Mitochondrial aldehyde dehydrogenase from higher plants

Aldehyde dehydrogenase has been purified to homogeneity from mitochondria of potato tubers and pea epicotyls. Although the enzyme had a high affinity for glycolaldehyde it also had a high affinity for a number of other aliphatic and arylaldehydes. It is proposed that the codification glycolaldehyde dehydrogenase (EC 1.2.1.22) should be abandoned in favour of mitochondrial aldehyde dehydrogenase (EC 1.2.1.3). The purified enzyme showed esterase activity and had properties similar to those reported for the mammalian mitochondrial aldehyde dehydrogenase. Although the natural substrate(s) for the enzyme is not known, the kinetic properties of the enzyme are consistent with it playing a role in the oxidation of acetaldehyde, glycolaldehyde and indoleacetaldehyde.     

The physiological role of the isoenzymes of lactate dehydrogenase in potatoes

Four of the five isoenzymes of lactate dehydrogenase present in potato tubers have been isolated and their kinetic properties examined. The pyruvate-reductase activity of isoenzyme-4 is greatly reduced at low pH, the affinity for both pyruvate and NADH is reduced and ATP has a stronger inhibitory effect. If the design properties of an enzyme dictate a high affinity for substrates, then the Km values for lactate, glyoxylate and NAD are consistent with an oxidative role for isoenzyme-4. The same considerations do not permit a conclusion about the physiological role of isoenzymes-1 to-3. However, an overview of the kinetic properties of these isoenzymes indicates that isoenzyme-1 is best adapted for the role of pyruvate reductase. Consideration of the relationships between kinetic constants and electrophoretic mobilities of the isoenzymes, leads us to predict that isoenzyme-5 is well adapted for a role in the oxidation of lactate or glyoxylate. The lactate dehydrogenase of potato leaves appears to consist prodominantly of an isoenzyme with the same mobility as isoenzyme-2 of the tubers and the two isoenzymes are probably identical. The kinetic properties of this isoenzyme are consistent with roles in either oxidation or reduction.Abbreviation Tris 2-amino-2-(hydroxymethyl)-1,3-propanediol     

Interleukin-4 as a potent inhibitor of bone resorption

A possible role of interleukin-4 (IL-4) in the regulation of bone turnover was assessed by employing a 45Ca prelabeled-fetal mouse long bone culture system. IL-4 inhibited the bone resorption stimulated by parathyroid hormone (PTH), PTH related protein (PTHrP), 1 alpha, 25, dihydroxy-vitamin D3 [1 alpha, 25 (OH)2 D3], interleukin-1 alpha and - 1 beta (IL-1 alpha, IL-1 beta) and prostaglandin E2 (PGE2). Anti-IL-4 on monoclonal antibody abolished the inhibitory effect of IL-4 on the bone resorption. These results suggest that IL-4 may play an important role on the inhibitory regulation of bone resorption.     

Phosphorylation-dependent subcellular redistribution of small myosin light chain kinase

BackgroundMyosin light chain kinase (MLCK) is a Ca²⁺-calmodulin-dependent enzyme dedicated to phosphorylate and activate myosin II to provide force for various motile processes. In smooth muscle cells and many other cells, small MLCK (S-MLCK) is a major isoform. S-MLCK is an actomyosin-binding protein firmly attached to contractile machinery in smooth muscle cells. Still, it can leave this location and contribute to other cellular processes. However, molecular mechanisms for switching the S-MLCK subcellular localization have not been described.MethodsSite-directed mutagenesis and in vitro protein phosphorylation were used to study functional roles of discrete in-vivo phosphorylated residues within the S-MLCK actin-binding domain. In vitro co-sedimentation analysis was applied to study the interaction of recombinant S-MLCK actin-binding fragment with filamentous actin. Subcellular distribution of phosphomimicking S-MLCK mutants was studied by fluorescent microscopy and differential cell extraction.ResultsPhosphorylation of S-MLCK actin-binding domain at Ser25 and/or Thr56 by proline-directed protein kinases or phosphomimicking these posttranslational modifications alters S-MLCK binding to actin filaments both in vitro and in cells, and induces S-MLCK subcellular translocation with no effect on the enzyme catalytic properties.ConclusionsPhosphorylation of the amino terminal actin-binding domain of S-MLCK renders differential subcellular targeting of the enzyme and may, thereby, contribute to a variety of context-dependent responses of S-MLCK to cellular and tissue stimuli.General significanceS-MLCK physiological function can potentially be modulated via phosphorylation of its actin recognition domain, a regulation distinct from the catalytic and calmodulin regulatory domains.     

Effects of stocking density during live transportation on haematological parameters of Siberian sturgeon (Acipenser baerii,Brandt, 1869)

In this study, we investigated the effects of different stocking densities water quality and blood parameters during the transportation of the Siberian sturgeon (Acipenser baerii). Experiments were carried out in high-density polyethylene tank with three different stocking densities (50, 100 and 150 kg/m³) for 20 h. Ammonium nitrogen (NH₄-N) and nitrite nitrogen (NO₂-N) were measured in the water samples. The erythrocyte, leucocyte, haematocrit (HCT), haemoglobin (Hb), cortisol, and sodium ion (Na⁺) were measured in blood samples. Ammonium nitrogen and nitrite nitrogen concentrations in the water have increased in parallel with the stocking density depending on the time. In the highest stocking density, the maximum levels of NH₄-N and NO₂-N at the 16^th h reached 2.64 mg/L and 4.74 mg/L, respectively. Erythrocyte, leucocyte, HCT, and Hb values did not differ significantly between the experimental groups (p > .05). The results showed that fish could be transported safely for 20 h in 15℃ water temperature at 50 kg/m³ stocking density; however, stocking density of 100 kg/m³ and over could threaten fish welfare and health as from 16^th h.     

Enantioselective Ethylation of Various Aldehydes Catalyzed by Readily Accessible Chiral Diols

Four chiral C₂‐symmetric diols were synthesized in a straightforward three‐step reaction and demonstrated excellent enantioselectivities and good overall yields. Their catalytic activities were examined via the addition of diethylzinc to various aldehydes. The enantioselective addition of diethylzinc to 2‐methoxybenzaldehyde gave the corresponding chiral secondary alcohol with high yields (up to 95%) and moderate to good enantiomeric excess (up to 88%). All synthesized ligands were evaluated in the addition of diethylzinc to various aldehydes in the presence of an additional metal such as Ti(IV) complexes. Chirality 28:593–598, 2016. © 2016 Wiley Periodicals, Inc.     

Splendours and miseries of the brain

In this speculative essay, I examine two evolutionary developments underlying the enormous success of the human brain: its capacity to acquire knowledge and its variability across individuals. A feature of an efficient knowledge-acquiring system is, I believe, its capacity to abstract and to formulate ideals. Both attributes carry with them a clash between experience of the particular and what the brain has developed from experience of the many. Both therefore can lead to much disappointment in our daily lives. This disappointment is heightened by the fact that both abstraction and ideals are subject to variability in time within an individual and between individuals. Variability, which is a cherished source for evolutionary selection, can also be an isolating and individualizing feature in society. Thus the very features of the human brain which underlie our enormous evolutionary success can also be a major source of our misery.