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1.
Isolation,Purification, and Characterization of Acetolactate Synthase from a Lactococcus lactis Culture 总被引:1,自引:0,他引:1
Kisrieva Yu. S. Serebrennikov V. M. Eneiskaya E. V. Zagustina N. A. Bezborodov A. M. 《Applied Biochemistry and Microbiology》2001,37(2):201-205
Acetolactate synthase catalyzing the synthesis of -acetolactate was isolated from lactic acid bacteria Lactococcus lactissubsp. lactisbiovar. diacetylactis4 and purified. Acetolactate synthase was shown to be an allosteric enzyme with low affinity for the substrate: the K
Mfor pyruvate was 70 mM. The curve relating the dependence of enzyme activity to pyruvate concentration had a sigmoid shape. The enzyme activity persisted for 24 h in the presence of stabilizers, pyruvate, and thiamine pyrophosphate. Acetolactate synthase had pH optimums of 5.8 and 6.5–7.0 in acetate and phosphate buffers, respectively. The temperature optimum for this enzyme was 38–40°C at pH 6.5. The molecular weight of acetolactate synthase was 150 kDa. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate showed that the enzyme consisted of three identical subunits with a molecular weight of 55 kDa. 相似文献
2.
Pedro LC Pinheiro João CR Cardoso Ana S Gomes Juan Fuentes Deborah M Power Adelino VM Canário 《BMC evolutionary biology》2010,10(1):373
Background
Parathyroid hormone (PTH) and PTH-related peptide (PTHrP) belong to a family of endocrine factors that share a highly conserved N-terminal region (amino acids 1-34) and play key roles in calcium homeostasis, bone formation and skeletal development. Recently, PTH-like peptide (PTH-L) was identified in teleost fish raising questions about the evolution of these proteins. Although PTH and PTHrP have been intensively studied in mammals their function in other vertebrates is poorly documented. Amphibians and birds occupy unique phylogenetic positions, the former at the transition of aquatic to terrestrial life and the latter at the transition to homeothermy. Moreover, both organisms have characteristics indicative of a complex system in calcium regulation. This study investigated PTH family evolution in vertebrates with special emphasis on Xenopus and chicken. 相似文献3.
4.
5.
Background
Although direct infiltration of papillary carcinoma of thyroid to larynx, trachea and esophagus is well recognized, lymphatic and vascular metastases to larynx and hypopharynx have rarely been reported. 相似文献6.
7.
Cyanobacterium Anacystis nidulans R2, Synechocystis sp. PCC 6803 (wild-type strain and mutants Delta2 and Delta3 lacking PSII and PSI, respectively), and Synechocystis sp. BO 9201 synthesize the pigment--protein complex CP36 (CPIV-4, CP43') under iron deficiency in the medium. Accumulation of CP36 is accompanied by structural reorganizations in the photosynthetic membranes. Integrating mean times of excitation relaxation (quenching) are 2.2 nsec (CP36), 1 nsec (PSI), and 420 psec (PSII in Fm state). The energy migration between CP36 and the photosystems can be described by a model of a one-layer ring of CP36 around core-complexes. The excitation from CP36 to PSI is transferred within <10 psec. The energy transfer from CP36 to PSII occurs during 170 psec. Cells with low content of CP36 probably contain only a latent fraction of unbound to phycobilisomes PSII which is the analog of PSIIbeta of higher plants. In PSI there are four binding sites for CP36 monomers per RC. PSII can bind up to 32 molecules of CP36 per RC. Cells with a large amount of CP36 contain monomer form of PSII core-complex which can bind eight tetramers of CP36 (8 binding sites). In conditions of iron deficiency only one monomer of a dimer PSII core-complex is destroyed and released chlorophyll is accumulated in CP36. Accumulation of CP36 in A. nidulans cells can be accompanied by membrane stacking which is similar to the stacking in chlorophyll b-containing organisms. The stacking can occur in the region of localization of PSII latent fraction bound to CP36. The membrane stacking shields PSII stromal surfaces from the aqueous phase for activation of electron transfer on the acceptor side of PSII. 相似文献
8.
H?Bukulmez AL?Matthews CM?Sullivan C?Chen MJ?Kraay RC?Elston RW?Moskowitz VM?Goldberg ML?WarmanEmail author 《Arthritis research & therapy》2005,8(1):R25
In order to determine whether there is a genetic component to hip or knee joint failure due to idiopathic osteoarthritis (OA),
we invited patients (probands) undergoing hip or knee arthroplasty for management of idiopathic OA to provide detailed family
histories regarding the prevalence of idiopathic OA requiring joint replacement in their siblings. We also invited their spouses
to provide detailed family histories about their siblings to serve as a control group. In the probands, we confirmed the diagnosis
of idiopathic OA using American College of Rheumatology criteria. The cohorts included the siblings of 635 probands undergoing
total hip replacement, the siblings of 486 probands undergoing total knee replacement, and the siblings of 787 spouses. We
compared the prevalence of arthroplasty for idiopathic OA among the siblings of the probands with that among the siblings
of the spouses, and we used logistic regression to identify independent risk factors for hip and knee arthroplasty in the
siblings. Familial aggregation for hip arthroplasty, but not for knee arthroplasty, was observed after controlling for age
and sex, suggesting a genetic contribution to end-stage hip OA but not to end-stage knee OA. We conclude that attempts to
identify genes that predispose to idiopathic OA resulting in joint failure are more likely to be successful in patients with
hip OA than in those with knee OA. 相似文献
9.
V. M. Serebrennikov L. N. Kotova A. V. Glazunov 《Applied Biochemistry and Microbiology》2014,50(7):689-700
We investigated the effects of the oxygen supply rate on the activity of pyruvate metabolic pathways and their end products, the lactatedehydrogenase (LDH), pyruvateformiatelyase (PFL), pyruvatedehydrogenase (PDH) and acetolactatesynthase (ALS) pathways, in the Lactococcus lactis ssp. lactis bv. diacetylactis strain B2103/74. We found that this culture, apart from inactivated α-acetyldecarboxylase, also possesses a unique natural capacity to overexpress α-acetolactate (AL) up to 25–28 mM. Our search for similar properties among the diacetilicus bv. strains showed that this ability is quite rare. We identified a single additional strain, 7590 from the National Russian Collection of Industrial Microorganisms (NRCIM-7590), which displayed a similar capacity. However, unlike B2103/74, NRCIM-7590 has an active α-acetolactate decarboxylase and therefore can only produce acetoin. AL overexpression took place under conditions of intense aeration (K L a ≥ 90–120 h?1), and the composition of the medium played a decisive role in AL productivity. We found that AL overproduction is determined by a diversion of a portion of pyruvate flow from the LDH to the PDH and ALS pathways. We further found that all additional pyruvate, supplied from LDH, is utilized exclusively by the ALS pathway because of the restricted capacity of the PDH pathway. This shift in pyruvate metabolism in the B2103/74 strain, from LDH to PDH and ALS pathways, is associated with the initiation of an oxidation reaction that reduces oxygen to H2O and sequesters NADH from the LDH pathway in the process. A specific manifestation of this reaction in B2103/74 and NRCIM-7590 cultures, which results in a profound shift of the pyruvate metabolism towards the production of α-acetolactate, is due to the function of a potent oxidative system that shifts 75–80% of NADH flow from LDH to the oxidative pathway, resulting in the regeneration of NAD+. The nature of this oxidative system is not known. Based on our studies, we propose that the structure of the newly discovered oxidative system is similar to a simple transmembrane electron transport chain. 相似文献
10.
Raffael AC Oliveira Ricardo VM Almeida Márcia DA Dantas Felipe N Castro Jo?o Paulo MS Lima Daniel CF Lanza 《BMC bioinformatics》2014,15(1)