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

Conditions were determined in which approximately one mole of omicron-phthalaldehyde reacts with one mole of aldolase subunit yielding a stable fluorescent isoindole derivative. During this chemical modification, a linear relationship was observed between the enzyme inactivation and absorbance change (337 nm) or fluorescence change (lambda em 420 nm, and lambda ex 338 nm) characteristic for isoindole ring formation. The reaction follows second-order kinetics, k = 1.1 X 10(3) M-1 S-1, in 50 mM borate buffer, pH 8.4 at 25 degrees C. The modification of aldolase results in loss of approximately one -SH group per protein subunit. The enzyme is protected against modification by substrates and competitive inhibitors. Essentially no isoindole derivative is formed when the glycerol-1-phosphate-lysyl derivative of aldolase is used for modification studies. It is concluded that aldolase modification occurs at the active-site region. Isolation of cross-linked peptides suggests that Lys-227 and Cys-336 are involved in formation of the isoindole derivative. This result supports Cys-336 as the active-site cysteine necessary for aldolase catalytic activity. Fluorescence studies have shown that the isoindole group linked to aldolase has its lambda max, em markedly shifted toward shorter wavelength in comparison to the fluorescence of free isoindole derivatives in aqueous solution. In model studies a linear relationship between lambda max, em of 1-(beta-hydroxyethylthio)-2-beta-hydroxyethylisoindole and the solvent polarity or acidity was observed. The results of the studies suggest that the microenvironment of the cleft in aldolase which binds isoindole appears to be of low acidity and low polarity. The apparent low polarity experienced by the isoindole probe may be due to its location in an actual low-polarity portion of the active site, or may be due to non-relaxing surroundings of the probe.
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PMID:o-Phthalaldehyde, a fluorescence probe of aldolase active site. 666 5

This article identifies novel factors involved in cholesterol reduction by probiotic bacteria, which were identified using genetic and proteomic approaches. Approximately 600 Lactobacillus acidophilus A4 mutants were created by random mutagenesis. The cholesterol-reducing ability of each mutant was determined and verified using two different methods: the o-phthalaldehyde assay and gas chromatographic analysis (GC). Among screened mutants, strain BA9 showed a dramatically diminished ability to reduce cholesterol, as demonstrated by a 7.7% reduction rate, while the parent strain had a more than 50% reduction rate. The transposon insertion site was mapped using inverse PCR (I-PCR), and it was determined using bioinformatic methods that the deleted region contained the Streptococcus thermophilus catabolite control protein A gene (ccpA). In addition, we have shown using two-dimensional gel electrophoresis (2-DE) that several proteins, including a transcription regulator, FMN-binding protein, major facilitator superfamily permease, glycogen phosphorylase, the YknV protein, and fructose/tagatose bisphosphate aldolase, were strongly regulated by the ccpA gene. In addition, in vivo experiments investigating ccpA function were conducted with rats. Rats fed wild-type L. acidophilus A4 showed a greater than 20% reduction in total serum cholesterol, but rats fed BA9 mutant L. acidophilus showed only an approximately 10% reduction in cholesterol. These results provide important insights into the mechanism by which these lactic acid bacteria reduce cholesterol.
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PMID:Genetic and proteomic analysis of factors affecting serum cholesterol reduction by Lactobacillus acidophilus A4. 2049 44