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21.
Enzymes involved in 3,5-diaminohexanoate degradation by Brevibacterium sp. 总被引:1,自引:1,他引:0
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Cell-free extracts of Brevibacterium sp. L5 grown on DL-erythro-3,5-diaminohexanoate were found to contain a 3-keto-5-aminohexanoate cleavage enzyme that converts 3-keto-5-aminohexanoate and acetyl-coenzyme A (CokA) to 3-aminobutyryl-CoA and acetoacetate and a deaminase that coverts L-3-aminobutyryl-CoA to crotonyl-CoA. The cleavage enzyme has been purified extensively, and some of its properties have been determined for comparison with the 3-keto-6-acetamido-hexanoate cleavage enzyme of Pseudomonas sp. B4. The deaminase has been partially purified and characterized. Both the cleavage enzyme and the deaminase are induced by growth on 3,5-diaminohexanoate. The presence of these and other accessory enzymes in Brevibacterium sp. extracts accounts for the results of earlier tracer experiments which showed that C-1 and C-2 of 3-keto-5-aminohexanoate are converted mainly to acetoacetate and acetate, whereas C-3 to C-6 are converted mainly to 3-hydroxybutyrate or its coenzyme A thiolester. The enzymes observed in extracts of Brevibacterium sp. can account for the conversion of 3,5-diaminohexanoate to acetyl-CoA. 相似文献
22.
BLood samples were collected from 89 Holstein cows on days 220 and 250 of gestation, within 24 hr prepartum and postpartum and on day 30 postpartum. Balanced diets which contained either chopped hay (29 cows), hay crop silage (HCS; 30 cows) or corn silage (CS; 30 cows) were fed from day 220 of gestation to day 30 postpartum. The purpose was to determine if variations in certain blood traits were indicative of peripartum and postpartum disorders. The blood traits evaluated were concentrations of plasma total protein, whole blood hemoglobin, packed cell volume, and white blood cells, and serum glutamic oxalacetic transaminase (SGOT), glucose, urea nitrogen, calcium, inorganic phosphorus, magnesium, potassium and sodium. No blood trait was useful to predict a disorder prior to its visual signs with one possible exception. Serum glucose and calcium were lower and SGOT and magnesium were higher peripartum which was prior to death of three cows from fat cow syndrome. 相似文献
23.
The effects of acetylcholine (Ach) on growth, the total peroxidase activity and the isoperoxidase spectrum of the roots ofLens culinaris were studied and compared with actual and earlier results obtained with an auxin (IAA) treatment. The general growth and
peroxidase activity patterns of Ach treated roots and IAA treated ones showed many important similarities. 相似文献
24.
Parab Ankita Rajendra Lynn Chew Bee Subramaniam Sreeramanan 《Molecular biology reports》2021,48(11):7223-7231
Molecular Biology Reports - Clonal propagation is one of the attributes of plant tissue culture. Therefore, analysis of genetic stability among the in vitro cultured plants is a crucial step. It... 相似文献
25.
26.
SH Chew 《Biotechnic & histochemistry》2013,88(5-6):177-183
The phagocytic activity of neuroglial cells in adult feline degenerating optic nerve was investigated by immunocytochemistry at both light and electron microscopy levels. Degeneration was initiated by unilateral eye enucleation and the segment distal to the transection showing true Wallerian degeneration was examined. Following enucleation, twelve adult domestic cats were examined over a period of seven to 215 days. All cases showed slow clearance of myelin debris and absence of proliferating monocytes throughout the post-enucleation period. All phagocytic cells present were neuroglial cells, and many of these cells expressed oligodendroglial antigens. These findings demonstrate the persistence of an active population of oligodendrocytes that might play an additional functional role during Wallerian degeneration of feline optic nerve. 相似文献
27.
Xiu L. Chen Nicklaus L. J. E. Wee Kum C. Hiong Jasmine L. Y. Ong You R. Chng Biyun Ching Wai P. Wong Shit F. Chew Yuen K. Ip 《PloS one》2013,8(12)
The swamp eel, Monopterus albus, can survive in high concentrations of ammonia (>75 mmol l−1) and accumulate ammonia to high concentrations in its brain (∼4.5 µmol g−1). Na+/K+-ATPase (Nka) is an essential transporter in brain cells, and since NH4
+ can substitute for K+ to activate Nka, we hypothesized that the brain of M. albus expressed multiple forms of Nka α-subunits, some of which might have high K+ specificity. Thus, this study aimed to clone and sequence the nka α-subunits from the brain of M. albus, and to determine the effects of ammonia exposure on their mRNA expression and overall protein abundance. The effectiveness of NH4
+ to activate brain Nka from M. albus and Mus musculus was also examined by comparing their Na+/K+-ATPase and Na+/NH4
+-ATPase activities over a range of K+/NH4
+ concentrations. The full length cDNA coding sequences of three nkaα (nkaα1, nkaα3a and nkaα3b) were identified in the brain of M. albus, but nkaα2 expression was undetectable. Exposure to 50 mmol l−1 NH4Cl for 1 day or 6 days resulted in significant decreases in the mRNA expression of nkaα1, nkaα3a and nkaα3b. The overall Nka protein abundance also decreased significantly after 6 days of ammonia exposure. For M. albus, brain Na+/NH4
+-ATPase activities were significantly lower than the Na+/K+-ATPase activities assayed at various NH4
+/K+ concentrations. Furthermore, the effectiveness of NH4
+ to activate Nka from the brain of M. albus was significantly lower than that from the brain of M. musculus, which is ammonia-sensitive. Hence, the (1) lack of nkaα2 expression, (2) high K+ specificity of K+ binding sites of Nkaα1, Nkaα3a and Nkaα3b, and (3) down-regulation of mRNA expression of all three nkaα isoforms and the overall Nka protein abundance in response to ammonia exposure might be some of the contributing factors to the high brain ammonia tolerance in M. albus. 相似文献
28.
Ip Yuen K. Hiong Kum C. Teng Joey H. Q. Boo Mel V. Choo Celine Y. L. Wong Wai P. Chew Shit F. 《Coral reefs (Online)》2020,39(2):451-465
Coral Reefs - Giant clams flourish in nutrient-poor waters of tropical Indo-Pacific because they live in symbiosis with extracellular dinoflagellates (zooxanthellae) and receive photosynthates from... 相似文献
29.
Whether pollen do reach the broncho-alveolar part of the respiratory tract to trigger a bronchospasm or not, has been studied for over a long period and many methods have been used. We assesed this question by the method of broncho-alveolar lavage and came to the conclusion that pollen do incidentally penetrate into the lower airways. It is probably not an event which happens very frequently and certainly not massively. 相似文献
30.
The East Kleinemonde Estuary, on the south-east coast of South Africa, typically opens for only short periods, usually <10 days. During a nine-month study in 2006, marine influence persisted for a near-continuous period of three months. This provided an opportunity to explore potential changes in the structure and pattern of the subtidal estuarine macrozoobenthic community. Salinity changes were minimal after mouth opening, decreasing by c. 4 and 8 in the lower and upper estuary, respectively. Salinity decrease was due to river dominance over tidal influence. Two biotic assemblages, structured by sediment characteristics, typified the community throughout the study: a sand-associated group near the mouth and a mud-associated group upstream. Amphipods were proportionally the most abundant group within each assemblage and on each sampling occasion. At the species level, high variability typified the community, with no trends or patterns observed. However, species richness declined from 27–30 to 23 after mouth opening. The number of species returned to former levels at the time of the final survey and just before final mouth closure. An analysis of the subtidal macrozoobenthos in the East Kleinemonde and other temporarily open/closed estuaries (TOCEs) of similar size in the bioregion indicated that communities were typically composed of relatively few, broadly tolerant euryhaline species with no species unique to TOCEs. 相似文献