Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:4.1.2.13 (aldolase)
 3,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Measurements of ammonia release provide the first direct evidence that calmodulin becomes extensively deamidated during incubations at 37 degrees C, pH 7.4 or pH 11. A stoichiometry of 0.5 mol of NH3 released/mol of calmodulin is observed after 2 h at pH 11 or after 8-9 days at pH 7.4. These treatments also increase the ability of calmodulin to serve as a substrate for the isoaspartate-specific protein carboxyl methyltransferase from bovine brain. The stoichiometries of methylation are highly correlated with the stoichiometries of ammonia release. Deamidation and increased methyl-accepting capacity also occur in parallel for seven other proteins (aldolase, bovine serum albumin, cytochrome c, lysozyme, ovalbumin, ribonuclease A, and triosephosphate isomerase) upon incubation at pH 11. However, in comparison to calmodulin, these other proteins show very little deamidation and increased methylation capacity following incubation at pH 7.4. Deamidation of calmodulin at pH 7.4 is unaffected by the addition of 10(-7) M Ca2+; however, at 4 X 10(-6) M Ca2+, the rate of deamidation is inhibited by approximately 70%. The Ca2+-protection effect is consistent with the suggestion (B. A. Johnson, N. E. Freitag, and D. W. Aswad, (1985) J. Biol. Chem. 260, 10913-10916) that deamidation occurs preferentially at Asn-60 and/or Asn-97, each of which resides in a distinct Ca2+-binding domain.
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PMID:Deamidation of calmodulin at neutral and alkaline pH: quantitative relationships between ammonia loss and the susceptibility of calmodulin to modification by protein carboxyl methyltransferase. 291 79

Ribonuclease A was introduced into the cytoplasm of IMR-90 human diploid fibroblasts by red cell-mediated microinjection. Early passage fibroblasts degraded ribonuclease A with a half-life of approximately 90 h in the presence of 10% fetal calf serum and enhanced the degradative rate 1.6-fold upon serum withdrawal. Senescent cells degraded ribonuclease A more slowly with half-lives ranging between 125 and 250 h and had diminished capacities to enhance the catabolism of this protein during serum starvation. Decreased protein degradation in senescent cells was also evident for microinjected RNase S-protein, RNase B, aldolase, lysozyme, and the synthetic copolymer polyglutamate: tyrosine:alanine (1:1:1). These alterations in the mechanisms and regulation of intracellular protein degradation may contribute to several biochemical abnormalities characteristic of aging cells and organisms.
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PMID:Altered degradation of proteins microinjected into senescent human fibroblasts. 717 58

The immunologic relatedness of various cofactor-binding sites of enzymes requiring different nucleotide cofactors was examined. Chicken antibodies specific for NADPH- or CoA-binding domains were raised using an NADPH- or CoA-requiring enzyme as an immunogen. Antibodies specific for either NADPH- or CoA-binding domains were isolated by immunoaffinity chromatography of the respective antisera using unrelated NADPH- or CoA-requiring enzymes as affinity ligands. The reactivities of the NADPH- and CoA-binding-site-specific antibodies with a variety of enzymes that required different cofactors was shown on Western blots of SDS-PAGE of the enzymes. Variable cross-reactivities were observed among all nucleotide-cofactor requiring enzymes with each specific cofactor-domain-antibody population. Numerous proteins not physiologically associated with nucleotide cofactors, including acyl carrier protein, were completely unreactive. Proteins that bound phosphoryl compounds either as substrates or cofactors showed varying degrees of reactivity with each population of specific antibodies. These included aldolase, ribulose-1,5-bisphosphate carboxylase/oxygenase, ribonuclease A, carbonic anhydrase and triosephosphate isomerase. The immunologic cross-reactivity suggested that these proteins share a common structural feature, probably a primary structure epitope, since the proteins had been subjected to denaturing polyacrylamide gel electrophoresis. A candidate for this common structural feature is a glycine-rich sequence comprising a phosphate binding loop.
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PMID:Nucleotide cofactor-binding-domain-specific antibodies show immunologic relatedness among unrelated proteins that bind phosphoryl compounds. 845 96

Previous studies of protein evolution have identified important mutations in various proteins that affect a small number of residues, but dramatically alter protein function. However, the evolutionary process underlying the three-dimensional protein properties, which are determined by a much larger number of residues, remains unclear. Based on a comparative evolutionary analysis of teleost phosphoglucose isomerases (PGIs; EC 5.3.1.9), we previously demonstrated that the relatively weak selection on many amino acid sites has played an important role in the evolution of protein electric charge as a model of three-dimensional protein properties. To ascertain the generality of this finding, we sought further evidence of this type of protein evolution. For this purpose, we analyzed the vertebrate isoforms of fructose-1,6-bisphosphate aldolase (ALD; EC 4.1.2.13), for which electric charges are known to have diverged after gene duplication. The results showed that the divergence in electric charge between the ALD isoforms was also driven by weak selection on many amino acid sites, as in PGI, confirming the generality of earlier findings. To obtain further insights, ALD and PGI were compared to the proteins pancreatic ribonuclease (EC 3.1.27.5) and triose-phosphate isomerase (EC 5.3.1.1), for which electric charges likely evolved through a well-defined mode of molecular evolution; namely, strong selection on specific amino acid sites. Comparison of the number and composition of amino acids on the protein surface suggested that the absolute number of evolutionarily changeable amino acids in a protein affects the strength of selection pressure acting on individual amino acid sites.
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PMID:Electric charge divergence in proteins: insights into the evolution of their three-dimensional properties. 1865 81

A monolithic wide-pore silica column was newly prepared for protein separation. The wide distribution of the pore sizes of monolithic columns was evaluated by mercury porosimetry. This column, as well as the conventional monolithic column, shows high permeability in the chromatographic separation of low-molecular-sized substances. In higher-molecular-sized protein separation, the wide-pore monolithic silica column shows better performance than that of the conventional monolithic column. Under optimized conditions, five different proteins--ribonuclease A, albumin, aldolase, catalase, and ferritin--were baseline-separated within 3 min, which is faster than that using the particle-packed columns. In addition, the monolithic wide-pore silica column could also be prepared in fused silica capillary (600 mm long, 0.2 mm i.d.) for highly efficient protein separation. The peak capacity of the wide-pore monolithic silica capillary column is estimated to be approximately 300 in the case of protein separation, which is a characteristic performance.
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PMID:Performance of wide-pore monolithic silica column in protein separation. 1957 77