, a fast white muscle in the adult chicken. The response of differentiating muscle fibers to anti-slow myosin antibody cannot, however, be ascribed solely to the presence of slow light chains, since antibody specific for the slow heavy chain continues to react with all the fibers. We conclude that during early development, the myosin consists of a population of molecules in which the heavy chain can be associated with a fast, slow, or embryonic light chain. Biochemical analysis has shown that this embryonic heavy chain (or chains) is distinct from adult fast or slow myosin (R.G. Whalen, K. Schwartz, P. Bouveret, S.M. Sell, and F. Gros. 1979. Proc. Natl. Acad. Sci. U.S.A. 76:5197-5201. J.I. Rushbrook, and A. Stracher. 1979. Proc Natl. Acad. Sci. U.S.A. 76:4331-4334. P.A. Benfield, S. Lowey, and D.D. LeBlanc. 1981. Biophys. J. 33(2, Pt. 2):243a[Abstr.]). Embryonic myosin, therefore, constitutes a unique class of molecules, whose synthesis ceases before the muscle differentiates into an adult pattern of fiber types.     

Characterization of a novel Drosophila melanogaster acylphosphatase

Analysis of the Drosophila melanogaster EST database led to the characterization of a novel acylphosphatase (AcPDro2). This is coded by the CG18505 (Acyp2) gene and is clearly distinct from a previously described AcPDro coded by the CG16870 (Acyp) gene from D. melanogaster. The two proteins show a 60% homology with both vertebrate isoenzymes. All the residues involved in the catalytic mechanism are conserved. AcPDro2 is a stable enzyme with a correct globular folded structure. Its activity on benzoylphosphate shows higher K(cat) but lower K(m) with respect to AcPDro. It is possible that AcPDro and AcPDro2 genes are not the direct ancestor of MT and CT vertebrate isoenzymes.     

Turkey muscle acylphosphatase: purification and comparative studies

Turkey muscle acylphosphatase is strongly bound to anti-(horse muscle acylphosphatase ) antibodies covalently linked to an agarose resin. This permits use of an affinity chromatography step in the purification, which increased the final yield and allowed us to isolate three different molecular forms of the enzyme. Form 1 is a mixed disulfide between the polypeptide chain and glutathione; form 3 is an S-S dimer of the polypeptide chain present in form 1, while form 2, present in a very low amount, consists of a polypeptide chain quite similar in aminoacid composition to that found in form 1. The three molecular forms show very similar kinetic parameters. The comparison of these molecular forms with those isolated from horse muscle showed similar kinetic properties but different structural features.     

Immunoaffinity purification and immunoassay determination of human erythrocyte acylphosphatase

Specific anti-human erythrocyte acylphosphatase antibodies were raised in rabbits, purified by affinity chromatography, and used to develop an enzyme purification procedure based on an immunoaffinity chromatography step. This procedure permitted the rapid purification of the enzyme, with a high final yield and with a specific activity very similar to that found for the enzyme purified by the standard procedure. The noncompetitive enzyme-linked immunoadsorbent assay developed with the affinity-purified antibodies was very specific and sensitive in that a positive reaction could be detected in the presence of antigen amounts of as little as 0.01 ng/ml. By this assay the enzyme content was determined in normal cells, tissues, and organs as well as in blood samples from hemopathy-affected patients. This test could possibly have clinical applications.     

Crystallization and properties of acylphosphatase from porcine skeletal muscle

A crystalline acylphosphatase has been obtained from porcine skeletal muscle. The purification procedure consists of extraction with water, phosphocellulose column chromatography, CM-cellulose column chromatography, and crystallization. The enzyme was homogeneous by polyacrylamide gel electrophoresis. A high yield (39%) of the pure enzyme was attained by the use of buffers containing 10 mM 2-mercaptoethanol to prevent dimerization of the enzyme in the purification process. Activity assay in the presence of bovine serum albumin showed a high specific activity of the enzyme (about 7,000 mumol/min/mg at 25 degrees C with benzoyl phosphate as substrate). The molecular weight was determined to be 11,100 by sedimentation equilibrium. The amino acid composition of the enzyme was determined. The amino-terminus of the enzyme was blocked and the carboxyl-terminal residue was tyrosine.     

Distribution of alpha-amylase isozymes among the varieties of winter wheat in Russia and Ukraine

A catalog of winter wheat varieties bred in Russia and Ukraine for alpha-amylase isozymes is presented. Among them, 11 phenotypic classes were found. It was established that the observed differences in the frequency of specific phenotypes for alpha-amylase in the culture of winter wheat depended on the geographical origin. The percentage of the most widespread cultural phenotype, designated as AbCde, decreased from the south (45°–46° N) to the north (49°–50° N) by 31.0%. At the same time, the frequency of the abCde variant increased by 25.0%. The distribution of the Abcde phenotype changed significantly from 20.7% in the west (30o36′ E) to 0% in the east (40o18′ E). The observed territorial dynamics for alpha-amylase isoenzymes may indicate the adaptive value of the identified phenotypes of common winter wheat for the weather and climatic conditions of the region of their origin.     

Mutational analysis of the aggregation-prone and disaggregation-prone regions of acylphosphatase

We have performed an extensive mutational analysis of aggregation and disaggregation of amyloid-like protofibrils of human muscle acylphosphatase. Our findings indicate that the regions that promote aggregation in 25% (v/v) 2,2,2 trifluoroethanol (TFE) are different from those that promote disaggregation under milder conditions (5% TFE). Significant changes in the rate of disaggregation of protofibrils in 5% TFE result not only from mutations situated in the regions of the sequence that play a key role in the mechanism of aggregation in 25% TFE, but also from mutations located in other regions. In order to rationalise these results, we have used a modified version of the Zyggregator aggregation propensity prediction algorithm to take into account structural rearrangements of the protofibrils that may be induced by changes in solution conditions. Our results suggest that a wider range of residues contributes to the stability of the aggregates in addition to those that play an important kinetic role in the aggregation process. The mutational approach described here is capable of providing residue-specific information on the structure and dynamics of amyloid protofibrils under conditions close to physiological and should be widely applicable to other systems.