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)

We isolated membranes from leupeptin-induced autophagic vacuoles and compared them with lysosomal membranes purified from dextran-administered rats. In protein composition, autophagic vacuole membranes prepared from long term-starved (36 h) rats bear marked resemblance to lysosomal membranes, whereas vacuole membranes prepared from short term-starved (12 h) animals differ significantly from lysosomal membranes. Immunoblotting analyses showed that only autophagic vacuole membranes from short term-starved rats possess endoplasmic reticulum markers such as cytochrome P450 and NADPH-cytochrome c reductase. None of the membranes contain sialyltransferase, a Golgi membrane marker. In experiments in which rats were starved after feeding to induce autophagy, the appearance of the endoplasmic reticulum markers occurred during 6-12 h of starvation, concomitantly with increases in vacuolar proteins and sequestered cytosolic aldolase. The endoplasmic reticulum membrane markers and sequestered aldolase declined gradually after 20-36 h of starvation, suggesting that prolonged starvation causes no further increase in the formation of autophagic vacuoles but an increase in the population of matured autophagic vacuoles. Thus, the prominent markers of endoplasmic reticulum from which autophagosomes originate are well preserved in autophagic vacuole membranes, and retention of these markers is highly dependent on the formation and subsequent maturation process of autophagic vacuoles.
 ...
PMID:Membrane markers of endoplasmic reticulum preserved in autophagic vacuolar membranes isolated from leupeptin-administered rat liver. 191 14

This study uses microsomal membranes from rat testis tissue, including the cytochrome P450c17 (steroid 17 alpha-monooxygenase/17 alpha-hydroxyprogesterone aldolase, catalyzing the conversion of progesterone to androstenedione), to decipher the possible relation of NADPH-induced (no exogenous iron added) lipid peroxidation and cytochrome P450 inactivation and the protective effect of certain steroids. NADPH (300 microM) causes a 3.6-fold stimulation of malondialdehyde formation (thiobarbituric acid-reactive substances) and a 29% cytochrome P450c17 loss within 1 h at 37 degrees C, but has no effect on lipid peroxidation in the presence of the iron chelator desferrioxamine. Hydrogen peroxide has only marginal effects. The antioxidant efficiency of estradiol (IC50 = 13.9 microM) is higher than its cytochrome P450c17 protective efficiency (IC50 = 33.0 microM), whereas androstenedione does not inhibit lipid peroxidation but protects cytochrome P450c17 completely. The human choriogonadotropin-induced degradation of cytochrome P450c17 in incubated decapsulated testes can not be correlated with a stimulation of lipid peroxidation, and it is partially inhibited by estradiol but completely abolished by androstenedione. It is concluded (I) that NADPH stimulates iron-dependent generation of reactive oxygen species by the monooxygenase system even in the presence of certain P450 ligands in the physiological membrane environment, (II) that membrane lipid peroxidation may be suppressed by hydrophobic steroids acting as antioxidants such as estradiol, (III) that steroid ligands stabilize cytochrome P450c17 against inactivation in the presence of NADPH even if they do not act as substrates and do not possess antioxidant activity, and (IV) that the choriogonadotropin-induced down-regulation of cytochrome P450c17 is not due to accumulating steroids acting as "pseudosubstrates" as occasionally supposed.
 ...
PMID:Novel connections between NADPH-induced lipid peroxidation and cytochrome P450 inactivation, and antioxidant and enzyme protective properties of estradiol in gonadal membranes. 925 24

Stable lysine adducts were formed in proteins following reaction with trichloroethylene (TCE) oxide, the major reactive compound generated by the metabolism of TCE. The order of formation of these adducts is N(6)-formyllysine > N(6)-(dichloroacetyl)lysine >> N(6)-glyoxyllysine, with the ratio being influenced by the particular protein. Protein lysine adducts were also analyzed following the enzymatic oxidation of TCE with several different cytochrome P450 (P450) enzyme systems. The ratio of formyl/dichloroacetyl lysine adducts was influenced by the enzyme system that was used. Chloral and TCE oxide formation was more extensive with rat liver microsomes isolated from phenobarbital-treated rats than with rat microsomes in which P450 2E1 was induced by treatment with isoniazid or in human P450 2E1 systems. Glutathione (GSH) and GSH transferase had inhibitory effects on the reaction of TCE oxide with albumin, with formylation being atteunated much more than the formation of dichloroacetyllysine. GSH is likely to react with the reactive acyl chloride intermediates formed from TCE oxide hydrolysis, instead of direct reaction with TCE oxide, as judged by the lack of an effect of GSH on the rate of decomposition of TCE oxide. Studies with the model enzymes aldolase and glucose-6-phosphate dehydrogenase, both known to have sensitive lysine groups, indicate that TCE oxide has effects similar to known acylating agents that form the same adducts; concentrations of TCE oxide (or the model acylating agents) in the low-millimolar range were needed for inhibition. The characterization of TCE-derived protein adducts can be used as a basis for consideration of the exposure and risk of TCE to humans. Human P450 2E1 was less likely to oxidize TCE to form TCE oxide and protein lysine adducts than rat P450 2B1, and the difference is rationalized in terms of the influence of the protein on chloride migration in an enzyme reaction intermediate.
 ...
PMID:Acylation of protein lysines by trichloroethylene oxide. 1081 48

An expressed sequence tag (EST) analysis approach was undertaken to identify major genes involved in cold acclimation of Rhododendron, a broad-leaf, woody evergreen species. Two cDNA libraries were constructed, one from winter-collected (cold-acclimated, CA; leaf freezing tolerance -53 degrees C) leaves, and the other from summer-collected (non-acclimated, NA; leaf freezing tolerance -7 degrees C) leaves of field-grown Rhododendron catawbiense plants. A total of 862 5'-end high-quality ESTs were generated by sequencing cDNA clones from the two libraries (423 from CA and 439 from NA library). Only about 6.3% of assembled unique transcripts were shared between the libraries, suggesting remarkable differences in gene expression between CA and NA leaves. Analysis of the relative frequency at which specific cDNAs were picked from each library indicated that four genes or gene families were highly abundant in the CA library including early light-induced proteins (ELIP), dehydrins/late embryogenesis abundant proteins (LEA), cytochrome P450, and beta-amylase. Similarly, seven genes or gene families were highly abundant in the NA library and included chlorophyll a/b-binding protein, NADH dehydrogenase subunit I, plastidic aldolase, and serine:glyoxylate aminotransferase, among others. Northern blot analyses for seven selected abundant genes confirmed their preferential expression in either CA or NA leaf tissues. Our results suggest that osmotic regulation, desiccation tolerance, photoinhibition tolerance, and photosynthesis adjustment are some of the key components of cold adaptation in Rhododendron.
 ...
PMID:Comparative analysis of expressed sequence tags from cold-acclimated and non-acclimated leaves of Rhododendron catawbiense Michx. 1593 92