Stereospecificity of hydrogen transfer of aldehyde reductase

Summary Aldehyde reductase from human liver catalyzes the hydrogen transfer from the pro-4R position on the dihydronicotinamide ring of the coenzyme to there face of the carbonyl carbon atom of the substrate.     

Stereospecificity of hydrogen transfer of aldehyde reductase.

Aldehyde reductase from human liver catalyzes the hydrogen transfer from the pro-4R position on the dihydronicotinamide ring of the coenzyme to the re face of the carbonyl carbon atom of the substrate.     

Stereospecificity of the prostaglandin 15-dehydrogenase from swine lung

Zusammenfassung Die stereochemischen Voraussetzungen der Prostaglandin-15-Dehydrogenase aus Schweinelunge werden im Hinblick auf die pharmakologische Aktivität anhand einer Reihe synthetischer Prostaglandin E₁-Präparate abgeklärt.

---

---

This work was supported by grants from the U.S. National Institutes of Health to Harvard University and by O.N.R. and N.I.H. grants to the Worcester Foundation for Experimental Biology.     

Microbial degradation of bitumen

Summary A blown bitumen Mexphalte R 90/40 with a high content of saturated hydrocarbons was degraded by several microorganisms to the same extent. In batch cultures ofSaccharomycopsis lipolytica, maximal biodegradation was estimated to be about 9% w/w, 3.2·10^–3 g/cm² and 3.1·10^–3 cm of degraded bitumen. The Mexphalte R 90/40 degradation rate was closely coupled to biofilm formation. The microbial activity concerned predominantly the oxidation of saturated hydrocarbons. A direct distillation bitumen 80/100 with a low content of saturated hydrocarbons and a high content of aromatic hydrocarbons and resins was more resistant to biodegradation.     

Genetic analysis of ubiquitin-dependent protein degradation

Selective degradation of cellular proteins serves to eliminate abnormal proteins and to mediate the turnover of certain short-lived proteins, many of which have regulatory functions. In eukaryotes a major pathway for selective protein degradation is ATP-dependent and is mediated by the ubiquitin system. This pathway involves substrate recognition by components of a ubiquitin-protein ligase system, covalent attachment of ubiquitin moieties to proteolytic substrates, and subsequent degradation of these conjugates by a multicatalytic protease complex. Recent genetic evidence suggests that the remarkable selectivity of this process is largely controlled at the level of substrate recognition by the ubiquitin ligase system. InSaccharomyces cerevisiae, ubiquitin-conjugating enzymes UBC1, UBC4 and UBC5 have been identified as key components of this highly conserved degradation pathway. Genetic analysis indicates that ubiquitin-dependent proteolysis is essential for cell viability and that UBC4 and UBC5 enzymes are essential components of the eukaryotic stress response.     

Protein degradation in human T-lymphocytes

Summary Protein from resting or phytohemagglutinin-stimulated human peripheral blood T-lymphocytes, pulse-labeled in vitro for 1 h with³H-leucine, had a half-life of 30 h.     

Tryptophan degradation in autoimmune diseases

Recent evidence points to tryptophan (Trp) degradation as a potent immunosuppressive mechanism involved in the maintenance of immunological tolerance. Both Trp depletion and downstream Trp catabolites (TCs) appear to synergistically confer protection against excessive inflammation. In this review, we give an overview of the immunosuppressive properties of Trp degradation with special focus on TCs. Constitutive and inducible Trp degradation in different cell types and tissues of human and murine origin is summarized. We address the influence of Trp degradation on different aspects of autoimmune disorders such as multiple sclerosis. Possible therapeutic approaches for autoimmune disorders targeting Trp degradation are presented, and key issues relevant for the development of such therapeutic strategies are discussed.     

Regulated protein degradation in mitochondria

Various adenosine triphosphate (ATP)-dependent proteases were identified within mitochondria which mediate selective mitochondrial protein degradation and fulfill crucial functions in mitochondrial biogenesis. The matrix-localized PIM1 protease, a homologue of theEscherichia coli Lon protease, is required for respiration and maintenance of mitochondrial genome integrity. Degradation of non-native polypeptides by PIM1 protease depends on the chaperone activity of the mitochondrial Hsp70 system, posing intriguing questions about the relation between the proteolytic system and the folding machinery in mitochondria. The mitochondrial inner membrane harbors two ATP-dependent metallopeptidases, them- and thei-AAA protease, which expose their catalytic sites to opposite membrane surfaces and cooperate in the degradation of inner membrane proteins. In addition to its proteolytic activity, them-AAA protease has chaperone-like activity during the assembly of respiratory and ATP-synthase complexes. It constitutes a quality control system in the inner membrane for membrane-embedded protein complexes.     

Retarded enzymatic degradation of heterologous eledoisin sequences

Zusammenfassung Analoge des Eledoisin-Oktapeptides 4–11, die Hydrazid-Komponenten enthalten, sind durch Aminopeptidasen nur bis zur Heterobindung abbaubar. Sie werden wesentlich langsamer als die native Sequenz bzw. nicht durch Organhomogenate inaktiviert, wenn die Substitution im N-terminalen Bereich erfolgt. Mögliche sterische Veränderungen des Peptids durch eingebaute Fremdbausteine sind diskutiert.     

Enzymatic degradation of human lipoproteins by mycoplasmas

Zusammenfassung Die lipolytische Enzymaktivität saprophytärer und tierpathogener Mykoplasmenstämme wurde immunelektrophoretisch untersucht, wobei als Substrat menschliches Serum diente. Dabei wurde bei einigen Stämmen die Fähigkeit zum Abbau von ₁-Lipoprotein und von-Lipoprotein gefunden.

---

---

We thank Prof. H.Brandis for his interest in this work.