Cis,cis-muconate lactonizing enzyme from Trichosporon cutaneum: evidence for a novel class of cycloisomerases in eucaryotes.

The absolute stereochemical courses of cis,cis-muconate lactonizing enzyme (MLE;EC 5.5.1.1) from Trichosporon cutaneum (TcMLE) and chloromuconate cycloisomerase (MLE II; EC 5.5.1.7) from Pseudomonas sp B13 have been determined from 1H NMR measurements. Both cycloisomerases convert cis,cis-muconate to (4S)-muconolactone by a syn lactonization, the absolute stereochemical outcome of which is identical to that observed with MLE from Pseudomonas putida. The regiochemical courses of cyclization of 3-halo-cis,cis-muconates by TcMLE and MLE II have been characterized and shown to differ in a halogen substituent dependent manner, suggesting at least a different active site architecture of the two MLEs. Moreover, the regiochemical preferences of MLE II and TcMLE parallel results previously observed for the nonenzymatic lactonization of the 3-halomuconates at pH 1-6 and in concentrated HCl, respectively, in which alternate mechanisms of cyclization were proposed [Pieken, W. A., & Kozarich, J. W. (1990) J. Org. Chem. 55, 3029-3035]. Complementary DNA clones encoding TcMLE have been isolated from phenol induced T. cutaneum cDNA using the polymerase chain reaction. The deduced amino acid sequence does not exhibit any similarity to that of MLE from P. putida. It does however, exhibit moderate sequence similarity (21% residue identity, 14 gaps) with 3-carboxy-cis,cis-muconate lactonizing enzyme (CMLE; EC 5.5.1.5) from Neurospora crassa, which catalyzes a regiochemically analogous and stereochemically identical lactonization reaction with 3-carboxymuconate. The limited data available suggest that the fungal CMLE and yeast MLE are representative of a unique class of eucaryotic cycloisomerases which have evolved convergently with the bacterial MLEs.

[Amyloidosis lesions of the digestive organs in patients with tuberculosis and chronic nonspecific lung diseases]. / Porazhenie amiloidozom organov pishchevareniia u bol'nykh tuberkulezom i khronicheskimi nespetsificheskimi zabolevaniiami legkikh.

Histological postmortem examination of 30 persons who had died of pulmonary tuberculosis complicated by renal amyloidosis revealed amyloid affections in the rectum, stomach and liver of 76.3, 60 and 56.7 per cent of the dead, respectively. Histological examination of biopsy specimens of the gastric and duodenal mucosa from 20 patients with pulmonary tuberculosis revealed amyloid affections in 17 of them (85 per cent). An analogous examination of 18 patients with chronic nonspecific diseases of the lungs revealed amyloidosis of the organs in 10 persons (55.6 per cent). Efficiency of using proteinase inhibitors such as amben, epsilon-aminocapronic acid and contrical in the prevention and treatment of secondary amyloidosis of the digestive organs was studied experimentally.

Oxygen deficiency hazards associated with liquefied gas systems: derivation of a program of controls.

The use of liquefied gases in industry and research has become commonplace. Release into the atmosphere of these gases will result in a displacement of air and a reduction in the oxygen concentration. Exposure to reduced levels of oxygen may cause reduced abilities, unconsciousness or death. This paper describes the derivation of a novel program of controls for oxygen deficiency hazards. The key to this approach is a quantitative assessment of risk for each planned operation and the application of control measures to reduce that risk to an acceptable level. Five risk levels evolve which are based on the probability of fatality. Controls such as training, oxygen monitoring equipment, self-rescue respirators and medical surveillance are required when the probability of fatality exceeds 10(-7) per hour. The quantitative nature of this program ensures an appropriate level of control without undue burden or expense.